F
fabella a sesamoid bone sometimes found posterior to the knee joint.
facet a small, smooth, flat surface of a bone or a calculus.
facial associated with the face.
facial hemiatrophy a congenital condition, or a manifestation of scleroderma in which the structures on one side of the face are shrunken.
facial nerve seventh pair of cranial nerves. They supply the facial muscles, the salivary, lacrimal and nasal glands, and part of the tongue.
facial paralysis paralysis of muscles supplied by the facial nerve.
facies the appearance or the expression of the face. adenoid facies open mouthed, vacant expression due to deafness from enlarged pharyngeal tonsils (adenoids). Parkinson facies a mask-like appearance; saliva may trickle from the corners of the mouth.
facilitated diffusion process whereby larger non-fat-soluble molecules such as glucose pass into the cell by using a protein carrier molecule. No energy is required but there must be a concentration gradient.
faecalith a concretion formed in the bowel from faecal matter: it can cause obstruction and/or inflammation.
faecal softeners see laxatives.
faeces the waste material eliminated from the bowel, consisting mainly of indigestible cellulose, unabsorbed food, intestinal secretions, water, electrolytes and bacteria, etc.
failure to thrive failure to develop and grow at the expected rate, ascertained by consistent measurement of height and weight plotted on a growth chart. It may result from an organic disorder or have non-organic causes, such as poor feeding, maternal deprivation or psychosocial problems. Careful investigation is required to establish the cause.
faint a temporary loss of consciousness. See also syncope.
fallopian tubes see uterine tubes.
Fallot’s tetralogy a cyanotic congenital heart defect comprising a ventricular septal defect, narrowing of the right ventricular outflow tract (subvalvular pulmonary stenosis), right ventricular hypertrophy and malposition of the aorta overriding the ventricular septum. Amenable to corrective surgery.
false pelvis the wide expanded part of the pelvis above the brim.
falx a sickle-shaped structure.
falx cerebri that portion of the dura mater separating the two cerebral hemispheres.
familial adenomatous polyposis a dominantly inherited condition in which multiple polyps occur throughout the large bowel and which invariably leads to colon cancer. Polyps also occur in the stomach and duodenum.
Family Health Services (FHS) community-based services provided by family doctors, dentists, opticians and pharmacists as independent contractors. They are not directly employed by the NHS, but have contractual arrangements to practise in the NHS.
farad (F) a measure of capacitance, an electrical system has a capacitance of 1 farad if a charge of 1 coulomb held by the body results in a potential of 1 volt.
Faraday’s laws of electromagnetic induction (1) a change in the magnetic flux linked with a conductor induces an electromotive force in the conductor. (2) The size of the induced electromotive force is proportional to the rate of change of the magnetic flux linkage.
farmer’s lung see extrinsic allergic alveolitis.
fascia a connective tissue sheath consisting of fibrous tissue and fat which unites the skin to the underlying tissues. It also surrounds and separates many of the muscles, and, in some cases, holds them together.
fasciculus a little bundle, as of muscle or nerve.
fasciitis an abnormal benign growth which develops in the subcutaneous oral tissue, usually in the cheek. Inflammation of the connective tissue.
Fatal Accident Enquiry see coroner.
fatigue weariness. Physiological term for diminishing muscle reaction to stimulus applied. In sports medicine the failure of muscle(s) to maintain force (or power output) during sustained or repeated contractions.
fatigue fracture see stress fracture.
fatigue index (FI) the decline in power divided by the time (in seconds) interval between maximum (peak) and minimum power, recorded during an anaerobic power exercise test.
fatty acid hydrocarbon component of lipids. May be unsaturated (monounsaturated or polyunsaturated) or saturated depending on the number of double chemical bonds in their structure.
fatty degeneration tissue degeneration that leads to the appearance of fatty droplets in the cytoplasm; found especially in disease of heart, liver and kidney.
fatty liver accumulation of fat in the liver, an indication of diffuse liver disease or benign changes, demonstrated using grey scale ultrasound.
fat/water suppression a method that suppresses signal within the imaging volume from either fat or water protons by applying a frequency selective, saturation, radio frequency pulse in magnetic resonance imaging.
fauces the opening from the mouth into the pharynx, bounded above by the soft palate, below by the tongue. pillars of the fauces, anterior and posterior, lie laterally and surround the palatine tonsil.
febrile feverish; accompanied by fever. febrile convulsions occur in children who have an increased body temperature; they do not usually result in permanent brain damage. Most common between the ages of 6 months and 5 years. See also convulsions.
feedback a homeostatic control mechanism. It is usually negative feedback where a physiological process is slowed or ‘turned off’ by an increasing amount of product, for example, temperature control. Much more rarely in positive feedback the process is speeded up by high levels of the product, for example, normal blood clotting. feedback treatment See biofeedback.
femoral associated with the femur or thigh. Applied to the vein, artery, nerve and canal.
femoral arteriography a contrast agent is injected via a catheter in the femoral artery to demonstrate the arterial circulation of the leg.
femoral hernia protrusion through the femoral canal, alongside the femoral blood vessels as they pass into the thigh.
femoropopliteal usually, referring to the femoral and popliteal vessels.
femur the thigh bone, the longest and strongest bone in the body.
fenestra a window-like opening.
fenestra ovalis an oval opening between the middle and internal ear.
fenestra rotunda a round opening which lies below the fenestra ovalis.
fenestration a perforation, opening or pore, the glomerular capillaries of the nephron, which form part of the filtration membrane, are adapted for permeability and filtration by the presence of fenestrations. A surgical opening (or fenestra) in the inner ear to ease the deafness caused by otosclerosis.
ferritin an iron–protein complex. A storage form of iron.
ferromagnetic a substance that if placed in a magnetic field becomes magnetized and once the magnetic field is removed it retains its magnetism, for example iron, cobalt or nickel. See also diamagnetic, paramagnetic, superparamagnetic.
ferromagnetism if an external magnetic force is applied to the material all the magnetic domains align in the same direction forming a strong magnet.
fetal age viability defined as when a baby can survive outside the womb, that is, 24 weeks gestational age.
fetal alcohol syndrome (FAS) stillbirth and fetal abnormality due to prenatal growth retardation caused by excessive maternal alcohol consumption during pregnancy.
fetal circulation circulation adapted for intrauterine life. Extra shunts and vessels (ductus venosus, ductus arteriosus, foramen ovale and umbilical vein) allows blood to largely bypass the liver, gastrointestinal tract and lungs, as their functions are covered by maternal systems and the placenta.
fetus the developmental stage from the eighth week of gestation until birth.
fetus papyraceus a dead fetus, one of a twin which has become flattened and mummified.
fever (pyrexia) an elevation of body temperature above normal. Designates some infectious conditions, for example, paratyphoid fever, scarlet fever, typhoid fever, etc.
fibre a thread-like structure.
fibre distribution data interface (FDDI) in computing a system similar to a token ring which uses fibreoptic cables to inform nodes when they can write to the network. See also nodes.
fibreoptics light is transmitted through flexible glass fibres which enable the user to ‘see round corners’. The technology utilized in endoscopic equipment.
fibril a component filament of a fibre; a small fibre.
fibrillation uncoordinated quivering contraction of muscle; referring usually to myocardial muscle. See also atrial fibrillation, cardiac arrest, ventricular fibrillation.
fibrin the insoluble matrix on which a blood clot is formed. Produced from soluble fibrinogen by the action of thrombin.
fibrinogen factor I of blood coagulation. A soluble plasma protein that is converted to fibrin by the action of thrombin.
fibroadenoma a benign tumour containing fibrous and glandular tissue.
fibroblast (fibrocyte) a blast cell that forms connective tissues. Involved during growth and tissue repair.
fibrocartilage cartilage containing fibrous tissue.
fibrocaseous a soft, cheesy mass infiltrated by fibrous tissue, formed by fibroblasts.
fibrocyst a fibroma which has undergone cystic degeneration.
fibrocystic associated with a fibrocyst.
fibrocystic disease bone cysts which may be solitary or generalized. If generalized and accompanied by decalcification of bone, it is symptomatic of hyperparathyroidism.
fibrocystic disease of breast the breast feels lumpy due to the presence of cysts, usually caused by hormone imbalance.
fibrocystic disease of pancreas cystic fibrosis.
