The shoulder is made up of several layers, including the following:
- Bones. The collarbone (clavicle), the shoulder blade (scapula), and the upper arm bone (humerus).
- Joints. The place where movement occurs, including the following:
- Sternoclavicular joint (where the clavicle meets the sternum)
- Acromioclavicular (AC) joint (where the clavicle meets the acromion)
- Shoulder joint (glenohumeral joint). A ball-and-socket joint that facilitates forward, circular, and backward movement of the shoulder.
- Ligaments. A white, shiny, flexible band of fibrous tissue that holds joints together and connects various bones, including the following:
- Joint capsule. A group of ligaments that connect the humerus to the socket of the shoulder joint on the scapula to stabilize the shoulder and keep it from dislocating.
- Ligaments that attach the clavicle to the acromion
- Ligaments that connect the clavicle to the scapula by attaching to the coracoid process
- 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. Help support and rotate the shoulder in many directions. Facilitate movement of the shoulder.
- Rotator cuff. Name of a group of muscles and tendons that rotate the shoulder.
- 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.