The shoulder complex is a ball and socket joint and is comprised of 4 main muscles, several bones, and several soft tissue structures. The scapula (shoulder blade), clavicle (collar bone), and humerus (upper arm bone) make up the bony components.
A portion of your scapula called the glenoid articulates with the head of your humerus. To stabilize the ball and socket articulation, strong fibrous tissue called the labrum, deepens this socket. In addition to the labrum, additional ligaments attached around the joint create additional stability and functionality.
The primary muscles of the shoulder can be divided into two groups called scapulothoracic and scapulohumeral. The scapulothoracic muscles are comprised of the trapezius, rhomboids, and serratus anterior. Their job is to help stabilize the shoulder complex to the thoracic spine or mid back. The scapulohumeral muscles consist of the main movers of the shoulder joint the rotator cuff and deltoid. The rotator cuff and consists of the supraspinatus, infraspinatus, teres minor and subscapularis. The rotator cuff and deltoid work together to provide additional stability and function to the shoulder complex.