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CA-125 a glycoprotein found in the blood serum of patients with ovarian or other glandular cell carcinomas. Increasing levels of the antigen mean increasing tumour growths which may indicate poor prognosis. Also known as cancer cell surface antigen 125.

cachexia a condition of extreme debility typical of the late stages of chronic disease, symptoms include weight loss and general bodily deterioration.

cadaver a corpse. In a medical context it implies a dead body which is dissected in a medical school, or in a mortuary at a postmortem examination.

caecum the blind, pouch-like commencement of the colon in the right iliac fossa. To it is attached the vermiform appendix; it is separated from the ileum by the ileocaecal valve.

caesium-137 (¹³⁷Cs) a radioactive substance which, when sealed in needles or tubes, can be used for interstitial and surface applications. It can also be employed as a source for treatment by Selectron. Historically has been used for external beam therapy.

caesium iodide crystal a crystal which used to be used in the detector of a CT scanner to detect any radiation passing through the patient. Now obsolete. See also ceramic detectors.

caisson disease results from sudden reduction in atmospheric pressure, as experienced by divers on return to surface, aircrew ascending to great heights. Caused by bubbles of nitrogen which are released from solution in the blood; symptoms vary according to the site of these. The condition is largely preventable by proper and gradual decompression technique. See also decompression illness.

calamine zinc carbonate with ferric oxide. Used in lotions and creams for the relief of itching; however, it is not generally effective.

calcaneus (calcaneum, os calcis) the heel bone.

calcareous chalky. Relating to lime or calcium.

calcification the hardening of an organic substance by a deposit of calcium salts within it. May be physiological, as in bone, or pathological, as in arteries.

calcitonin (thyrocalcitonin) hormone secreted by the thyroid gland. It has a fine-tuning role in calcium homeostasis. It opposes the action of parathyroid hormone and reduces levels of calcium and phosphate in the serum by its action on the kidneys and bone. It inhibits calcium reabsorption from bone and stimulates the excretion of calcium and phosphate in the urine. Calcitonin is released when the serum calcium level rises. Synthetic calcitonin is used in the management of metastatic bone cancer, Paget’s disease and osteoporosis.

calcitriol (1,25-dehydroxycholecalciferol) the active form of vitamin D concerned with calcium homeostasis.

calcium (Ca) a metallic element. Needed by the body for neuromuscular conduction and blood coagulation and as an important component of the skeleton and teeth. An essential nutrient.

calcium carbonate a calcium salt used in many antacid medicines.

calcium gluconate a calcium salt used to treat calcium deficiencies and disorders such as rickets.

calcium tungstate the main phosphor used in conventional intensifying screens now superseded by rare earth phosphors.

calculus a stone, small mineral deposits. Examples include gallstones and renal calculi. dental calculus a hard calcified deposit that forms on the surface of the teeth, also known as tartar.

Caldwell–Luc operation (radical antrostomy) a radical operation previously used for sinusitis.

calibrated stepwedge a piece of equipment which is made up of different thickness of aluminium with a layer of copper on the base, wedges are calibrated so that when radiographed each step produces an exact increase or decrease in density on the film. See also stepwedge.

caliper a two-pronged instrument for measuring the diameter of a round body, used chiefly in pelvimetry. A two-pronged instrument with sharp points which are inserted into the lower end of a fractured long bone, a weight is attached to the other end of the caliper, which maintains a steady pull on the distal end of the bone. Thomas’ walking caliper is similar to the Thomas’ splint, but the W-shaped junction at the lower end is replaced by two small iron rods which slot into holes made in the heel of the boot, the ring should fit the groin perfectly, and all weight is then borne by the ischial tuberosity.

callus the partly calcified tissue which forms about the ends of a broken bone and ultimately accomplishes repair of the fracture, when this is complete the bony thickening is known as permanent callus. corn (callosity, keratoma, mechanically induced hyperkeratosis) a yellowish plaque of hard skin caused by pressure or friction, the stratum corneum becomes hypertrophied, most commonly seen on the feet and palms of the hands. A painful, cone-shaped overgrowth and hardening of the epidermis, with the point of the cone in the deeper layers. Corns on the sole of the foot and over joints are often described as hard corns, and those occurring between the toes are described as soft corns.

calor heat: one of the five classic local signs and symptoms of inflammation, the others are dolor, loss of function, rubor and tumor.

calorie a unit of heat. In practice the calorie is too small a unit to be useful and the kilocalorie (kcal) is the preferred unit in studies in metabolism. A kcal is the amount of heat required to raise the temperature of 1kg of water by 1öC. In medicine, science and technology generally, the calorie has been replaced by the joule (derived SI unit) as a unit of energy, work and heat. For approximate conversion: 4.2kJ=1kcal.

calorific describes any phenomena that relate to heat production.

calorimetry the precise method of measuring the absorbed dose of radiation in a body by calculating the temperature rise when the body is irradiated.

Campylobacter a genus of Gram-negative motile bacteria. Campylobacter jejuni is a common cause of bacterial food poisoning. It causes abdominal pain and bloodstained diarrhoea that may last for 10–14 days. The microorganism is associated with raw meat and poultry, the fur of infected pet animals and unpasteurized milk. No reported person-to-person spread.

canal a bony tunnel.

canaliculus a minute capillary passage. Any small canal, such as the passage leading from the edge of the eyelid to the lacrimal sac or one of the numerous small canals leading from the Haversian canals and terminating in the lacunae of bone.

canal of Schlemm a canal in the inner part of the sclera, close to its junction with the cornea, which it encircles. It drains excess aqueous humour to maintain normal intraocular pressure. Impaired drainage results in raised intraocular pressure.

cancellous resembling latticework; light and spongy; like a honeycomb. Describes a type of bone tissue.

cancer a general term which covers any malignant growth in any part of the body. The growth is purposeless, parasitic, and flourishes at the expense of the human host. Characteristics are the tendency to cause local destruction, to invade adjacent tissues and to spread by metastasis. Frequently recurs after removal. carcinoma refers to malignant tumours of epithelial tissue, sarcoma to malignant tumours of connective tissue.

cancerophobia obsessive fear of cancer.

candela (cd) one of the seven base units of the International System of Units (SI). Measures luminous intensity.

candida (Monilia) a type of fungi which is widespread in nature.

candidiasis (candidosis, moniliasis, thrush) infection caused by a species of Candida, usually Candida albicans. Infection may involve the mouth, gastrointestinal tract, skin, nails, respiratory tract or genitourinary tract (vulvovaginitis, balanitis), especially in individuals who are debilitated, for example, by cancer or diabetes mellitus, or immunosuppressed and after long-term or extensive treatment with antibiotics, which upsets the microbial flora, and other drugs, for example, corticosteroids. Oral infection can be caused by poor oral hygiene, including carious teeth and ill-fitting dentures.

canine of or resembling a dog.

canine tooth pointed tooth with a single cusp (cuspid) and root, placed third from the midline in both primary and secondary dentitions. A lay term for the upper permanent canine is ‘eye tooth’. There are four in all.

cannula a hollow tube, usually plastic, for the introduction or withdrawal of fluid from the body. In some types the lumen is fitted with a sharp-pointed trocar to facilitate insertion, which is withdrawn when the cannula is in situ.

cannulation insertion of a cannula, such as into a vein to facilitate the administration of intravenous fluids.

cans the container for the sodium iodide crystals of scintillation counters to prevent the absorption of moisture by the crystal which would make it cloudy.

canthus the angle formed by the junction of the eyelids. The inner one is known as the nasal canthus and the outer as the outer (temporal) canthus.

capacitance is the amount of charge a body can hold per unit potential difference. In a sphere the capacitance is the ratio of the total charge on the body to its potential. If there are two surfaces the capacitance is the ratio of the total charge of one sign on the body to the potential difference between the surfaces.

capacitor an electrical component consisting of two plates separated by a dielectric, when it receives a potential difference across the plates a charge is stored.

capelline bandage (divergent spica) a bandage applied in a circular fashion to the head or an amputated limb.

capillary literally, hair-like; any tiny thin-walled vessel forming part of a network which facilitates rapid exchange of substances between the contained fluid and the surrounding tissues. bile capillary begins in a space in the liver and joins others, eventually forming a bile duct. blood capillary unites an arteriole and a venule. capillary fragility an expression of the ease with which blood capillaries may rupture. lymph capillary begins in the tissue spaces throughout the body and joins others, eventually forming a lymphatic vessel.

capillary blockade the injection of large radioactive particles (20–50 μm) that are unable to pass through capillaries and therefore block the first capillary bed they reach. Used in radionuclide imaging to see the vascular bed of the lungs.

capital budget financial allocation for the purchase of items, such as equipment, that will last longer than 12 months, or items that cost more than an agreed level. See also revenue budget.

capitate forms one of the carpal bones of the wrist.

capitation funding method of allocating money and other resources based on the number of people living in a geographical area. See also weighted capitation.

capsule the ligaments which surround a joint. A gelatinous or rice paper container for a drug. The outer membranous covering of certain organs, such as the kidney, liver.

capsulectomy the surgical excision of a capsule. Refers to a joint or lens; less often to the kidney.

capsulitis inflammation of a capsule. Sometimes used as a synonym for frozen shoulder.

carbaminohaemoglobin a compound formed between carbon dioxide and haemoglobin. Some carbon dioxide in the blood is carried in this form.

carbohydrate an organic compound containing carbon, hydrogen and oxygen. Formed in nature by photosynthesis in plants. Carbohydrates are the major source of energy in most diets, on average 1g of carbohydrate is metabolized to produce 16kJ heat. They include starches, sugars and non-starch polysaccharides (NSP), and are classified in three groups – monosaccharides, disaccharides and polysaccharides.

carbon a non-metallic element found in all organic molecules and living matter. Carbon can bond with four other atoms and is able to form a huge number of complex molecules.

carbon dioxide a gas; a waste product of many forms of combustion and metabolism, excreted via the lungs. Builds up in respiratory insufficiency or failure and carbon dioxide tension in arterial blood (PaCO₂) rises above normal levels.

carbon monoxide a poisonous gas that combines with haemoglobin to form a stable compound. This blocks the normal reversible oxygen-carrying function and leads to hypoxia. The onset of hypoxia may be insidious but it is associated with confusion, headache, increasing respiratory rate, flushed appearance, changes in conscious level, seizures and cardiac arrhythmias.

carbon tetrachloride colourless volatile liquid used in dry cleaning and some types of antifreeze. Exposure may result in toxicity and liver damage.

carbonic anhydrase an enzyme that assists the transfer of carbon dioxide from tissues to blood and to alveolar air by reversibly catalysing the decomposition of carbonic acid into carbon dioxide and water.

carbonic anhydrase inhibitors drugs that reduce the production of aqueous humour, thereby reducing intraocular pressure. They also have diuretic effects.

carboxyhaemoglobin a stable compound formed by the union of carbon monoxide and haemoglobin; the red blood cells then lose their respiratory function.

carboxyhaemoglobinaemia carboxyhaemoglobin in the blood.

carboxyhaemoglobinuria carboxyhaemoglobin in the urine.

carbuncle an acute inflammation (usually caused by Staphylococcus). There is a collection of boils causing necrosis in the skin and subcutaneous tissue.

carcinoembryonic antigen (CEA) increased amounts in the serum of adults can be a tumour marker for colorectal cancers and for non-malignant conditions, such as liver cirrhosis caused by alcohol misuse.

carcinogen agent, substance or environment causing cancer.

carcinogenesis the production of cancer.

carcinoid syndrome cluster of symptoms including flushing, palpitation, diarrhoea and bronchospasm from histological (usually low grade) malignancy; often originates in the appendix.

carcinoma a malignant tumour of epithelial tissue (for example, mucous membrane) and derivatives such as glands.

carcinoma in situ condition with cells closely resembling cancer cells. A very early cancer. Well described in uterus and prostate. Previously called preinvasive carcinoma.

carcinomatosis widespread malignancy affecting many organs.

cardia the oesophageal opening into the stomach.

cardiac associated with the heart, associated with the cardia of the stomach.

