Teres major forms the posterior axillary fold with latissimus dorsi. It is sometimes called "lat's little helper" as it acts synergistically with latissimus. The triangular interval (inferior to teres major, lateral to long head of triceps) contains the radial nerve and profunda brachii.
| Origin | Posterior surface of the inferior scapular angle |
|---|---|
| Insertion | Medial lip of the bicipital groove — posterior to latissimus insertion |
| Nerve Supply | Lower subscapular nerve (C5, C6, C7) |
| Blood Supply | Circumflex scapular artery |
| Actions | Adducts and medially rotates the humerus; Extends the humerus from a flexed position |
|---|
Teres major is used in tendon transfer to restore external rotation in irreversible subscapularis tears. In posterior axillary fold flaps for axillary reconstruction, teres major is included. Its insertion at the bicipital groove medial lip is just posterior to latissimus — a key distinguishing feature in MRI anatomy.
Palpated on the posterior lateral chest wall as the posterior axillary fold during resisted adduction.
Teres major tendon transfer to the lesser tuberosity restoring medial rotation in irreparable subscapularis tears.