fibroid a fibromuscular benign tumour usually found in the uterus may be on a stalk (pedunculate) protruding from the uterus, in the wall of the uterus or in the endometrial cavity. The location of fibroids can be described as intramural (embedded in the wall of the uterus), subserous (protruding from the serosal surface into the peritoneal cavity), or submucous (protruding into the endometrial surface).
fibroma a benign tumour composed of fibrous tissue.
fibromatosis a gingival enlargement, believed to be hereditary, the tissue covers the surface of the adult teeth.
fibromuscular associated with fibrous and muscle tissue.
fibromyalgia a condition characterized by widespread pain and tender points. Many patients also complain of tiredness and of waking feeling unrefreshed.
fibromyoma a benign tumour consisting of fibrous and muscle tissue.
fibroplasia the production of fibrous tissue which is a normal part of healing.
fibrosarcoma a form of sarcoma. A malignant tumour arising from fibrous tissue.
fibrosis the formation of excessive fibrous tissues, for example, scar tissue, as a result of inflammation or pulmonary fibrosis caused by radiation, certain drugs and pneumoconiosis.
fibrositis a lay term that denotes non-specific soft-tissue pain.
fibrous joint (synarthroses) joints joined with fibrous tissue and have virtually no movement, for example, sutures.
fibrovascular relating to fibrous tissue which is well supplied with blood vessels.
fibula one of the longest and thinnest bones of the body, situated on the outer side of the leg and articulating at the upper end with the lateral condyle of the tibia and at the lower end with the lateral surface of the talus (astragalus) and tibia.
field defining wires metal wires attached to the light beam diaphragm, which can be adjusted to outline the exact treatment area on the subsequent radiograph produced in the simulator.
field of view the area of the scanned plane which may be included in the CT image.
field size the size and shape of the X-ray beam. The maximum field of view of a gamma camera, usually between 25 and 50 cm.
filament a thin, coiled, tungsten wire that when heated produces electrons in an X-ray tube.
filamented swab a piece of gauze with a radiopaque strip. Used in theatre for internal swabbing as it can be traced radiographically if lost.
file information stored on disk or cassette.
filiform papillae small projections ending in several minute processes; found on the tongue.
film badge a badge work by radiation workers which contains film, which when processed can be used to determine the amount of radiation received by that person.
film contrast this is defined as the average gradient of the film. See also characteristic curve.
film entry system the part of a radiographic film processor where the film enters the unit, it comprises of a pair of rollers and a microswitch which determines the length of time the film is between the rollers and can be linked to the replenisher system to ensure accurate replenishment.
film grain formed by the coarse structure of the crystals in a radiographic film forming an overall density in the emulsion.
filter a device designed to remove particles over a certain size or rays of specific wavelength while allowing others to pass through. Examples include intravenous fluid filters and optical filters.
filtrate substance that passes through the filter.
filtration the changes which occur in the X-ray beam when it passes through an object, it can reduce the amount of radiation and improve the quality of the beam by removing the low-energy photons. The process of straining through a filter under gravity, pressure or vacuum. Filtration under pressure occurs in the nephron of the kidney due to high-pressure blood in the afferent arteriole of the glomerulus.
filum any filamentous or thread-like structure.
filum terminale a strong, fine cord blending with the spinal cord above, and the periosteum of the sacral canal below.
fimbria a fringe, for example, of the uterine tubes.
fine focus the selection of a small filament to enable a small area of the anode to be bombarded with electrons and help reduce the unsharpness on the subsequent radiograph.
finger a digit. See also clubbed finger.
firewall either a programme or a dedicated computer used to protect a specific computer from external, unauthorized people accessing or changing information held on the computer.
firmware software, but stored on a chip.
fission occurs during radioactive decay when the nucleus of an atom elongates and breaks into two pieces.
fissure a split or cleft. Can be moist or dry cracks in the epidermis or mucosa. They usually develop at 90ö to the direction of the tension stress. Common sites include the anal mucosa and interdigitally for moist fissures, and the heel margins for dry fissures. palpebral fissure the opening between the eyelids.
fistula an abnormal communication between two organs for example between bowel and bladder. May occur in conditions such as Crohn’s disease, diverticulosis and cancer. See also arteriovenous fistula.
fixed costs the costs incurred regardless of the level of activity, for example, related to the buildings and land, equipment maintenance.
fixer a solution that converts and removes unexposed, undeveloped silver bromide into water-soluble silver complexes from the radiographic film during processing.
fixing agent a chemical, ammonium thiosulphate, that converts unex-posed, undeveloped silver bromide into water-soluble silver complexes that can be removed from the radiographic film by the solvent in the fixer solution.
flagellum a fine, hair-like appendage capable of lashing movement. Characteristic of spermatozoa, certain bacteria and protozoa.
flail chest unstable thoracic cage due to fracture. See also paradoxical respiration.
flap a unit of skin and other subcutaneous tissues that maintains its own blood and nerve supply, used to repair defects in other parts of the body. Common in plastic surgery to treat burns and other injuries; skin flaps used to cover amputation stumps.
flat bone the bones have a thin layer of cancellous bone enclosed by two layers of compact bone, they either protect underlying structures, for example, in the bones of the skull or are for muscle attachment, for example, the scapula.
flat pelvis a pelvis in which the anteroposterior diameter of the brim is reduced.
flat screen monitor a form of imaging monitor using a liquid crystal display to produce the image.
flattening filter a metal filter, conical in section being thick at the centre and thinning towards the edges, used to reduce the intensity of the central beam and ensure that during radiotherapy the central 80% of the beam does not vary more than plus or minus 3% at maximum density.
flatulence excessive gas in the gastric and intestinal tract.
flatus gas in the gastrointestinal tract.
Fleming’s left hand rule the direction of force in a conductor placed in a magnetic field is at right angles to both the current and the magnetic field. This can be predicted by holding the thumb, first and second fingers of the left hand at right angles to each other, thuMb = motion, First = force and seCond = current.
Fleming’s right hand rule the direction of force in a conductor placed in a magnetic field is at right angles to both the electron flow and the magnetic field. This can be predicted by holding the thumb, first and second fingers of the right hand at right angles to each other, thuMb = motion, First = force and sEcond = electron flow.
flexible pes planus is generally an asymptomatic abnormality of the foot in children but may become a semi-rigid condition in adulthood. It has been linked with excess laxity of the joint capsule and the ligaments supporting the arch, which allows it to collapse when weight is applied.
flexion the act of bending by which the shafts of long bones forming a joint are brought towards each other.
flexor a muscle which on contraction flexes or bends a part.
flexure a bend, as in a tube-like structure, or a fold, as on the skin – it can be obliterated by extension or increased by flexion in the locomotor system. See also left colic (splenic) flexure, right colic (hepatic) flexure, sigmoid flexure.
flip angle the angle through which the magnetization vector moves relative to the longitudinal axis of the static magnetic field as a result of the application of a radio frequency pulse in magnetic resonance imaging. The variation in flip angle is used in gradient-echo imaging to obtain various tissue weighted images. A 10–30ö flip angle produces a T2 weighted image and a 90ö flip angle provides a T1 weighted image. See also T1 relaxation time, T2 relaxation time, gradient echo.
flooding a popular term to describe excessive bleeding from the uterus.
floppy baby syndrome may be due to nervous system or muscle disorder as opposed to benign hypotonia (low muscle tone).
floppy disk a flexible disk usually 3.5 inches in diameter.
floppy disk drive an electronic device that allows information to either be written on to or removed from a floppy disk using a magnetic field.
flowchart a diagrammatic representation of a computer program.
flowmeter a measuring instrument for flowing gas or liquid.
flow-related enhancement a process when the signal intensity of moving fluids can be increased compared with the signal from stationary tissue, when in-flowing, unsaturated, fully magnetized spins replace saturated spins within the imaging slice between successive radio frequency pulses in magnetic resonance imaging.
fluctuation a wave-like motion felt on digital examination of a fluidcontaining mass.
fluorescence is when a material is irradiated and emits longer wavelength radiation, when the irradiation stops the light emission stops.
fluoride an ion sometimes present in drinking water, toothpastes, tea, vegetables and sea food. It can be incorporated into the structure of bone and teeth, where it provides protection against dental caries but in gross excess it causes mottling of the teeth. As a public health preventive measure it can be added to a water supply in a strength of 1 part fluoride in a million parts of water (fluoridation).