cardiac arrest complete cessation of effective output (of blood) from heart activity. Failure of the heart action to maintain an adequate circulation. The clinical picture of cessation of circulation in a patient who was not expected to die at the time.

cardiac bed one which can be manipulated so that the patient is supported in a sitting position.

cardiac bypass operation; the bypassing of atheromatous vessels supplying heart muscle (myocardium).

cardiac catheterization a long plastic catheter or tubing is inserted into an artery or vein and moved under X-ray guidance until it reaches the heart. A catheter inserted into the brachial or femoral artery gives access to the left side of the heart and those inserted into the brachial or femoral vein can be guided into the right atrium, ventricle and the pulmonary artery. Cardiac catheterization can be used for: (a) recording pressures and cardiac output; (b) the introduction of radiopaque contrast agent for angiography; (c) treatments, such as angioplasty and stent insertion. See also angioplasty.

cardiac cycle the series of movements through which the heart passes in performing one heart beat, which corresponds to one pulse beat and takes about one second. See also diastole, systole.

cardiac enzymes released from damaged myocardial cells. Abnormal levels found in the blood are suggestive of a diagnosis of myocardial infarction. Used to confirm or refute the diagnosis of myocardial infarction. The enzymes usually measured are troponins and creatine kinase (CK) but aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) may also be measured.

cardiac massage performed during cardiac arrest. With the person lying on his or her back on a firm surface, the lower part of the sternum (breastbone) is depressed to compress the heart and force blood into the circulation. See also cardiopulmonary resuscitation (CPR).

cardiac monitor equipment used to visually record the heart cycle and therefore monitor the activity of the heart.

cardiac oedema gravitational oedema. Such patients secrete excessive aldosterone which increases excretion of potassium and conserves sodium and chloride. Anti-aldosterone (aldosterone antagonists) drugs are useful, for example, spironolactone. See also oedema.

cardiac output (CO) the volume of blood ejected by the heart per minute, typically 4–5L/min at rest. It can be expressed as the cardiac index (CI), cardiac output divided by body surface area.

cardiac pacemaker an electrical device for maintaining myocardial contraction by stimulating the heart muscle. A pacemaker may be permanent or temporary. They are programmed in a variety of modes. Nowadays pacemakers can be programmed to alter their rate in response to physical activity.

cardiac tamponade excessive fluid surrounding the heart, usually blood when the cause is traumatic, causes compression of the heart especially the right ventricle leading to impaired cardiac function. Can occur in surgery and penetrating wounds or cardiac rupture.

cardialgia literally, pain in the heart. Often used to mean heartburn (pyrosis).

cardiogenic of cardiac origin.

cardiogenic shock shock caused when the action of the heart is impaired, for example, in heart failure, cardiac injury, disease of the heart muscles.

cardiograph an instrument for recording graphically the force and form of the heart beat.

cardiologist a medically qualified person who specializes in diagnosing and treating diseases of the heart.

cardiology study of the structure, function and diseases of the heart.

cardiomegaly enlargement of the heart.

cardiomyopathy a disease of the myocardium associated with cardiac dysfunction. It is classified as dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy or restrictive cardiomyopathy. Management includes treatment of the cause (if possible), treatment of heart failure and sometimes heart transplantation.

cardiophone a microphone strapped to a patient which allows audible and visual signal of heart sounds. By channelling pulses through an electrocardiograph, a graphic record can be made. Can be used for the fetus.

cardioplegia the use of an electrolyte solution to induce electromechanical cardiac arrest. cold cardioplegia combined with hypothermia to reduce the oxygen consumption of the myocardium during open heart surgery.

cardiopulmonary associated with the heart and lungs.

cardiopulmonary bypass used in open heart surgery. The heart and lungs are excluded from the circulation and replaced by a pump oxygenator.

cardiopulmonary resuscitation (CPR) the techniques used to maintain circulation and respiration following cardiopulmonary arrest. It involves (a) the maintenance of a clear airway, (b) artificial respiration using mouth-to-mouth or mouth-to-nose respiration, or with a bag and face mask, or by an endotracheal tube, and (c) maintenance of the circulation by external cardiac massage. See also resuscitation.

cardiorenal associated with the heart and kidney.

cardiorespiratory associated with the heart and the respiratory system.

cardiorrhaphy stitching of the heart wall: usually reserved for traumatic surgery.

cardiothoracic associated with the heart and thoracic cavity. A specialized branch of surgery.

cardiotocograph the instrument used in cardiotocography.

cardiotocography (CTG) a procedure whereby the fetal heart rate is measured either by an external microphone or by the application of an electrode to the fetal scalp, recording the fetal ECG and from it the fetal heart rate. An external transducer placed on the mother’s abdomen measures the uterine contractions.

cardiotomy syndrome pyrexia, pericarditis and pleural effusion following heart surgery. It may develop weeks or months after the operation and is thought to be an autoimmune reaction.

cardiotoxic describes any agent that has an injurious effect on the heart.

cardiovascular associated with the heart and blood vessels.

cardiovascular endurance the ability to sustain exercise without undue fatigue, cardiac distress or respiratory distress.

cardioversion use of electrical countershock for restoring the heart rhythm to normal.

carditis inflammation of the heart. A word seldom used without the appropriate prefix, for example, endo-, myo-, peri-.

caries inflammatory decay of bone, usually associated with pus formation. In dentistry tooth decay. See also dental caries.

carina a keel-like structure exemplified by the keel-shaped cartilage at the bifurcation of the trachea into two bronchi.

cariogenic causing caries, by convention referring to dental caries.

carneous mole a fleshy mass in the uterus comprising blood clot and a dead fetus or parts of a dead fetus that have not been expelled with miscarriage.

carotid the principal artery on each side of the neck. At the bifurcation of the common carotid into the internal and external carotids there are: (a) the carotid bodies a collection of chemoreceptors which, being sensitive to chemical changes in the blood, protect the body against lack of O₂; (b) the carotid sinus a collection of baroreceptors; increased pressure causes slowing of the heart beat and lowering of blood pressure.

carotid angiography the demonstration of the brain circulation by direct injection of a contrast agent into the carotid artery or via a catheter in the femoral vein which is passed to the carotid artery.

carpal associated with the wrist.

carpal bones the eight bones that lie between the distal end for the radius and ulna and the metacarpals.

carpal tunnel syndrome nocturnal pain, numbness, weakness of the thumb and tingling in the area of distribution of the median nerve in the hand. Due to compression as the nerve passes under the fascial band. Most common in middle-aged women.

carpometacarpal associated with the carpal and metacarpal bones.

carpopedal associated with the hands and feet.

carpopedal spasm painful spasm of hands and feet in tetany. See also hypocalcaemia.

carpus the bones of the wrist.

carrier a person who harbours microorganisms of an infectious disease without showing symptoms and who can transmit infection to others. A person who carries a recessive gene at a specific chromosome location (locus) and therefore passes on a hereditary abnormality.

cartesian co-ordinate the point on a graph where the value of x meets the value of y.

cartilage a dense connective tissue capable of withstanding pressure. There are several types according to the function it has to fulfil. There is relatively more cartilage in a child’s skeleton but much of it has been converted into bone by adulthood.

cartilaginous joints (amphiarthroses) joints with either no movement or minimal movement and joined by a layer of cartilage.

caruncle a red fleshy projection. Hymenal caruncles surround the entrance to the vagina after rupture of the hymen. The lacrimal caruncle is the fleshy prominence at the inner angle of the eye.

case–control study a retrospective research study that compares outcomes for a group with a particular condition with those of a control group who do not have the condition.

case study research that studies data from one case, or a small group of cases.

caseation the formation of a soft, cheese-like mass, as occurs in tuberculosis.

caseous degeneration cheese-like tissue resulting from atrophy in a tuberculoma or gumma.

Casoni test intradermal injection of fresh, sterile hydatid fluid. A white papule indicates a hydatid cyst.

cassette a piece of equipment to hold either an imaging plate or radiographic film. It may also contain intensifying screens and a grid.

cast material or exudate that has been moulded to the form of the cavity or tube in which it has collected. A rigid casing often made with plaster of Paris and applied to immobilize a part of the body.

castration surgical removal of the testes in the male, or of the ovaries in the female. Castration can be part of the treatment for a hormone-dependent cancer.

CAT computed axial tomography.

catabolism (katabolism) the series of chemical reactions in the living body whereby complex substances are broken down into simpler ones accompanied by the release of energy. This energy is needed for converting simple compounds into complex compounds in the body (anabolism), and the other activities of the body.

catalyst any substance that regulates or accelerates the rate of a chemical reaction without itself undergoing a permanent change.

cataplexy a condition of muscular rigidity induced by severe mental shock or fear. The patient remains conscious.

cataract opacity of the lens of the eye causing partial or complete blindness. Usually age-related, but many causes including congenital, traumatic or metabolic such as diabetes mellitus.

catarrh chronic inflammation of a mucous membrane with constant flow of a thick sticky mucus.

catecholamines a group of important physiological amines, such as adrenaline (epinephrine), noradrenaline (norepinephrine) and dopamine. They act as hormones and neurotransmitters and affect blood pressure, heart rate, respiratory rate and blood sugar. Abnormally high levels are secreted by adrenal and other tumours and can be detected in the urine. See also phaeochromocytoma.

categorical data data that can be categorized, for example, hair colour. See also nominal data, ordinal data.

CAT scanner computer assisted tomography or computed axial tomography. See also CT scanner.

cat scratch fever a virus infection resulting from a cat scratch or bite. There is fever and lymph node swelling about a week after the incident. Recovery is usually complete, although an abscess may develop.

catheter a hollow tube of variable length and bore, usually having one fluted end and a tip of varying size and shape according to function. Catheters are made of many substances including soft and hard rubber, gum elastic, glass, silver, other metals and plastic materials, some of which are radiopaque. They have many uses including: blowing gas, air or powder into a cavity, cardiac catheterization, introduction of contrast agent for angiography, withdrawal of fluid from body cavities, for example, urinary catheter and the administration of drugs, fluids and nutrients.

catheterization insertion of a catheter, most usually into the urinary bladder. See also cardiac catheterization.

cathetron unit a high-rate dose, remotely controlled, afterloading device for radiotherapy. Hollow steel catheters are placed in the desired position. They are then connected to a protective safe by hollow cables. The radioactive cobalt moves from the safe into the catheters. After delivery of the required dose, the cobalt returns to the safe, thus avoiding radiation hazard to staff. Currently superseded by units such as the Selectron.

cathode is the assembly that contains the negatively charged filament, focussing cup, supporting wires and cathode support in an X-ray tube.

cathode rays streams of electrons coming from the heat filament or cathode.

cathode ray tube used in older computer monitors where an electron gun is focussed on a fluorescent screen, where electrons hit the screen light is produced and therefore an image is formed. See also glass plasma display, liquid crystal display.

cation a positively charged ion which moves towards the cathode when an electric current is passed through an electrolytic solution. See also anion.

cauda a tail or tail-like appendage.

cauda equina lower part of the spinal cord where the nerves for the legs and bladder originate.

caudad towards the feet.

caudal anaesthesia injection of local anaesthetic into the epidural space at the level of the sacrum causing loss of sensation in the lower abdomen and pelvis.

cauterize to cause tissue destruction by applying a heated instrument.

cautery an agent or device, for example, electricity, chemicals or extremes of temperature, which destroys cells and tissues. Uses include the prevention of blood loss during surgery, or to remove abnormal tissue.

cavernous having hollow spaces.

cavernous sinus a channel for venous blood, on either side of the sphenoid bone. It drains blood from the cerebral hemispheres, orbits and the bones of the skull. Sepsis around the eyes or nose can cause cavernous sinus thrombosis.

cavitation the formation of a cavity, as in pulmonary tuberculosis. When gas bubbles expand, contract, increase in pressure or temperature due to the passage of ultrasound.

cavity a hollow; an enclosed area.

CDROM (Compact Disk Read-Only Memory) an object for storing computer data; once the data have been stored they cannot be changed.

