Scapular muscles


Opposed to the axial muscles are the scapular muscles. These muscles include the teres minor and teres major, the supraspinatus and the infraspinatus, the deltoid, the subscapularis, and the coracobrachialis muscles.


The teres minor muscle is responsible for the lateral rotation of the arm at shoulder level, but can only do so in conjunction with the infraspinatus muscle.

The teres major muscle is responsible for the medial rotation as well as adduction of the shoulder, and it functions almost identically to the latissimus dorsi.

The supraspinatus muscle works cohesively with the deltoid muscle to achieve adduction and lateral rotation of the shoulder joint. Lateral rotation of the arm occurs via the infraspinatus muscle.


Scapular muscles
Image: Scapular Muscles

The deltoid muscle is considered the primary scapular muscle of the shoulder, and it is not only used commonly as a site for medicinal injections, it is also relies on the antagonistic qualities of the pectoralis major and the latissimus dorsi muscle for adduction of the shoulder joint. The deltoid muscle is easily discernable as the thick muscle that appears to encapsulate the crown of the shoulder.

The subscapularis muscle assists in medial rotation of the arm at shoulder level, but its primary responsibility is to provide structural stability for the shoulder joint and the arm. The coracobrachialis works in cohesive unity with the pectoralis major to provide the shoulder joint with flexing and adducting capabilities.
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