Fluoro CT equipment allowing the acquisition and immediate display of multiple CT images per second, is used in minimally invasive microtherapy procedures.
fluoroscopy a real time radiographic examination of the human body, observed by means of an image intensifier and a television system.
fluorosis results from an excessive intake of fluoride and results in a general increase in bone density and a mottled appearance to the teeth.
flux the lines of force through a magnetic field.
focal epilepsy an epileptic attack caused by a brain tumour, encephalitis or a head injury. Also known as Jacksonian epilepsy.
focal spot the area of the anode bombarded by electrons; due to the angle of the anode the real focal spot is larger than the apparent focal spot.
focus the point at which rays meet after reflection or refraction. The area of the anode that is bombarded by electrons.
focus groups in research a method of obtaining data that involves interviewing people in small interacting groups.
focusing coils produce magnetic fields to prevent divergence of the internal electron beam and therefore leakage of radiation from the equipment.
focusing cup part of the cathode in an X-ray tube that helps direct the electrons to land on the target.
fold-over (aliasing, wrap around) an artefact that occurs in magnetic resonance imaging due to the image encoding process. It occurs when the field of view is smaller than the area being imaged.
follicle a small secreting sac. A simple tubular gland.
follicle stimulating hormone (FSH) secreted by the anterior pituitary gland; it acts on the ovaries in the female, where it develops the oocyte-containing (Graafian) follicles; and to the testes in the male, where it stimulates spermatogenesis.
follicular carcinoma a malignant tumour of the thyroid which spreads via the blood stream and metastasizes to bone and lung.
fomite any article that has been in contact with infection and is capable of transmitting same.
fontanelle a membranous space between the cranial bones. The diamond-shaped anterior fontanelle (bregma) is at the junction of the frontal and two parietal bones. It usually closes in the second year of life. The triangular posterior fontanelle (lambda) is at the junction of the occipital and two parietal bones. It closes within a few weeks of birth.
foot that portion of the lower limb below the ankle.
foot drop inability to dorsiflex foot due normally to damage of the nerve supply to the foot. Can be a complication of bedrest.
foramen a hole or opening. Generally used with reference to bones.
foramen magnum the opening in the occipital bone through which the spinal cord passes.
foramen ovale a fetal cardiac interatrial communication which normally closes at birth. A foramen in the skull for the mandibular division of the trigeminal nerve.
forbidden energy gap an area between the top energy level of the valence band and the bottom level of the conduction band, electrons can pass through the gap but cannot exist within the band.
force the application of unit force to unit mass produces unit acceleration, unit Newton.
forced expiratory volume (FEV) volume of air exhaled during a given time (usually the first second: FEV1).
forced vital capacity (FVC) the maximum gas volume that can be expelled from the lungs in a forced expiration.
forceps a surgical instrument with two opposing blades used to grasp or compress tissues, swabs, needles and other surgical appliances.
forensic dentistry the examination, interpretation and presentation of dentally related evidence in a legal context.
forensic medicine (medical jurisprudence, or ‘legal medicine’) the application of medical science to questions of law.
foreskin the prepuce or skin covering the glans penis.
formaldehyde toxic gas used as a disinfectant. Dissolved in water (formalin), it is used mainly for disinfection and the preservation of histological specimens.
fornix an arch; particularly referred to the vagina, i.e. the space between the vaginal wall and the cervix of the uterus.
FORTRAN a programming language which is between BASIC and machine code in difficulty.
forward bias is when a battery is connected across a PN junction the potential barrier is lowered to allow current to flow opp reverse bias.
four-dimensional ultrasound three-dimensional ultrasound with a real time, moving image.
fourchette a membranous fold connecting the posterior ends of the labia minora.
Fourier analysis the method of dividing an image into the various spatial frequency areas and expressing them in mathematical terms.