CDRW (Compact Disk Re-Writer) an object for storing computer data; the data can be re-written if required.

celestin tube a soft rubber intubation tube which is pulled through an oesophageal tumour by the use of a string or guidewire and is attached to the stomach with a suture. Used to maintain a free passage of food and fluid.

cell basic structural unit of living organisms. A mass of protoplasm (cytoplasm) and usually a nucleus within a plasma or cell membrane. Some cells, for example, erythrocytes, are non-nucleated whereas others, such as voluntary muscle, may be multinucleated. The cytoplasm contains various subcellular organelles – mitochondria, ribosomes, etc. – that undertake the metabolic processes of the cell.

cell cycle the events occurring within a cell from one mitotic division to the next. Comprises the dynamic course of division of normal and cancer cells incorporating phases of DNA synthesis (S-phase), growth phases (GI and GII), mitosis (M) and ‘rest phase’ (G0).

cell cycle phase non-specific describes a cytotoxic drug that acts at any time in the cell cycle.

cell cycle phase specific describes a cytotoxic drug that acts during a specific phase of the cell cycle.

Celsius the derived SI unit (International System of Units) for temperature. Named after Anders Celsius (1701–1744) who constructed the first centigrade thermometer. See also centigrade.

cement the outer layer covering the root of a tooth and continuous with the enamel.

cementum calcified organic hard tissue forming on the surface of a root of a tooth, and providing attachment for the periodontal ligament.

Centers for Disease Control and Prevention (CDC) a federal agency in the USA (Atlanta). Its functions include the investigation, identification, prevention and control of disease.

centigrade a scale with one hundred divisions or degrees. Most often refers to the thermometric scale in which the freezing point of water is fixed at 0öC and the boiling point at 100öC. It is usually called Celsius for medical and scientific purposes. See also Celsius.

central limit theorem in research: sampling distribution becomes more normal the more samples that are taken.

central sterile supplies department (CSSD) designated an area where packets are prepared containing the equipment and/or swabs and dressings necessary to perform activities requiring aseptic technique. See also hospital sterilization and disinfection unit (HSDU).

central tendency statistic averages. The tendency for observations to centre around a specific value rather than across the entire range. See also mean, median, mode.

central venous catheter/line specialized intravenous cannula placed in a large vein (jugular, subclavian or femoral). Used for the measurement of central venous pressure, and fluids and drugs. Also allows long-term vascular access for the administration of drugs, blood products or nutritional support.

central venous pressure (CVP) the pressure of the blood within the right atrium. It is measured using a central venous catheter attached to a manometer or pressure transducer.

centralized daylight system a system where the loading and unloading of a cassette or film magazine is directly linked to an automatic film processor.

centric occlusion contact of the upper and lower teeth with maximum contact of the cusps.

centrifugal efferent. Having a tendency to move outwards from the centre, as the nerve impulses from the brain to the peripheral structures.

centrifuge an apparatus which subjects solutions to centrifugal forces by high-speed rotation, thereby separating substances of different densities into discrete bands within the liquid phase. It is usually used to separate (‘spin down’) particulate material (for example, subcellular particles) from a suspending liquid.

centriole a subcellular organelle that aids spindle formation during nuclear division. See also meiosis, mitosis.

centronics a type of standard interface between computer and peripheral.

cephalalgia pain in the head; headache.

cephalic associated with the head; near the head.

cephalocele hernia of the brain; protrusion of part of the brain through the skull.

cephalometric radiograph a lateral projection of the skull and mandible for making cranial measurements to estimate the degree of any facial abnormality.

cephalometry measurement of the living human head.

ceramic detector a modern device used in CT scanning to measure the amount of radiation transmitted through a patient, giving a reduction in noise compared with earlier detectors and in chest scans there is said to be a reduction in beam hardening artefacts.

cerebellar gait a staggering, unsteady, wide-based walk seen in patients with damage to the cerebellum or its connections. See also gait.

cerebellum that part of the brain which lies behind and below the cerebrum. Its chief functions are the coordination of fine voluntary movements and the control of posture.

cerebral associated with the cerebrum.

cerebral cavity the ventricles of the brain.

cerebral compression arises from any space-occupying intracranial lesion.

cerebral cortex the outer layer of cells (grey matter) in the cerebral hemispheres.

cerebral hemisphere one side of the cerebrum, right or left.

cerebral palsy non-progressive brain damage that typically occurs at, or shortly after, birth resulting in a range of mainly motor conditions ranging from clumsiness to severe spasticity.

cerebral function monitor (CFM) equipment for continuous monitoring of brain wave activity, for example, to detect seizures in sedated and paralysed patients.

cerebral perfusion pressure (CPP) the pressure which drives blood through the brain. It is the difference between the arterial blood pressure and the intracranial pressure. If CPP is too low the blood flow to the brain may be inadequate and the brain deprived of oxygen.

cerebrospinal associated with the brain and spinal cord.

cerebrospinal fluid the clear fluid found within the ventricles (cavities) of the brain, central canal of the spinal cord and beneath the cranial and spinal meninges in the subarachnoid space. Protects and nourishes the brain and spinal cord. It is formed by the choroid plexus in the ventricles and circulates around the brain and spinal cord before it is reabsorbed on the outside of the brain.

cerebrovascular associated with the blood vessels of the brain.

cerebrovascular accident (stroke) (CVA) interference with the cerebral blood flow due to embolism, haemorrhage or thrombosis. Signs and symptoms vary according to the duration, extent and site of tissue damage; there may be only a passing, even momentary inability to move a hand or foot; weakness or tingling in a limb; stertorous breathing; incontinence of urine and faeces; coma; paralysis of a limb or limbs; and speech deficiency (aphasia). See also transient ischaemic attack.

cerebrum the largest and uppermost part of the brain. The longitudinal fissure divides it into two hemispheres, each containing a lateral ventricle. A mass of nerve fibres (white matter) is covered by a thin layer of nerve cells (grey matter). It controls the higher functions and contains major motor and sensory areas. The outer surface is convoluted.

cerumen ear wax, sticky brown secretion from glands in the external auditory canal. Traps dust and other particles entering the ear.

cervical associated with the neck. Associated with the cervix (neck) of an organ.

cervical canal the lumen of the cervix uteri, from the internal to the external os.

cervical intraepithelial neoplasm (CIN) abnormal changes in the basal layer of the squamous epithelial layers of the uterus and is divided into three grades, CIN 1 is pre-malignant through to CIN3 which is early cancer.

cervical rib an additional rib articulating with the seventh cervical vertebra.

cervical smear see cervical intraepithelial neoplasia.

cervical vertebrae the seven bones that form the neck.

cervicectomy amputation of the uterine cervix.

cervicitis inflammation of the uterine cervix.

cervix a neck.

cervix uteri uterine cervix, the neck of the uterus.

cetrimide a disinfectant with detergent properties. Used for wound cleansing and skin preparation.

chancre the primary syphilitic ulcer developing at the site of infection with Treponema pallidum. It is associated with swelling of local lymph nodes. The chancre is painless, hard (indurated), solitary and highly infectious.

characteristic curve applies to a particular film or film/screen combination and is the curve which results when the density is plotted against the log of relative exposure. It is also called D log E curve, a Hurter and Driffield curve, a log It curve. The curve is used to determine the basic fog level, threshold, toe, straight line portion, shoulder and maximum density of the film. See also basic fog level, threshold, toe, straight line portion, shoulder, maximum density. (See figure on p. 80).

charcoal used therapeutically for its adsorptive and deodorant properties. Can be taken to absorb abdominal gas. Activated charcoal incorporated into dressings is used to reduce odour in discharging wounds.

Charcot’s joint complete disorganization of a joint associated with fluid-filled cavities in the spinal cord (syringomyelia), diabetes mellitus, or advanced cases of wasting away of the posterior nerve roots of the spinal cord (tabes dorsalis, locomotor ataxia). The condition is painless.

CHART

continuous hyperfractionated accelerated radiotherapy.

chelate a compound composed of a central metal ion and an organic molecule with multiple bonds, formed in a ring formation.

chemonucleolysis injection of an enzyme, usually into an intervertebral disc, for dissolution of same.

chemoradiation giving chemotherapy and radiotherapy at the same time.

chemoreceptor a sensory nerve ending or a cell having an affinity for, and capable of reacting to, a chemical stimuli, for example, taste, oxygen levels in the blood.

chemoresistant describes a tumour that does not usually shrink with chemotherapy.

chemosensitive describes a tumour that shrinks following chemotherapy administration.

chemotaxis movements of a cell (for example, leucocyte) or a microorganism in response to chemical stimuli; attraction is termed positive chemotaxis, repulsion is negative.

chemotherapy chemical agents of various types; prescribed to delay or arrest growth of cancer cells through interruption/inhibition of cell cycle; on a selective basis by impairing their ability to replicate. Usually given in combination rather than as single agents. They are non-selective and non-specific and therefore affect all cycling cells whether benign or malignant. Administration is by oral, intramuscular, intravenous, intracavitary, or intra-arterial routes. See also alkylating agents, antimetabolites, antitumour antibiotics, vinca alkaloids.

chenodeoxycholic acid a bile acid. It can be taken orally to dissolve certain types of gallstones.

Cheyne–Stokes respiration a cyclic pattern of irregular breathing followed by an absence of breathing for about 15 seconds, occurring in patients with cerebral disease, especially when there is increased intracranial pressure.

chi-square test a statistical test used to compare groups to see if the behaviour of one of the groups is significant. A chi-square table is used and the results must be equal to or greater than the value given in the table to be significant.

chiasma an X-shaped crossing or crossing of nerve fibres (decussation). See also optic chiasma.

child abuse physical, sexual or emotional abuse or neglect of children by relatives or health and social care staff. See also non-accidental injuries.

chip a piece of silicon or gallium arsenide which contains the microcircuitry which operates the computer.

chiropractic a technique of spinal manipulation, based on the principle that defects in vertebral alignment may result in various problems caused by functional changes in the nervous system.

chiropractor a person who uses chiropractic techniques.

chi-square statistic (χ²) a technique used to analyse the relationship between expected frequency and the actual frequency of data obtained. A test of statistical significance used to determine the probability of results occurring by chance. See also non-parametric tests.

chlorhexidine a disinfectant solution which is effective against a wide range of bacteria. Used for general skin cleansing and disinfection, and hand decontamination, etc.

chloride a salt of hydrochloric acid. A major anion in extracellular fluid.

chlorine a greenish-yellow, irritating gaseous element. Powerful disinfectant, bleaching and deodorizing agent in the presence of moisture when nascent oxygen is liberated. Mainly used as hypochlorites, or other compounds which slowly liberate active chlorine.

chloroform a heavy liquid, once used extensively as a general anaesthetic. Used as chloroform water as a flavouring and preservative in aqueous mixtures.

choanae funnel-shaped openings. See also nares.

cholangiography rarely performed radiographic examination of hepatic, cystic and bile ducts. Can be performed: (a) after oral or intravenous administration of a radiographic contrast agent, (b) by direct injection at operation to detect any further stones in the ducts, (c) during or after operation by way of a T-tube in the common bile duct, (d) by means of an injection via the skin on the anterior abdominal wall and the liver, when it is called percutaneous transhepatic cholangiography (PTC). See also endoscopic retrograde cholangiopancreatography.

cholangitis inflammation of the bile ducts.

cholecystectomy surgical removal of the gallbladder. See also laparoscopic cholecystectomy.

cholecystenterostomy literally, the establishment of an artificial opening (anastomosis) between the gallbladder and the small intestine. Specific terminology more frequently used.

cholecystitis inflammation of the gallbladder.

cholecystoduodenal associated with the gallbladder and duodenum as an anastomosis between them.

cholecystoduodenostomy the establishment of an artificial connection (anastomosis) between the gallbladder and the duodenum.

cholecystography rarely performed radiographic examination of the gallbladder after administration of opaque contrast agent. Superseded by CT and MRI.

cholecystojejunostomy an artificial connection (anastomosis) between the gallbladder and the jejunum.

cholecystokinin (CCK) a hormone that contracts the gallbladder and relaxes the sphincter of Oddi thus allowing bile into the duodenum, and stimulates the secretion of pancreatic enzymes. Secreted by the duodenal mucosa.

cholecystolithiasis the presence of stone or stones in the gallbladder.

cholecystostomy a surgically established fistula between the gallbladder and the abdominal surface; used to provide drainage, in a collection of pus (empyema) in the gallbladder.

cholecystotomy incision into the gallbladder.

choledochoduodenal associated with the bile ducts and duodenum, for example, choledochoduodenal fistula.

choledochography see cholangiography.

choledochojejunostomy an anastomosis between the bile duct and the jejunum.

choledocholithiasis the presence of a gallstone or gallstones in the extrahepatic bile ducts.

choledocholithotomy surgical removal of a stone from the common bile duct.

choledochoscopy endoscopic examination of the biliary tree.

choledochostomy drainage of the common bile duct using a T-tube, usually after exploration for a stone.

choledochotomy incision into the common bile duct.

cholelithiasis the presence or formation of gallstones in the gallbladder or bile ducts.

cholestasis an obstruction to the flow of bile. It produces jaundice, dark urine, pale stools, metallic taste and pruritus. See also extrahepatic cholestasis, intrahepatic cholestasis.

cholesteatoma a benign encysted tumour containing squamous epithelial debris. Mainly occurs in the middle ear.

cholesterol a sterol found in many tissues. It is an important component of cell membranes and is the precursor of many biological molecules, such as steroid hormones. High levels in the blood are linked with the development of arterial disease and some types of gallstones. See also hypercholesterolaemia.

cholesterosis abnormal deposition of cholesterol.

cholic acid a bile acid.

chondritis inflammation of cartilage.

chondroblastoma a benign tumour that usually develops in the epiphyses of the femur and humerus.

chondrocostal associated with the costal cartilages and ribs.

chondrodynia pain in a cartilage.

chondrolysis dissolution of cartilage.

chondroma a benign tumour of cartilage.

chondromalacia softening of cartilage.

chondrosarcoma malignant tumour of cartilage.

chondrosternal associated with the costal cartilages and sternum.

chordoma a rare tumour that develops in the fetal notochord.

choriocarcinoma (chorionepithelioma) a malignant tumour of chorionic cells; develops following normal pregnancy (rarely), miscarriage or evacuation of a hydatidiform mole. A sensitive (though not specific) tumour marker is human chorionic gonadotrophin (HCG). Choriocarcinoma is usually chemosensitive and curable.

chorion the outer membrane forming the sac that contains the amniotic fluid and the fetus.

chorion biopsy see amnion, chorionic villus sampling.

chorionepithelioma see choriocarcinoma.

chorionic associated with the chorion. chorionic gonadotrophin. See also human chorionic gonadotrophin.

chorionic villi vascular projections from the chorion from which the fetal part of the placenta is formed. Through which substances such as nutrients and waste diffuse between maternal and fetal blood and vice versa.

chorionic villus sampling (CVS) also known as chorion biopsy or chorionic villus biopsy. A prenatal screening test for chromosomal and other inherited disorders. Samples of fetal tissue are obtained using the transabdominal or transcervical approach for the detection of genetic abnormalities during early pregnancy done after 10 weeks to avoid the potential risk of limb malformations.

choroid the middle pigmented, vascular coat of the posterior five-sixths of the eyeball, continuous with the iris in front. It lies between the sclera externally and the retina internally, and prevents the passage of light rays.

choroid plexus specialized capillaries in the cerebral ventricles that produce cerebrospinal fluid.

chromatic aberration the non-convergence of different coloured rays in a lens.

chromatid one of the strands that result from the duplication of chromosomes during nuclear division.

chromatid aberrations caused when cells are irradiated after the DNA replication phase.

chromatin the threads of DNA and protein that form the substance of chromosomes.

chromatography a method of chemical analysis by which substances in solution can be separated from each other. Includes: gel filtration chromatography, gas chromatography and ion exchange chromatography.

chromosomal aberration loss, gain or exchange of genetic material in the chromosomes of a cell resulting in deletion, duplication, inversion or translocation of genes.

chromosome the genetic material present in the nucleus of the cell. During the preparation for cell division chromosomes appear as microscopic threads. They contain strands of DNA molecules or genes. Each species has a constant number; humans have 23 pairs (46) in each somatic cell: 22 pairs of autosomes and 1 pair of sex chromosomes (males have XY and females have XX). Mature gametes, however, have half the usual number (haploid) which results from the reduction division during meiosis. The 23 unpaired chromosomes inherited from each parent unite to produce an embryo with 46 chromosomes (diploid). Genetic sex is determined by the male gamete and depends on whether the oocyte is fertilized by a sperm that contributes a Y chromosome (genetic male) or an X chromosome (genetic female). Some genetic material is also present in organelles, such as the mitochondria. See also meiosis, mitosis.

chromosome aberrations DNA damage caused when cells are irradiated in the G₁ phase of the cell cycle.

chronic lingering, lasting, opposed to acute. The word does not imply anything about the severity of the condition.

chronic fatigue syndrome see benign myalgic encephalomyelitis.

chronic heart failure see congestive heart failure.

chronic leukaemia see leukaemia.

chronic obstructive airways disease (COAD) group of obstructive lung diseases in which airway resistance is increased with impaired airflow. See also chronic obstructive pulmonary disease (COPD).

chronic obstructive pulmonary disease (COPD) group of obstructive lung diseases where airway resistance is increased with impaired airflow, for example, pulmonary emphysema and chronic bronchitis. Defined on spirometric grounds as an FEV₁ < 80% and an FEV1:FVC ratio < 70%. Usually seen as a long-term sequela of smoking. Genetic factors include α1-antitrypsin deficiency, and more recently, family clustering studies suggest other genetic susceptibility factors.

chronological age a person’s age in years.

chronotherapy the administration of treatment, such as chemotherapy or radiotherapy, at the most effective time.

chyle fatty, milky fluid formed from chylomicrons within the lymphatic lacteals of the intestinal villi.

chylomicron tiny particles formed from triglycerides, lipoproteins and cholesterol and lipoproteins within the intestinal mucosa following the absorption of digested fat. They form chyle within the lacteals.

chyme partially digested food which is acidic passes from the stomach to the duodenum. Its acidity controls the pylorus to regulate the amount entering the duodenum.

chymotrypsin an inactive proteolytic enzyme secreted by the pancreas: it is activated by trypsin.

cilia the eyelashes. Microscopic hair-like projections from certain epithelial cells. Membranes containing such cells, for example, those lining the trachea and uterine (fallopian) tubes, are known as ciliated membranes.

ciliary hair-like.

ciliary body a specialized structure in the eye connecting the anterior choroid to the iris, it is composed of the ciliary muscles and processes.

ciliary muscles fine muscle fibres arranged in a circular manner. They control accommodation.

ciliary processes about 70 in number, they secrete aqueous humour.

circadian rhythm any rhythm with a period of 24 hours.

circulation passage in a circle. Usually means circulation of the blood. See also pulmonary circulations, systemic circulation.

circulation of bile see enterohepatic circulation.

circulation of blood the passage of blood from heart to arteries to capillaries to veins and back to heart.

circulation of cerebrospinal fluid takes place from the ventricles of the brain to the cisterna magna, whence the fluid bathes the surface of the brain and the spinal cord, including its central canal. It is absorbed into the blood in the cerebral venous sinuses.

circulation of lymph lymph is collected from the tissue spaces and passed in the lymphatic capillaries, vessels, nodes and ducts to be returned to the bloodstream.

circumduction a combination of the movements of flexion, extension, abduction, adduction and internal and external rotation. For example the movement in the shoulder joint when the arm moves in a circle.

circumferential lamellae rings of bone round the edge of a long bone.

circumvallate surrounded by a raised ring, as the large circumvallate papillae at the base of the tongue.

cirrhosis hardening of an organ. There are degenerative changes in the tissues with resulting fibrosis. Cirrhosis of liver is increasing in prosperous countries. Damage to liver cells can be from viruses, other microorganisms or toxic substances and dietary deficiencies interfering with the nutrition of liver cells, often the result of alcohol misuse. Associated developments include ascites, obstruction of the circulation through the hepatic portal vein with haematemesis, jaundice and enlargement of the spleen.

cisterna any closed space serving as a reservoir for a body fluid.

cisterna chyli the pear-shaped commencement of the thoracic duct. It receives lymph. cisterna magna is a subarachnoid space in the cleft between the cerebellum and medulla oblongata.

cisternal puncture insertion of a special hollow needle with stylet between the occiput and atlas, into the cisterna magna. One method of obtaining cerebrospinal fluid but rarely used. See also lumbar puncture.

cisternography the injection of a radionuclide into the subarachnoid space via a lumbar puncture. The radionuclide concentrates in the ventricles, demonstrates, communicating hydrocephalus, cerebrospinal fluid shunts and fistulae.

civil law law relating to non-criminal matters. Civil action proceedings brought in the civil courts. Civil wrong act or omission which can be pursued in the civil courts by the person who has suffered the wrong.

classical scattering see coherent scattering.

classified person an employee who is likely to receive a dose of ionizing radiation which exceeds three-tenths of any relevant dose limit.

claustrophobia fear of confined places.

clavicle the collar bone.

clavus a corn. See also callus.

claw-foot see pes cavus.

claw-hand the hand is flexed and contracted giving a claw-like appearance; the condition may be due to injury or disease.

cleanser (describes) agents that have cleansing properties. Drugs such as cetrimide are both disinfectant and cleansing. Used to remove dirt, grease, etc., from the skin or wounds, and for removing crusts and other debris from skin lesions.

clearance the ability of the kidney to remove a specific substance from the blood. renal clearance used to measure glomerular filtration rate and kidney function by calculating the volume of blood cleared of a substance such as creatinine, in a given time, usually 1 minute.

clear-based films have no dye in the base and have a low base fog and are particularly suited for ultrasound imaging.

clearing time the time taken in a fixer solution for the unexposed areas of the film to become transparent.

cleft lip a congenital defect in the lip; a fissure extending from the margin of the lip to the nostril; may be single or double, and is often associated with cleft palate.

cleft palate congenital failure of fusion between the right and left palatal processes. Often associated with cleft lip.

client quality the patient’s view of how well the service or product provides what is expected by the patient.

clinical audit critical and systematic analysis of the quality of clinical care and treatment. It includes diagnostic procedures, treatment, resource use and outputs including quality of life.

clinical governance the framework within which all NHS organizations are accountable for their services, and are required to operate an active programme of continuous quality improvement within an overall, coherent framework of cost-effective service delivery.

clinical guidelines systematically developed statements that help the practitioner and patient in making decisions about care. See also evidence-based practice.

clinical target volume the total treatment field in relation to the tumour in radiotherapy.

clinical thermometer previously, glass and mercury thermometers of various types were used to take a patient’s temperature. These have mostly been replaced by safer alternatives, such as electronic probes, for example, tympanic membrane thermometers, and single-use thermometers.

clinodactyly incurving of a finger, usually the fifth.

clitoris a small erectile organ situated at anterior junction of the labia minora. Involved in the female sexual response.

cloaca the common intestinal and urogenital opening found in many vertebrates. In osteomyelitis, the opening through newly formed bone from a diseased area to enable pus to discharge.

clonal derived from a single cell.

clonogenic cell a cell that can proliferate into a colony of genetically identical cells.

clonus a series of intermittent muscular contractions and relaxations.

closed fracture a broken bone where the skin surface is intact.

closed manipulation a method of manually realigning broken bones under general anaesthetic without the use of surgery.

clubbed fingers a thickening and broadening of the bulbous fleshy portion of the fingers under the nails. The cause is not known but it occurs in people who have chronic heart and/or lung disease.

club foot a congenital malformation, either unilateral or bilateral. See also talipes.

Clutton’s joints joints which show symmetrical swelling usually painless, the knees often being involved. Associated with congenital syphilis.

coagulation the third of four overlapping processes involved in haemostasis. Coagulation (clotting) occurs through a series of complex reactions that use enzyme cascade amplification to start the formation of a fibrin clot to stop bleeding. There are two pathways/systems, intrinsic and extrinsic, which converge to follow a common final pathway. Coagulation starts when platelets break down, tissue is damaged and thromboplastins are released. Various factors are involved in coagulation: I, fibrinogen; II, prothrombin; III, tissue thromboplastin; IV, calcium ions; V, labile factor (proaccelerin); VII, stable factor (proconvertin); VIII, antihaemophilic factor (AHF); IX, Christmas factor; X, Stuart–Prower factor; XI, plasma thromboplastin antecedent; XII, Hageman factor; and XIII, fibrin-stabilizing factor. During the final common pathway, inactive prothrombin is converted to thrombin, the active enzyme. Thrombin converts soluble fibrinogen to insoluble fibrin, which forms a network of fibres in which blood cells are caught to form the clot. See also haemostasis, platelet plug.

coarctation contraction, stricture, narrowing; applied to a vessel or canal. coarctation of the aorta congenital narrowing of the aorta, commonly affecting the area just after the origin of the left subclavian artery.

coating weight the amount of phosphor per unit volume in a radiographic intensifying screen.

cobalt (Co) an essential trace element, utilized as a constituent of vitamin B₁₂ (cobalamins). Required for healthy red blood cell production and proper neurological function.

cobalt-60 a radioactive isotope of cobalt which is used as a source of radiation in teletherapy.

cobalt unit a radiotherapy machine housing the isotope cobalt-60, the resultant radiation delivers the maximum dose below the skin surface and therefore reduces the likelihood of skin reactions.

cocaine a powerful local anaesthetic obtained from the leaves of the coca plant. It is a controlled drug which is highly addictive and subject to considerable criminal misuse. Toxic, especially to the brain; may cause agitation, disorientation and convulsions. crack cocaine a highly potent and addictive form.

coccus a spherical bacterium.

coccydynia pain in the region of the coccyx.

coccygectomy surgical removal of the coccyx.

coccyx the last bone of the vertebral column. It is composed of four or five rudimentary vertebrae, cartilaginous at birth, ossification being completed at about the 30th year.

cochlea a spiral canal resembling the interior of a snail shell, in the anterior part of the bony labyrinth of the ear.

Cockcroft–Walton generator utilizes a number of rectifiers and capacitors, connected in series to produce a fully rectified voltage with less than 0.2% ripple. A single unit can cover the low-energy therapeutic X-ray range but for medium energy radiotherapy machines two units are used back to back. A voltage multiplier circuit using diodes and capacitors used in some X-ray generator systems.

code of practice the guidelines setting out how healthcare professionals should fulfil their roles, duties, obligations and responsibilities, such as those produced by the statutory bodies whose functions are to regulate the registration and practice of healthcare professionals, for example, General Medical Council.

coeliac relating to the abdominal cavity; applied to arteries and a nerve plexus.

coeliac disease (gluten-induced enteropathy) due to intolerance to the protein gluten in wheat and rye. This results in subtotal villous atrophy of the mucosa of the small intestine and the malabsorption syndrome. Symptoms may become apparent at any age or patients may be asymptomatic. Treatment is with gluten-free diet.

coffee ground vomit vomit containing blood, which in its partially digested state resembles coffee grounds. Indicative of slow upper gastrointestinal bleeding. See also haematemesis.

cognitive the mental process of comprehension, judgement, memory and reasoning as opposed to emotional processes.

coherent scattering when a photon interacts with an electron, is deflected from its path but does not lose energy. See also elastic scattering.

cohort a group of people who have some common feature or characteristic, for example, year group at university.

cohort study research that studies a population that shares a common feature, such as occupation.

coil single or multiple loops of wire designed to produce (or transmit) a magnetic field when current flows through the wire or measure (or receive) an induced voltage in the loop caused by a changing magnetic field. See also induction, transformer.

coitus insertion of the erect penis into the vagina; the act of sexual intercourse or copulation.

coitus interruptus removal from the vagina of the penis before ejaculation of semen as a means of contraception. The method is considered unsatisfactory as it is not only unreliable but can lead to sexual disharmony.

cold spot a term used in radionuclide imaging when a lower than expected quantity of radiation is detected.

cold water processor an automatic film processor that only has a cold water supply and is more energy efficient than processors that use hot and cold water.

colectomy excision of part or the whole of the colon.

colic severe pain resulting from periodic spasm in an abdominal organ. intestinal colic abnormal peristaltic movement of an irritated gut. renal colic spasm of ureter due to the presence of a stone. biliary colic spasm of the biliary system due to the presence of a stone.

coliform describes any of the enterobacteria (intestinal bacteria) such as Escherichia coli.

colitis inflammation of the colon. May be acute or chronic, and may be accompanied by ulcerative lesions. See also inflammatory bowel disease, ulcerative colitis.

collagen the main protein constituent of white fibrous tissue of skin, tendon, bone, cartilage and all connective tissue.

collagen diseases there is inflammation of unknown aetiology affecting collagen and small blood vessels. They involve autoimmune responses and include dermatomyositis, polyarteritis nodosa, rheumatoid arthritis, scleroderma and systemic lupus erythematosus (SLE).

collapse the ‘falling in’ of a hollow organ or vessel, for example, collapse of lung from change of air pressure inside or outside the organ. A vague term describing physical or nervous prostration.

collapsing pulse also known as Corrigan’s pulse. The water-hammer pulse of aortic regurgitation with high initial upthrust which quickly falls away.

collar bone the clavicle.

collateral circulation an alternative route provided for the blood by secondary blood vessels when a primary vessel is blocked.

collecting tubule straight tube in the kidney medulla conveying urine to the renal pelvis.

Colles’ fracture a break at the lower end of the radius and ulna following a fall on the outstretched hand. The backward displacement of the radius produces the ‘dinner fork’ deformity. A common fracture in older women and associated with osteoporosis.

collimate literally to make parallel. Restriction of the X-ray beam to a particular area. In CT this may be done pre patient or pre and post patient. pre-patient collimation restricts the incident beam to the required body area, determining the data set to be acquired. Post-patient collimation restricts scatter reaching the detectors: primarily on single slice units.

collimation the restriction of the size of an X-ray beam to minimize radiation dosage.

collimator a device for defining the size of the beam from an X-ray tube. primary collimator defines the maximum available beam size; the secondary collimators can be adjusted to restrict the field size to the treatment area in radiotherapy or the image size in diagnostic radiography. A device on a gamma camera designed to accurately project an image of radioactive distribution received from the patient on to the scintillator. See also parallel-hole collimator, pin-hole collimator, converging collimator.

collision in computing a collision occurs if two computers access the network at the same time.

collodion a solution forming a flexible film on the skin. Previously used as a protective dressing.

colloid glue-like. A non-crystalline chemical; diffusible but not soluble in water; unable to pass through a semipermeable membrane. Some drugs can be prepared in their colloidal form.

colloid degeneration that which results in the formation of gelatinous material, as in tumours.

colloid goitre enlargement of the thyroid gland caused by the presence of viscid, iodine-containing colloid within the gland.

colloid solutions ones containing large molecules used intravenously in the treatment of shock.

colon the large bowel extending from the caecum to the rectum. Comprises the ascending, transverse, descending and sigmoid colon. See also flexure, megacolon.

colonic lavage the washing out of the colon by using an enema, to empty the bowel prior to an examination or operation.

colonic washout a method of clearing the bowel of faecal matter.

colonoscopy the examination of the colon by the insertion of a fibreoptic instrument.

colony a mass of bacteria resulting from the multiplication of one or more microorganisms. Containing many millions of individual micro-organisms it may be visible to the unaided eye; its physical features are often characteristic of the species.

colorectal associated with the colon and the rectum.

colostomy a surgically established fistula between the colon and the surface of the abdomen; to form either a temporary or permanent artificial anus (stoma) that discharges faeces.

colotomy incision into the colon.

colour depth the maximum number of colours a computer monitor is able to display and is determined by the bit depth, with 16 giving good colour and 24 giving true colour.

colour flow Doppler the simultaneous ultrasound display of anatomical and flow information. Anatomy is shown as a grey scale image and blood flow in colour, for example, blood flowing towards the transducer is usually in red and away from the transducer is usually displayed in blue.

colour sensitizing increasing the spectral sensitivity of the film by adding impurities to the film emulsion. See also spectral sensitizing.

colpocele protrusion or prolapse of either the bladder or rectum so that it presses on the vaginal wall.

colpohysterectomy removal of the uterus through the vagina. See also hysterectomy.

colpophotography filming the cervix using a camera and colposcope.

colporrhaphy surgical repair of the vagina. An anterior colporrhaphy repairs a protrusion of the bladder through the wall of the vagina (cystocele) and a posterior colporrhaphy repairs a protrusion of the rectum and posterior wall of the vagina into the vagina (rectocele).

colposcope a binocular instrument used to obtain a high-power view of the cervix in cases of abnormal cervical smears. Used for diagnostic procedures and local treatments to the cervix.

colposcopy the examination of the cervix using light and magnification.

coma a state of unconsciousness from which the patient cannot be aroused, the severity can be assessed by corneal and pupillary reflexes and withdrawal responses to painful stimuli.

comet tail artefact multiple reflections of ultrasound usually produced by small artefacts, usually in the gall bladder wall.

comminuted fracture a break in a bone where the bone is fragmented.

Commission for Healthcare Audit and Inspection (CHAI) (Healthcare Commission) a body with statutory powers to inspect and support the implementation of clinical governance arrangements in NHS Trusts. Their remit also includes targeted support when requested by organizations with a specific problem, and in more serious situations they may intervene by direction of the Secretary of State or at the request of Strategic Health Authorities, NHS Trusts or Primary Care Trusts. Also responsible for the second stage of the NHS Complaints procedure.

commissioning a complex process that aims to ensure that a specific population has an appropriate level of service provision. The stages include a needs assessment that is used to determine priorities, taking into account the overall national policy guidance from government. On completion of this process, an appropriate range of services are purchased from relevant providers. The final stage is evaluation.

commissioning tests checks made on new radiotherapy equipment to ensure that it is safe to treat patients; tests include radiation protection, leakage, accuracy of beam direction devices, beam modalities and output dose calibration.

committed dose the absorbed dose of radiation an individual receives as the result of the intake of radioactive material.

Committee on Safety of Medicines (CSM) in the UK the body that monitors drug safety and advises the licensing authority regarding the safety, efficacy and quality of medicines.

common variable immunodeficiency (CVID) one of the primary antibody deficiency syndromes, presenting in children or adulthood and associated with recurrent infections, autoimmunity, and an increased risk of malignancy.

communicable transmissible directly or indirectly from one person to another.

community care the care and support of individuals in community settings. Such care is delivered by health and social care professionals and unpaid carers such as family and neighbours. The community or primary care setting is increasingly important in the development and delivery of health services. See also Primary Care Trust.

comorbidity coexistence of two or more diseases.

compact bone the type of dense bone containing cylindrical structures called haversian systems which is found mainly in the shafts of long bones.

compact disk (CD) a 120-mm sheet of aluminium covered with a layer of acetate and with a polycarbonate backing. Used in computing to store data in digital form which can be read by a laser.

comparative study research study that compares two separate populations.

compartment syndrome swelling of the muscles in one of the limb compartments leading to ischaemia and necrosis of muscle tissue. Treatment is incision of the muscle fascia (fasciotomy).

compatibility suitability; congruity. The ability of a substance to mix with another without unfavourable results, for example, two medicines, blood plasma and cells.

complemental air the extra air that can be drawn into the lungs by deep inspiration.

complete abortion a termination of pregnancy or a miscarriage when all the products of conception are expelled or removed.

complete miscarriage the entire contents of the uterus are expelled.

complicated fracture a break in bone continuity with associated injury of an organ or vessel.

complication in medicine, an accident or second disease arising in the course of a primary disease; it can be fatal.

compound a substance composed of two or more elements, chemically combined in a definitive proportion to form a new substance which displays new properties.

compound filters beam-hardening filters made of tin, copper and aluminium used in radiotherapy. To be effective the filters must be fitted in the correct order, with those of the highest atom number nearest the target and the lowest nearest the patient.

compound (open) fracture where part of the fracture is in contact with the external surface of the body.

compress usually refers to a folded pad of lint, gauze or other material used to arrest haemorrhage or apply pressure, cold, heat, moisture or medication. Used to reduce swelling or pain, such as a cold compress to ease a headache.

compression the state of being compressed. Pressing or squeezing together.

compression band in radiography, an immobilization device which also displaces body tissue laterally and therefore enables a reduction in radiographic exposure factors and as a result radiation dose to the patient.

compression bandage/therapy used in the management of venous leg ulcers to increase venous return and reduce venous hypertension. compression stockings are used to prevent venous leg ulcers occurring where there is venous insufficiency, or to reduce the risk of deep vein thrombosis following surgery or immobility.

compression fracture usually of lumbar or dorsal region due to hyperflexion of spine; the anterior vertebral bodies are crushed together.

compressive force a force applied along the length of a structure, causing the tissues to approximate one another. This force can be caused by muscular activity, weight bearing, gravity or external loading down the length of the bone. It is necessary for the development and growth of bone. If a large compressive force, which surpasses the stress limits of the structure, is applied, a fracture will occur.

Compton scattering takes place when an X-ray photon collides with an electron and in doing so gives up some of its energy to the electron resulting in a decrease in the unit mass and an increase in the photon energy.

compulsive action performed by an individual at the supposed instigation of another’s dominant will, but against his own. impulsive action resulting from a sudden urge rather than the will.

computed radiography the use of digital imaging in imaging departments. See also digital imaging.

computed tomography (CT) computer-constructed imaging technique of a thin slice through the body, derived from X-ray absorption data collected during a circular scanning motion. Also known as computed axial tomography.

computer algorithms instructions within computer programs which translate the raw data into a usable form.

concentric having a common centre or point.

concentric muscle work the shortening of a muscle to pull its attachments closer together and produce movement at a joint. For example, the quadriceps muscles of the anterior thigh work concentrically to straighten the knee.

conchae three bony projections that lie in the nasal cavity.

concomitant several things occurring simultaneously such as chemotherapy and radiotherapy.

concretion a deposit of hard material; a calculus.

concussion a condition resulting from a blow to the head or the brain being shaken, characterized by headache, amnesia, memory loss and visual symptoms.

condensation the process of becoming more compact, for example, the changing of a gas to a liquid.

conditioned reflex a reaction acquired by practice or repetition.

conduction the transmission of heat, light, or sound waves through suitable media; also the passage of electrical currents and nerve impulses through body tissues.

conduction band an area containing electrons which are free of the nucleus of the atom and are therefore free to move around. They therefore take part in electrical conduction through the material.

conductive deafness deafness due to interruption of the conduction of sound waves from the atmosphere to the inner ear.

conductor a substance or medium which transmits heat, light, sound, electric current, etc. Material that allows the free flow of electrons. The degree of conductivity varies, some substances being good conductors, whereas others are non-conductors.

condylar joint a synovial joint that allows flexion, extension and rotation, for example, the knee joint.

condyle a rounded projection situated at the end of some bones, for example, tibia.

condyloma a wart-like growth on the anus, vulva or glans penis, usually sexually transmitted.

cone equipment slotted into the base of a light beam diaphragm to further collimate the emergent beam of radiation.

cones photoreceptors in the retina, responsible for high-definition colour vision in good light. See also rods.

confidence interval in statistics, a level, for example, 95%, that indicates the level of confidence that the test result, such as a mean, will occur within a specified range.

confidentiality a legal and professional requirement to protect all confidential information concerning patients/clients obtained in the course of professional practice, and make disclosures only with consent, where required by specific legislation, or a court order, or where disclosure in the wider public interest is justified.

conformal therapy radiotherapy techniques that try to ensure that the dosage given to the treatment area matches exactly the size and shape of the tumour while minimizing the dosage to healthy tissue. Employs the use of a multi-leaf collimator.

confounding factors extraneous factors, apart from the variables already allowed for, that distort research findings.

confounding variable one that affects the conditions of the independent variables unequally.

congenital of abnormal conditions, present at birth, often genetically determined. Existing before or at birth, usually associated with a defect or disease, for example, developmental dysplasia of the hip (DDH) (previously known as congenital dislocation of the hip).

congenital deafness present at birth, for example, caused by maternal rubella in early pregnancy. sensorineural (perceptive) or nerve deafness is due to a lesion in the inner ear, the auditory nerve or the auditory centres in the brain. See also hearing impairment.

congenital heart disease developmental abnormalities in the anatomy of the heart, resulting postnatally in imperfect circulation of blood and often manifested by murmurs, cyanosis, breathlessness and sweating. See also ‘blue baby’.

congestion hyperaemia. Passive congestion results from obstruction or slowing down of venous return, as in the lower limbs or the lungs.

congestive heart (cardiac) failure a chronic inability of the heart to maintain an adequate output of blood from one or both ventricles, resulting in pulmonary congestion and overdistension of certain veins and organs with blood, and in an inadequate blood supply to the body tissues.

congruent when describing a visual field defect implies the defect affects the same area of the field in both eyes.

conization the removal of a cone-shaped sample of tissue.

conjugate a measurement of the bony pelvis. diagonal conjugate the clinical measurement taken in pelvic assessment, from the lower border of the symphysis pubis to the sacral promontory = 111–126mm. It is 18.5mm greater than obstetrical conjugate, the available space for the fetal head, i.e. the distance from the sacral promontory to the posterior surface of the top of the symphysis pubis = 108–114mm. true conjugate the distance from the sacral promontory to the summit of the symphysis pubis = 110.5mm.

conjunctiva the delicate transparent membrane which lines the inner surface of the eyelids (palpebral conjunctiva) and reflects over the eyeball (bulbar or ocular conjunctiva).

conjunctivitis inflammation of the conjunctiva. Usually infective or allergic. Follicular and papillary types may indicate cause.

connective tissue the diverse group of tissue that includes adipose, areolar, bone, cartilage, blood and blood-producing tissue, elastic, fibrous and reticular.

connective tissue massage manipulations that stretch the superficial and deep connective tissue in order to stimulate the circulation.

Conradi–Hönermann syndrome a skeletal dysplasia which is inherited as an autosomal dominant trait. Skeletal abnormalities are variable; they are present at birth. After the first few weeks, life expectancy is normal.

conscientious objection a legal recognition that an individual is not bound to take part in some specific activities such as termination of pregnancy. It may also apply to other strongly held beliefs that are not acknowledged by law.

consciousness a complex concept which implies that a person is consciously perceiving the environment through the five sensory organs, and responding to the perceptions. See also anaesthesia.

consent patients are legally required to consent to treatment, surgery and any intervention that requires physical contact. Consent may be verbal, written, or implied, i.e. by non-verbal communication. However, where there are likely to be risks or disputes, written consent is advisable. It is the responsibility of the healthcare professional undertaking the procedure to provide a full explanation to the patient prior to treatment or surgery about what is involved and any additional measures that may be required and to obtain written consent. Previously this was the doctor concerned, but increasingly other healthcare professionals are undertaking treatments, for example, endoscopy by nurses. If the patient is a minor, or incapable of giving informed consent, the next-of-kin must sign the consent form.

consent form a form signed prior to an invasive procedure to indicate that permission has been given for the procedure to take place.

conservative dentistry the diagnosis, treatment and restoration of diseased or injured teeth.

conservative treatment aims at preventing a condition from becoming worse without using radical measures. For example, the use of drug therapy rather than surgery.

consolidation becoming solid, as, for instance, the state of the lung due to exudation and organization in lobar pneumonia.

constant potential (CP) a constant voltage produced by smoothing a fully rectified voltage by using capacitors.

constipation an implied chronic condition of infrequent and often difficult evacuation of faeces due to insufficient high-fibre food or fluid intake, immobility, or to sluggish or disordered action of the bowel musculature or nerve supply, or to habitual failure to empty the rectum. Other causes include pain on defecation, inability to respond to the urge to defecate, hypokalaemia, drugs such as iron preparations, pregnancy (hormonal), depression, colorectal cancer (alternating with diarrhoea) and some systemic diseases. acute constipation signifies obstruction or paralysis of the gut of sudden onset.

constituents of developer developing agents, preservative, accelerator, restrainer, buffer, sequestering agent, solvent, hardening agent, wetting agent, anti-frothing agent, fungicide.

constituents of fixer fixing agent, acid, buffer, preservative, hardener and solvent.

contact direct or indirect exposure to infection. A person who has been so exposed.

contact lens glass or plastic lens, worn under the eyelids in direct contact with conjunctiva (in place of spectacles) for therapeutic or cosmetic purposes.

contagious capable of transmitting infection or of being transmitted.

containment isolation the separation of a patient with any sort of infection to prevent the spread of infection to others. See also protective isolation, source isolation.

contiguous touching, close. In CT scanning refers to slice reconstruction with no interslice spacing.

contingency fund an amount of money included in the costings of a project that would be used for some unplanned or unpredictable expense.

continuity equation used in ultrasound to assess the area of a heart valve using measurements of the velocity and mean pressure gradient of the blood flow through the valve and the width of the valve.

continuous ambulatory peritoneal dialysis (CAPD) peritoneal dialysis carried out every day, by patients needing renal replacement therapy, at home.

continuous passive motion (CPM) form of passive mobilization, used to help the recovery of cartilage after knee surgery.

continuous positive airways pressure (CPAP) the application of gas at a constant positive pressure, to the airway of a spontaneously breathing patient, via an endotracheal tube or tightly fitting face mask. It reduces alveolar collapse at the end of expiration and reduces the work of breathing; used at night in patients with sleep apnoea.

continuous subcutaneous insulin infusion (CSII) the use of a pump to deliver insulin continuously, either with a fixed or variable basal rate, and with a facility for bolus dosing, to achieve almost physiological control of diabetes mellitus.

continuous wave Doppler when a fixed frequency ultrasound is transmitted continuously by one crystal and is received continuously by an adjacent crystal. Any motion within the beam will produce a measurable Doppler shift. It can measure very high flow velocities but has no range resolution.

continuous wave probe (CW probe) used in a Doppler scan where one half of the transducer head emits a continuous ultrasound beam and the other half continuously receives the reflected beam, for example, a pencil probe. See also Doppler effect, Doppler scanner.

contouring device an aid to radiotherapy planning. The device accurately records the patient outline to facilitate accurate dose distributions to be planned. See also lead strip, adjustable template, rotation jig.

contraceptive an agent used to prevent conception, for example, condom, spermicidal vaginal pessary or cream, rubber cervical cap, intrauterine device. See also combined oral contraceptive, intrauterine device.

contract draw together; shorten; decrease in size. Acquire by contagion or infection.

contracted pelvis one in which one or more diameters are smaller than normal; this may result in difficulties in childbirth.

contractile having the ability to shorten – usually following stimulation. A property of muscle tissue.

contraction shortening, for example, in muscle fibres.

contracture shortening of scar or muscle tissue, causing deformity. See also Dupuytren’s contracture.

contraindication any factor or condition indicating that a certain type of treatment (usually used for that condition) should be discontinued or not used.

contralateral on the opposite side.

contrast the difference in density between two adjacent areas on a film, the higher the contrast the more black and white the film, the lower the contrast the more shades of grey. See also gamma, subject contrast, film contrast, radiographic contrast, subjective contrast.

contrast agent either positive substances (non-ionic iodine compounds or barium) or negative substances (air, water or carbon dioxide) which can be used to demonstrate organs, vessels or parts of the body more clearly during imaging investigations by changing the subject density.

contrecoup injury or damage at a point opposite the impact, resulting from transmitted force. It can occur in an organ or part containing fluid, as the skull.

control group in research, the group that is not exposed to the independent variable, such as a therapeutic intervention or experimental drug. See also experimental group, variable.

controlled area an area where the dose rate exceeds a specific dose rate or an employee is likely to receive more than three tenths the relevant dose limit. Access is restricted to specific staff members and patients undergoing therapeutic or diagnostic procedures.

controlled-dose transdermal absorption of drugs application of a drug patch to the skin: gradual absorption gives a constant level in the blood. Examples include hormone replacement, and nicotine for smoking cessation.

controlled drugs preparations subject to regulatory control and include psychoactive drugs including narcotics, barbiturates, cocaine, morphine, hallucinogens, depressants and stimulants.

