Facts About the Spine, Shoulder, and Pelvis

Facts about the shoulder

The shoulder is made up of several layers:

• Bones. These include the collarbone (clavicle), the shoulder blade (scapula), and the upper arm bone (humerus).
• Joints. These facilitate movement and include the following:
• Ligaments. White, shiny, flexible bands of fibrous tissue, which hold joints together and connect the various bones, including the following:
• Acromion. The roof (highest point) of the shoulder that is formed by a part of the scapula.
• Tendons. The tough cords of tissue that connect muscles to bones. The rotator cuff tendons are a group of tendons that connect the deepest layer of muscles to the humerus.
• Muscles. These help support and rotate the shoulder in many directions.
• Bursa. A closed space between 2 moving surfaces that has a small amount of lubricating fluid inside; located between the rotator cuff muscle layer and the outer layer of large, bulky muscles.
• Rotator cuff. Composed of tendons, the rotator cuff and associated muscles hold the ball tightly within the glenohumeral joint at the top of the upper arm bone (humerus).

Facts about the spine

The vertebral column, also called the spine or backbone, is made up of multiple vertebrae that are separated by spongy disks. The spine is classified into several distinct areas:

• The cervical area consists of 7 bony parts in the neck.
• The thoracic spine consists of 12 bony parts in the back area.
• The lumbar spine consists of 5 bony segments in the lower back area; 5 sacral* bones; and 4 coccygeal* bones (the number of coccygeal bones can vary from 3 to 5). (* By adulthood, the 5 sacral vertebrae fuse to form one bone, and the 4 coccygeal vertebrae fuse to form one bone.)

Facts about the pelvis

The pelvis is a basin-shaped structure that supports the spinal column and protects the abdominal organs. It contains the following:

• Sacrum. A spade-shaped bone that is formed by the fusion of 5 originally separate sacral vertebrae.
• Coccyx (tailbone). This is formed by the fusion of 4 originally separated coccygeal bones.
• Pelvic (hip) bones. These are: