Teres Major Muscle Anatomy

Location & Overview

There teres major muscle is a small muscle of the upper back, which attaches to the humerus and the scapula. It is a thick muscle which is somewhat flat in shape. It is one of seven scapulohumeral muscles. The scapulohumeral muscles are: the deltoid, coracobrachialis, infraspinatus, subscapularis, supraspinatus, teres minor and the teres major. It has somewhat of a synergistic action with the latissimus dorsi so is occasionally referred to as the ‘lat’s little helper’ ^{[1] [2]}.

Here we can see an image of the teres major muscle from a posterior view.

Origin & Insertion

The teres major originates at the inferior angle of the medial border of the scapula and inserts at the medial crest of the intertubercular groove (also known as the bicipital groove). The bicipital groove is where the long head tendon of the biceps brachii is located ^{[3] [4]}.

The teres major originates from the posterior side of the scapula. Specifically, the inferior aspect of the medial border of the scapula.

The teres major inserts on the medial crest of the intertubercular groove. Also known as the bicipital groove.

Actions

The teres major can perform internal rotation of the humerus, shoulder extension and shoulder adduction ^{[5] [6]}.

Innervation

The teres major is innervated by the lower subscapular nerve (C5, C6, C7) ^[7].

Blood Supply

The teres major muscle gets its blood supply from one of the branches of the subscapular artery, either the circumflex scapular artery or the thoracodorsal artery ^{[8] [9]}.