Control of Substances Hazardous to Health (COSHH) regulations relating to obligatory risk assessment and action to be taken, such as during the use of certain anaesthetic agents.

contusion (bruise) injury by a blow, when the skin is not broken.

convection transfer of heat from the hotter to the colder part; the heated substance (gas or fluid), being less dense, tends to rise. The colder portion, flowing in to be heated, rises in its turn; thus convection currents are set in motion.

conventional fractionation radiotherapy given once daily over a predetermined period of time.

converging collimator gamma camera collimator where the piece of lead has holes which are shaped to focus the gamma rays on a single spot, the main use is in brain imaging.

conversion in an intensifying screen is when energy is released from absorbed electrons in the form of light photons. In developer, when the chemical precipitates metallic silver from the silver salts in the film during processing. In the fixer when the unexposed, undeveloped silver halides are removed from the film to make the image stable.

convoluted tubule coiled tube in the kidney cortex.

convolutions folds, twists or coils as found in the intestine, renal tubules and the surface of the brain.

convulsion uncontrolled, generalized movements which may be associated with a loss of consciousness.

Cooley’s anaemia thalassaemia.

coordination moving in harmony. The body’s ability to execute smooth, fluid, accurate and controlled movements.

copy film film used to produce exact copies of radiographs by direct contact printing.

coracobrachialis muscle a muscle of the upper arm.

cord a thread-like structure. See also spermatic cord, spinal cord, umbilical cord, vocal cord.

cordectomy surgical excision of a cord, usually reserved for a vocal cord.

cordotomy (chordotomy) division of the anterolateral nerves in the spinal cord to relieve intractable pain in the pelvis or lower limbs.

core central portion, usually applied to the slough in the centre of a boil.

core body temperature that in the organs of the central cavities of the body (cranium, thorax and abdomen).

cornea the outwardly convex transparent membrane forming part of the anterior outer coat of the eye. It is situated in front of the iris and pupil and merges backwards into the sclera.

corneal reflex a reaction of blinking when the cornea is touched.

corneoscleral associated with the cornea and sclera, as the circular junction of these structures.

coronal in dentistry relating to a crown.

coronal discharge when electrons are forcibly removed from their orbits to create an electric spark.

coronal plane an imaginary plane passing through the midline of the body dividing it into front and back halves. See also frontal plane.

coronary crown-like; encircling, as of a vessel or nerve.

coronary arteries those supplying the myocardium, the first pair to be given off by the aorta as it leaves the left ventricle. Spasm, narrowing or blockage of these vessels causes angina pectoris or myocardial infarction (heart attack). Diseased vessels may be cleared by balloon angioplasty, lasers or replaced with veins taken from the legs. See also angioplasty.

coronary care unit (CCU) high dependency area in a hospital specialized in the care of patients with heart problems, particularly after a heart attack.

coronary heart disease (CHD) also known as ischaemic heart disease. It includes angina pectoris and myocardial infarction. A deficient supply of oxygenated blood to the myocardium, causing central chest pain of varying intensity that may radiate to arms and jaws. The lumen of the blood vessels is usually narrowed by atheromatous plaques. If treatment with drug therapy is unsuccessful, percutaneous transluminal angioplasty, or surgery, may be considered. See also angina pectoris, angioplasty, myocardial infarction.

coronary sinus channel receiving most venous blood from the myocardium and opening into the right atrium.

coronary thrombosis occlusion of a coronary vessel by a thrombus. The area deprived of blood becomes necrotic and is called an infarct. See also ischaemic heart disease, myocardial infarction.

coronaviruses a group of RNA viruses responsible for acute respiratory infections such as the common cold.

coroner in England and Wales, an officer of the Crown, usually a solicitor, barrister or doctor, who presides over the Coroner’s Court responsible for establishing the cause of death in cases where violence may be a possibility or suspected. Where doubts exist about the cause of death the doctor should consult the coroner and act on his or her advice. The coroner must be notified if a patient dies within 24 hours of admission to hospital. In addition all theatre/anaesthetic deaths must also be reported. Any death where the deceased has not been seen by a doctor recently requires that a coroner’s postmortem is undertaken. In Scotland, reports about such deaths are submitted to the Procurator Fiscal but a postmortem is normally only ordered if foul play is suspected. The Scottish equivalent of the Coroner’s Inquest is the Fatal Accident Enquiry, presided over by the Sheriff.

cor pulmonale heart disease resulting from disease of the lung (emphysema, silicosis, etc.) which strains the right ventricle.

corpus any mass of tissue which is easily distinguishable from its surroundings.

corpus callosum white matter joining the two cerebral hemispheres.

corpus luteum a yellow mass which forms in the ovary after ovulation. It secretes progesterone and persists to maintain pregnancy should it occur.

corpuscle outdated term for blood cells. See also erythrocytes, leucocytes.

correlation in statistics, associated with. See also positive correlation, negative correlation.

correlation coefficient (r) a value between +1 (perfect positive correlation) and −1 (perfect negative correlation). 0 equals no linear relationship.

cortex the outer layer of an organ or structure beneath its capsule or membrane such as the cerebral cortex or renal cortex.

corticosteroids hormones produced by the adrenal cortex. The word is also used for synthetic steroids such as prednisolone and dexamethasone.

cortisol hydrocortisone, one of the principal adrenal cortical steroids. It is essential to life. There is decreased secretion in Addison’s disease and increased amounts in Cushing’s disease and syndrome.

cortisone one of the hormones of the adrenal gland. It is converted into cortisol before use by the body. Used therapeutically as replacement in conditions that include Addison’s disease. cortisone suppression test differentiates primary from secondary hypercalcaemia.

cosmesis the use of cosmetics or surgery for preserving or enhancing self-image.

cosmetic dentistry the restoration or enhancement of dental aesthetics.

costal associated with the ribs.

costal cartilages those cartilages which attach the ribs to the sternum and each other.

cost–benefit analysis (CBA) method of analysis used in the economic evaluation of healthcare interventions (programmes or procedures). Health outcomes are measured in monetary terms to enable comparisons between interventions from a variety of disciplines. There are problems with valuing life and health in monetary terms. So this method is not widely used.

cost centre a department, for example physiotherapy or catering, for which a budget covering staff and other resources has been set.

cost effectiveness analytical technique used in the economic evaluation of healthcare interventions (programmes and procedures). A cost-effectiveness analysis is used when the outcomes of the procedures are not necessarily the same, but can be measured in the same natural units. For example, the outcomes may be measured in death rates, healthy years of life gained, symptom-free days, or even blood pressures. The output of this type of analysis is ‘cost per unit increase’. For example, cost of intervention against cost per life year gained. Health benefits are measured in natural units (for example, mortality rates, survival rates) or final clinical outcomes (for example, cost per life years gained, cost per days off sick reduced). Intermediate clinical outcomes are sometimes used (for example, number of cancers detected in a screening programme) but this is not valid if a clear association between cancer detected and survival or quality of life cannot be demonstrated.

cost minimization analytic technique used in economic evaluation of healthcare interventions (programmes or procedures). A cost-minimization analysis is used when the outcomes or consequences of the procedures are the same. A prerequisite for such a study is that there is evidence (preferably from a randomized clinical trial) that the different procedures are equally effective. A cost minimization analysis therefore solely consists of the analyses of costs. Common examples include comparisons of home and hospital care for chronic and terminal conditions.

costochondral associated with a rib and its cartilage.

costochondritis inflammation of the costochondral cartilage.

costoclavicular associated with the ribs and the clavicle.

costoclavicular syndrome is a synonym for cervical rib syndrome.

cost utility analytic technique used in economic evaluation of healthcare interventions (programmes or procedures). A cost-utility analysis is used when the outcomes cannot be measured in natural units, so a utility or value scale has to be employed. This may be because the important outcomes of the procedures are not directly comparable or they are multi-faceted, for example, a comparison of amputation against waiting for the treatment of a gangrenous foot – outcomes could be pain, mobility and/or survival. The commonly used utility scale is quality-adjusted life years (QALYs), which use survey tools such as the Nottingham Health Profile to allocate ‘relative qualities’ to different health states. However, different people value their health differently; therefore utility ratings are not unique. Research has provided ‘average’ utility. Cost utility analyses report results as ‘costs per QALY (gained)’.

cot death see sudden infant death syndrome.

cotyledon one of the subdivisions of the uterine surface of the placenta.

cough explosive expulsion of air from the lungs. It may be volun-tary, or as protective reflex that expels a foreign body such as food or sputum. Cough may be a feature of numerous respiratory and cardiac conditions.

coulomb is equal to the charge carried by 6 ÷ 10¹⁸ electrons or protons.

countertraction traction upon the proximal extremity of a fractured limb opposing the pull of the traction apparatus on the distal extremity.

count rate the number of gamma ray detections made by a gamma camera per minute.

coupling gel a gel put on a patient’s skin during an ultrasound examination to exclude any air between the transducer and the skin surface to enable the transmission of ultrasound waves between the transducer and the patient.

covalent bond is when two atoms share electrons in such a way that each atom appears to share the number of electrons in an apparent closed shell.

Cowper’s glands see bulbourethral (Cowper’s) glands.

coxa the hip joint.

coxa valga an increase in the normal angle between neck and shaft of femur.

coxa vara a decrease in the normal angle plus torsion of the neck, for example, slipped femoral epiphysis.

coxalgia pain in the hip joint.

coxitis inflammation of the hip joint.

CP/M one of the most common ‘universal’ computer languages.

CPS (Characters Per Second) a measure of the speed of data output.

CPU (Central Processing Unit) the core of the computer.

cranial associated with the cranium, towards the head.

cranial cavity the brain box formed by the bones of the cranium.

craniofacia associated with the cranium and the face.

craniometry the science which deals with the measurement of skulls.

craniopharyngioma a congenital, benign tumour which develops between the brain and the pituitary gland.

cranioplasty operative repair of a skull defect.

craniosacral associated with the skull and sacrum. Applied to the outflow of the parasympathetic nervous system.

craniostenosis a condition in which the skull sutures fuse too early and the fontanelles close. It may cause increased intracranial pressure requiring surgery.

craniosynostosis premature fusion of cranial sutures resulting in abnormal skull shape and craniostenosis. Deformities depend on which sutures are affected.

craniotabes a thinning or wasting of the cranial bones occurring in infancy and usually due to rickets.

craniotomy a surgical opening of the skull in order to remove a growth, relieve pressure, evacuate blood clot or arrest haemorrhage.

cranium the part of the skull enclosing the brain. It is composed of eight bones: the occipital, two parietals, frontal, two temporals, sphenoid and ethmoid.

creatine a nitrogenous compound produced in the body.

creatine kinase (ATP: creatine phosphotransferase) occurs as three isoenzymes. It is found in brain tissue, skeletal muscle, blood and in myocardial tissue.

creatine kinase test increased levels of the myocardial isoenzyme in serum is indicative of acute myocardial infarction. phosphorylated creatine the important storage form of high-energy phosphate.

creatinine a waste product of protein (endogenous) and nucleic acid metabolism found in muscle and blood and excreted in normal urine. serum creatinine is raised in hyperthyroidism, muscle wasting disorders and in renal failure.

crepitus (crepitation) grinding noise or sensation within a joint, as in osteoarthritis. A feature of fracture in overuse injury. Crackling sound heard via stethoscope. Crackling sound elicited by pressure on tissue containing air (surgical emphysema).

crest a sharp ridge of bone.

cretinism obsolete term. See also hypothyroidism.

Creutzfeldt–Jakob disease (CJD) a progressive dementia transmissible through prion protein. new variant CJD mainly affecting young adults, is possibly linked with the prion causing bovine spongiform encephalopathy (BSE). CJD follows a rapid degenerative course often with spasmodic contraction of the muscles (myoclonus) and is usually fatal.

cribriform perforated, like a sieve.

cribriform plate that portion of the ethmoid bone allowing passage of fibres of olfactory nerve.

cricoid ring-shaped. Applied to the cartilage forming the inferior posterior part of larynx.

cricoid pressure a practical manoeuvre in which manual pressure is applied over the cricoid cartilage to occlude the oesophagus to prevent regurgitation and aspiration of gastric contents during induction of anaesthesia.

cricothyroidotomy (cricothyrotomy) incision through the skin and cricothyroid membrane to secure a patent airway for emergency relief of upper airway obstruction. See also tracheostomy.

criminal law the law that creates offences heard in the criminal courts such as theft.

criminal wrong an act or omission that can be pursued in the criminal courts.

critical angle when an incident beam of ultrasound strikes an interface at an angle equal to or greater than this angle, only reflection of the beam will occur.

critical appraisal the process of making an objective judgement regarding a research study. Includes research design, methodology, analysis, interpretation of results and the applicability of the study findings to a particular area of health care.

