Teres major
Not a rotator cuff muscle, despite its position and its name — it is effectively a small partner to latissimus dorsi.
- Type
- Muscle
- Region
- Shoulder
- Standard name
- m. teres major
- Origin
- Lower third of the lateral border and inferior angle of the scapula
- Insertion
- Medial lip of the intertubercular groove of the humerus
- Actions
- shoulder extensionshoulder adductionshoulder internal rotation
- Verify
- TA2 2462 TA98 A04.6.02.011
What it is
A thick, rounded muscle running from the lower corner of the scapula to the front of the humerus, sitting immediately below teres minor.
Despite lying among the cuff muscles it is not part of the rotator cuff. Its tendon does not blend with the joint capsule, it attaches to the front of the humerus rather than the greater tubercle, and it does not contribute to centring the joint.
Its tendon inserts alongside that of latissimus dorsi, and the two are sometimes described as functionally paired — one long muscle from the back and one short one from the shoulder blade, pulling the arm the same way. It is occasionally nicknamed "lat's little helper".
What it does
Extends, adducts and internally rotates the shoulder — pulls the arm down, in and inward. The same three actions as latissimus dorsi.
What loads it
Pulling movements: anything drawing the arm downward or backward against resistance. Pull-ups, rows, and pulldowns load it with latissimus dorsi.
The pull-up, negative pull-up and inverted row all load it alongside latissimus dorsi, which is the only way it is ever loaded.
What is commonly got wrong about it
That it is a rotator cuff muscle. It is not, on any of the criteria — attachment, capsule blending, or function. Its position among the cuff muscles and its similarity in name to teres minor make this a very common error.
That it can be trained separately from latissimus dorsi. It performs the same three actions in the same movements. Nothing selects it.
The name. Teres major and teres minor are neighbours with near-identical names, opposite rotations, and different memberships of the cuff. It is worth checking which one a source means.