Fourier transform used in electronic signal processing, a signal is analysed by taking a timed sample to identify its frequencies and their amplitudes and then to express them as a sum of frequencies multiplied by amplitude. This figure can then be electronically manipulated to improve the digital image.
fovea a small depression or fossa; particularly the fovea centralis retinae, the site with many cones important for distinct colour vision.
fractional inspired oxygen concentration (FiO2) the concentration of oxygen in inspired gas, expressed as a fraction of 1 (for example, FiO2 0.6 equals 60% inspired oxygen concentration).
fractionation in radiotherapy it is the process of administering smaller doses of radiation over a period of time, excluding weekends, to minimize tissue damage. See also conventional fractionation, hyperfractionation, accelerated fractionation, accelerated hyperfractionation.
fracture loss in continuity of a bone as a result of injury or underlying pathology. See also Bennett’s fracture, closed fracture, Colles’ fracture, comminuted fracture, complicated fracture, compression fracture, depressed fracture, incomplete fracture, impacted fracture, open (compound) fracture, pathological fracture, Pott’s fracture, spontaneous fracture.
fragilitas ossium see osteogenesis imperfecta.
frame rate the number of times an ultrasonic image is refreshed per second, a slow frame rate gives better resolution, a high frame rate better demonstrates movement.
free induction decay a brief signal that occurs as the transverse magnetism decays towards zero following the application of a radio frequency pulse in magnetic resonance imaging.
Freiberg’s infarction death of bone tissue which most commonly occurs in the head of the second metatarsal bone.
Frenkel defect the loss of an atom from a structure forming an interstitial ion or atom.
Frenkel’s exercises special repetitive exercises to improve muscle and joint sense.
frenulum a small fold of mucous membrane that checks or limits the movement of an organ, for example, tongue, prepuce of the penis, frenulum linguae from the undersurface of the tongue to the floor of the mouth. Also called frenum.
frequency the number of cycles of alternating current, measured in Hertz, that occur in 1 second. In statistics, the number of times a particular value occurs. Ultrasound is frequencies beyond 20 kilohertz.
frequency distribution the number of times (frequency) each value in a variable is observed.
friable easily crumbled; readily pulverized.
Fricke dosimeter a chemical dosimeter containing a solution of ferrous sulphate in sulphuric acid; when the chemical is irradiated ferric sulphate is produced. The quantity produced is assessed by measuring the optical density before and after irradiation.
frog plaster conservative treatment of developmental dysplasia of the hip (congenital dislocation of the hip), whereby the dislocation is reduced by gentle manipulation and both hips are immobilized in plaster of Paris, both hips abducted to 80ö and externally rotated.
front pointer used in radiotherapy to indicate the central entry point of the radiation. See also back pointer.
frontal associated with the front of a structure. The bone of the forehead.
frontal plane a vertical plane running from head to foot. It divides the body into front and back parts and is at right angles to the median plane. Also called the coronal plane.
frontal sinus cavity at the inner aspect of each orbital ridge on the frontal bone.
frozen shoulder initial pain followed by stiffness, lasting several months. As pain subsides, exercises are intensified until full recovery is gained. Cause unknown.
fulcrum the point at which two objects pivot.
Fulfield applicator a secondary beam collimator with lead-lined sides which form a cone and a 3-mm thick Perspex end.
full-term mature – when pregnancy has lasted 40 weeks.
fume cupboard a cupboard with an external exhaust system to enable the handling of radioactive materials to prevent inhalation or ingestion of the dust or gaseous products.
fumigation disinfection using the fumes of a vaporized disinfectant.
function the ability to adapt consistently and competently to the demands of any normal situation in any normal environment. Describes the specific work done by a structure or organ in its normal state.
functional relating to function. Of a disorder, of the function but not the structure of an organ. As a psychiatric term, describes a condition without primary organic disease.
functional incontinence erratic and involuntary urinary incontinence in the absence of physical problems in bladder or nervous system. It may be due to immobility or cognitive defects.
fundus the basal portion of a hollow structure; the part which is distal to the opening. In ophthalmology the inner surface of the eye as viewed through the pupil using an ophthalmoscope.
fungate to grow rapidly and produce fungus-like growths, often occurs in the late stage of malignant tumours.
fungi simple plants. Mycophyta, including mushrooms, yeasts, moulds and rusts, many of which cause superficial and systemic disease in humans, such as actinomycosis, aspergillosis, candidiasis and tinea.
fungicide an agent that kills fungi. An addition to radiographic film emulsion, and developer to make them resistant to the growth of mould or bacteria.
fungiform resembling a mushroom, like the fungiform papillae of the tongue.
funiculus a cord-like structure.
funnel chest (pectus excavatum) a congenital deformity in which the breast bone is depressed towards the spine.
fusiform resembling a spindle.
fusiform aneurysm localized dilatation of an artery in which the circumference of the vessel is dilated.