Crohn’s disease a chronic recurrent granulomatous inflammation affecting any part of the bowel from mouth to anus. Inflammation may be discontinuous (‘skip lesions’) with normal bowel in between. May be complicated by fistulae and strictures. See also inflammatory bowel disease.

Crosby capsule a special tube which is passed through the mouth to the small intestine. Allows biopsy of jejunal mucosa. Endoscopic biopsy is often used in preference to this time-consuming investigation.

cross infection infection that a person receives from another person.

crossover effect the amount of light transmitted to the opposite side of a film base expressed as a percentage.

crossover studies a research study where the participants are exposed to both the experimental intervention and the placebo one after another.

croup viral infection leading to laryngeal narrowing. The child has ‘croupy’, stridulous (noisy or harsh-sounding) breathing. Narrowing of the airway which gives rise to the typical attack with crowing inspiration may be the result of oedema or spasm, or both.

crown the top part of a structure. artificial crown in dentistry, restoration used to cover the part of the tooth that projects above the gum line, usually made of metal, porcelain, or a combination of both. crown of a tooth that part of the tooth covered with enamel.

crown–rump length a measurement, used in ultrasound imaging, of the length of the fetal head and body between the 6th and 14th week of pregnancy to assess the age of the fetus.

CRS (NHS Care Record Service) provides computerized patient records and will be linked with PACS to provide full clinical information on patients.

cruciate shaped like a cross such as the ligaments stabilizing the knee joint.

crus a structure which is leg-like or root-like. Applied to various parts of the body, for example, crus of the diaphragm.

crutch palsy paralysis of extensor muscles of wrist, fingers and thumb from repeated pressure of a crutch upon the radial nerve in the axilla.

cryoanalgesia the relief of pain symptoms by blocking peripheral nerve conduction with extreme cold.

cryogenic produced by low temperature. Also used to describe any means or apparatus involved in the production of low temperature.

cryoprobe freezing probe which can be used to destroy tumours.

crystal defects imperfections within a crystal which create areas of low energy called ‘electron traps’ and ‘holes’. See also point defects, line defects.

cryosurgery the use of intense, controlled cold to remove or destroy diseased tissue without harming the adjacent tissue.

cryotherapy a method of freezing a tumour, the use of cold for the treatment of disease.

cryptogenic of unknown or obscure cause.

cryptogenic fibrosing alveolitis interstitial lung disease characterized by cellular infiltration and thickening of the alveolar walls. Pulmonary macrophages are implicated in fibrosis, and in recruiting other cell types such as neutrophils to the lung.

cryptorchism a developmental defect whereby the testes do not descend into the scrotum; they are retained within the abdomen or inguinal canal.

crystalluria excretion of crystals in the urine.

crystal violet (gentian violet) a brilliant, violet-coloured, antiseptic aniline dye, used as 0.5% solution as a stain. It is only licensed for application to intact skin, the exception being marking the skin before surgery.

CT number the number given to a pixel in a digital image to denote the calculated attenuation at that point of the image, expressed in Hounsfield Units.

CT scanner computed tomography equipment now most commonly used to produce a volume of data which can provide multi planar sectional images of the patient using a beam of radiation that rotates continuously around the patient as they move through the path of the beam. The image is produced by a computer which measures the attenuation of radiation in the body and reconstructs images on a monitor.

CT simulator equipment for very accurate treatment planning prior to radiotherapy comprising of a CT scanner, laser positioning aids and a virtual simulation treatment planning computer.

cubital tunnel external compression syndrome ulnar paralysis resulting from compression of the ulnar nerve within the cubital tunnel situated on the inner and posterior aspect of the elbow – sometimes referred to as the ‘funny bone’.

cubital vein situated in the arm.

cubitus the forearm; elbow.

cuboid shaped like a cube. One of the bones of the foot.

culdoscope an endoscope used via the vaginal route.

culdoscopy a form of peritoneoscopy or laparoscopy. Passage of a culdoscope through the posterior vaginal fornix, behind the uterus to enter the peritoneal cavity, for viewing same.

culture the growth of microorganisms on artificial media under ideal conditions.

cumulative activity total quantity of radiation produced over a period of time.

Cumulative Index to Nursing and Allied Health Literature (CINAHL) computerized database of literature relevant to nursing and allied health.

cuneiform bones three wedge-shaped bones in the foot, the medial, inter-mediate and lateral cuneiform bones.

curettage the scraping of unhealthy tissue from a cavity. This may be treatment or may be done to establish a diagnosis after laboratory analysis of the scrapings.

curette a spoon-shaped instrument or a metal loop which may have sharp and/or blunt edges for scraping out (curetting) cavities.

curie (Ci) a measure of radioactivity, equal to 3.7 ÷ 10¹⁰ nuclear disintegrations per second, now replaced by the Becquerel.

Curling’s ulcer acute peptic ulceration which occurs either in the stomach or duodenum as a response to the physiological stress of extensive burns or scalds.

cursor a flashing marker on the computer screen which indicates where the next character is to be inserted.

curved array in ultrasound, a set of elements mounted in a curved line to give a wide field of view, for example, obstetric scans.

Cushing’s disease a rare disorder, mainly of females, characterized principally by a cushingoid appearance, proximal myopathy, hyperglycaemia, hypertension and osteoporosis; due to excessive cortisol production by hyperplastic adrenal glands as a result of increased adrenocorticotrophin (ACTH) secretion by a tumour or hyperplasia of the anterior pituitary gland.

Cushing’s reflex a rise in blood pressure and a fall in pulse rate; occurs in cerebral space-occupying lesions.

Cushing’s syndrome clinically similar to Cushing’s disease but including all causes: (a) adrenocortical hyperplasia, adenoma or carcinoma, which can be associated with excessive body hair and low levels of potassium due to excess of other adrenal steroids; (b) ectopic ACTH secretion by tumours, for example, small cell lung cancer, often associated with darkening of the skin; (c) iatrogenic due to treatment with glucocorticoids.

cusp a projecting point, such as the edge of a tooth or the segment of a heart valve. The cardiac tricuspid valve has three, the mitral (bicuspid) valve two cusps.

cuticle the epidermis or dead epidermis, as that which surrounds a nail.

cut-off sensitivity the electromagnetic wavelength that a film emulsion is no longer sensitive to.

cyanosis a bluish tinge to the skin due to a lack of oxygen, observed most frequently under the nails, lips and skin.

cycle one complete waveform in alternating current, usually measured from zero to zero or from peak to peak.

cyclical vomiting periodic attacks of vomiting in children, usually associated with ketosis and usually with no demonstrable pathological cause. Occurs mainly in highly strung children.

cyclotron a device to accelerate charged particles or ions which then bombard a target in which nuclear reactions result in the production of radionuclides. These can then be used as a source of neutrons or protons for therapeutic radiopharmaceuticals.

cylindroma a tumour of the endothelial element of apocrine tissue such as a sweat gland or a salivary gland. The supporting stroma is hyalinized.

cyst a closed cavity or sac usually with an epithelial lining, enclosing fluid or semisolid matter.

cystadenoma an innocent cystic new growth of glandular tissue. Liable to occur in the female breast.

cystectomy usually refers to the removal of part or the whole of the urinary bladder. This necessitates urinary diversion.

cystic fibrosis (fibrocystic disease of the pancreas, mucoviscidosis) the commonest genetically determined disease in Caucasian populations; there is abnormality of secretion of the exocrine glands. Thick mucus can block the intestinal glands and cause meconium ileus in a baby; later it can cause steatorrhoea and malabsorption. Thick mucus in the respiratory glands predisposes to repeated infections and bronchiectasis. Abnormality of the sweat glands increases the chloride content of sweat, which is a diagnostic tool.

cystinosis a recessively inherited metabolic disorder in which crystalline cystine is deposited in the body. Cystine and other amino acids are excreted in the urine.

cystinuria metabolic disorder in which cystine and other amino acids appear in the urine. A cause of renal stones.

cystitis inflammation of the urinary bladder; the cause is usually bacterial. The condition may be acute or chronic, primary or secondary to stones, etc. More frequent in females, as the urethra is short.

cystocele prolapse of the posterior wall of the urinary bladder into the anterior vaginal wall. See also colporrhaphy.

cystodiathermy the application of a cauterizing electrical current to the walls of the urinary bladder through a cystoscope, or by open operation.

cystography the radiographic examination of the urinary bladder following the introduction of a catheter via the urethra for the introduction of contrast agent.

cystolithiasis the presence of a stone or stones in the urinary bladder.

cystometer an apparatus for measuring the pressure under various conditions in the urinary bladder.

cystometrogram a record of the changes in pressure within the urinary bladder under various conditions; used in the study of voiding disorders.

cystometry the study of pressure changes within the urinary bladder.

cystoplasty surgical repair or augmentation of the urinary bladder.

cystoprostourethrectomy the surgical removal of the bladder and prostate with diversion of the ureters onto the abdominal wall.

cystoscope an endoscope used to visualize the inner aspect of the bladder.

cystoscopy use of a cystoscope to view the internal surface of the urinary bladder.

cystostomy (vesicostomy) an operation whereby a fistulous opening is made into the urinary bladder via the abdominal wall. Usually the fistula can be allowed to heal when it is no longer needed.

cystotomy incision into the urinary bladder via the abdominal wall.

cystourethritis inflammation of the urinary bladder and urethra.

cystourethrogram radiographic examination of the urinary bladder and urethra. See also micturating cystourethrogram.

cystourethroscopy the examination of the urethra and urinary bladder under general anaesthetic using a cystoscope.

cytochrome a series of proteins containing iron or copper. They have a similar structure to haemoglobin and are involved in mitochondrial oxidation–reduction reactions (electron transport chain) that produce ATP.

cytochrome P₄₅₀ liver enzyme important in the oxidation and clearance of lipid-soluble drugs.

cytodiagnosis diagnosis by the microscopic study of cells.

cytogenetics the scientific study of cells; particularly of chromosomes, genes and their behaviour. Chromosomes can be studied by culture techniques, using either tissue such as skin or lymphocytes, or fetal cells obtained by chorionic villus sampling or amniocentesis.

cytokines proteins which act either on the cytokine-producing cell, or on other cells, via cell-surface receptors. The term is usually applied to proteins which act on immune cells (T cells, B cells, monocytes, etc.). Cytokines have many diverse effects on many different types of cell. Examples include interleukins (for example, IL-1, IL-2), tumour necrosis factor, interferon-alpha and interferon-gamma.

cytology the study of isolated cells or those in tiny clusters.

cytoplasm (protoplasm) the complex chemical compound constituting the main part of the living substance of the cell, other than the contents of the nucleus.

cytoreduction the reduction of the size of a tumour using hormone or cytotoxic drugs.

cytotoxic any substance which kills or inhibits the growth of cells.

cytotoxic drugs drugs used mainly for the treatment of malignant diseases, but sometimes for other conditions. They work in different ways, but they all eventually cause cancer cell death by either disrupting DNA or causing programmed cell death. Some are cell cycle phase specific and others work at any point in the cell cycle. They also harm some normal cells and some have longer-term side-effects. There are five groups: (a) alkylating agents that disrupt DNA, for example, busulfan, cyclophosphamide; (b) antimetabolites that disrupt DNA by blocking enzymes required for its synthesis, for example, 5-fluorouracil; (c) antitumour antibiotics that disrupt DNA and the cell membrane, for example, bleomycin; (d) vinca alkaloids and other plant extracts that disrupt microtubules during cell division, for example, vincristine; (e) miscellaneous group that work in a variety of ways, for example, asparaginase. See also chemotherapy.

cytotoxins antibodies which are toxic to cells.

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