Bursocentesis

Bursography

Bursotomy

Cartilage

Cartilage is composed of collagen fibers and cartilage cells (chondrocytes). Together, these substances form its internal structure termed a matrix.

Three varieties of cartilage (elastic cartilage, fibrocartilage, and hyaline cartilage) form flexible tissues in different locations in the body.

The covering of the elastic and hyaline cartilage (with the exception of the articular cartilage) is called the perichondrium, which is instrumental in supplying the tissue with nutrients. Cartilage lacks a nerve supply, which means that wear and tear joint disease is not sensed until pain is registered by the bones. Also, because cartilage is avascular (meaning that it does not have a blood supply), disorders of the cartilage are often slow to heal.

Bone

As opposed to cartilage, bones (osseous tissue) are inflexible structures. There are two types of osseous tissue: cortical (also called compact) and cancellous (also called spongy or trabecular) bone (Fig. 3-2). The cortical bone is the dense, stronger, outer segment of bones, whereas cancellous bone is the more open, weaker part.

Skeleton

The Greeks named the skeleton for the dried up remains of a withered corpse. Today we recognize the term skeleton to represent the bones of the body without any of the muscles, ligaments, bursae, or tendons that accompany the musculoskeletal system, regardless of their state of hydration.

A normal skeleton is composed of 206 bones (slight variation occurs in the tailbone and knee bones), many of which are paired with a mirrored left or right likeness. For the purposes of assigning accurate codes, it is necessary to learn the names of each of these 206 bones, categorize them as to their location, and note when a disease or condition affects either the right, left, or bilateral locations (e.g., right, left, or both knee joints).

The skeleton itself can be divided into two parts: the axial skeleton, which is the skull, vertebrae (back bones), and rib cage, and the appendicular skeleton, which is the shoulder and pelvic girdles, and the upper and lower extremities (Fig. 3-1). The shoulder girdle connects the arms to the axial skeleton with the shoulder blades (scapulae) and collarbones (clavicles). The pelvic girdle provides attachment for the legs with its two pelvic (coxal) bones.

Bone Shapes

Bones can be divided by their shapes: long, short, flat, irregular, and sesamoid. Although the shape is often important to their supportive or protective functions (long—mostly those of the arms, legs, fingers and toes; short—boxy, cube-shaped like those of the wrist or ankle; flat—like the sternum, scapulae, and most of the skull bones; irregular—the vertebrae and hip bones; and sesamoid—the kneecap), the structure of these shapes is of particular importance to understanding the terminology needed for ICD-10. Long bones, for example, the upper arm bone, help to explain the different types of osseous tissue and the composition of bone at a microscopic and macroscopic level.

Shapes of Human Bones

Types	Examples
long bones	humerus (upper arm bone), femur (thigh bone)
short bones	carpal (wrist bone), tarsal (ankle bone)
flat bones	sternum (breastbone), scapula (shoulder blade)
irregular bones	vertebra (backbone), stapes (a bone in the ear)
sesamoid	patella (kneecap)

 Note

Although the traditional method of explaining the organization of the skeleton is by dividing it into its axial and appendicular components, the ICD-10-PCS Medical Surgical section categorizes the skeleton into three different divisions (Fig. 3-3):

• Head and facial bones: the skull, facial bones, and hyoid bone.

• Upper bones: the left and right upper extremities (arm, hand, and finger bones); left and right glenoid cavity; scapula; clavicle; rib; and the sternum, as well as the cervical and thoracic vertebrae.

• Lower bones: the left and right lower extremities (leg, foot, and toe bones), left and right pelvic bones (ilium, ischium, and pubis), acetabula, and the lumbar vertebrae, sacrum, and coccyx.

Bone Structure

The shaft of a long bone (Fig. 3-4) is termed the diaphysis, whereas the ends are called the epiphyses (sing. epiphysis). The end that is closer to the trunk is termed the proximal epiphysis, whereas the end that is farther away is called the distal epiphysis. The growth plate (also called the epiphyseal plate or the physis) is the site of growth for bone lengthening. This plate is “sealed” when growth stops, typically around the ages of 18-20 in most people.

The tissue that surrounds the bones is called the periosteum, which has specialized cells called nociceptors to provide the sensation of pain when damage occurs.

The inner lining of the center of the bones is called the endosteum. The medullary (medull/o) cavity is the center of the bone within the endosteum. There are two types of bone marrow in the medullary cavities. Red bone marrow produces blood cells, whereas yellow bone marrow stores fat. The yellow bone marrow is stored in the center of the cortical (compact) bone, whereas the red marrow is located in the spongy bone of long bones as well as the flat bones of the body. Stored in the center of long bones, yellow bone marrow is composed of fat, and red bone marrow gives rise to the stem cells that differentiate into red blood cells, platelets, and most of the white blood cells.

diaphysis

 dia- = through

 -physis = growth, nature

epiphysis

 epi- = above

 -physis = growth, nature

periosteum

 peri- = surrounding

 oste/o = bone

 -um = structure

endosteum

 endo- = within

 oste/o = bone

 -um = structure

bone marrow = myel/o

16. Osteoblasts ______________________ bone, whereas osteoclasts ______________________ bone.

17. The shaft of a long bone is called the ______________________; the ends of a long bone are called ______________________(plural!).

18. The outer covering of bone is the _______________________________________, whereas the inner lining is the ______________________.

19. A foramen, a sinus, and a fossa are examples of bone _________________________________. A condyle, a trochanter, and a tuberosity are examples of bone ______________________________________________.

20. A synonym for a sinus is a/an ___________________________________________________________________.

21. What are the five bone shapes? __________________________________________________________________.

22. The axial skeleton comprises ____________________________________________________________________.

23. The appendicular skeleton comprises _____________________________________________________________.

24. The ICD-10-PCS divides the entire skeleton into three categories. What are they? _______________________________________________________________________________________________.

25. Describe the difference between cortical and cancellous bone. ____________________________________.

Skull

The skull is made up of two parts: the cranium that encloses and protects the brain and the facial bones (Fig. 3-5).

Rib Cage

The ribs (costa) consist of 12 pairs of thin, flat bones attached to the thoracic vertebrae in the back and to costochondral tissue in the front (Fig. 3-6). The head and neck of the ribs are closest to the vertebrae. The ribs can be categorized as follows:

In addition to ribs, the rib cage includes the sternum, also known as the breastbone. The sharp point at the most inferior aspect of the sternum is called the xiphoid process. The combing form xiph/o is derived from the Greek word for sword, which the xiphoid resembles.

The corporis (body) of the sternum is the main central portion. The manubrium is the upper section that articulates with the collarbones. Manubri/o means “handle,” a reference to the swordlike xiphoid process. The suprasternal notch (also called the jugular notch and fossa jugularis sternalis) is the small indentation in the superior edge of the manubrium.

Spine

The spinal or vertebral column is divided into five regions from the neck to the tailbone. It is composed of 26 bones called the vertebrae (Fig. 3-6). The following table lists the bones in the spine.

C1 is called the atlas for the Greek god who held up the world. C2 is called the axis for its role in permitting rotation of the head. Unique to C2 is the dens (also termed the odontoid process), which is a small, toothlike projection for the first cervical vertebra to rotate around.

The vertebral foramen is the opening in the center of each vertebra where the spinal cord passes. The vertebral arch (also called the neural arch) is the posterior part of the bone. It consists of two laminae, the spinous process, the vertebral pedicles, and the facets. Laminae are thin, platelike structures that form parts of the arch on either side of the spinous process. The spinous process is the thornlike projection on the back of a vertebra. Vertebral pedicles connect the laminae to the vertebral body. Facets are small, rounded processes that articulate between vertebrae. Also called articular processes, they are either inferior or superior.

Upper Appendicular Skeleton

The upper appendicular skeleton (Fig. 3-7) includes the shoulder girdle (scapula, clavicle, upper humerus) and the arm bones. Refer to Fig. 3-8A for a closer look at the shoulder.

Lower Appendicular Skeleton

The lower half of the appendicular skeleton can be divided into the pelvic girdle (the bony pelvis, sacrum, and coccyx) and the leg bones (Fig. 3-9). The pelvis is composed of two coxal (hip) bones that are connected in the front at the pubic symphysis and in the back at the sacrum. Each coxa is composed of three fused bones that together form the hip socket, the acetabulum, for the head of the thighbone. The three fused bones are the:

The leg is composed of the: