Teres minor
The smallest rotator cuff muscle, working alongside infraspinatus and easily confused with its larger namesake.
- Type
- Muscle
- Region
- Shoulder
- Standard name
- m. teres minor
- Origin
- Upper two-thirds of the lateral border of the scapula
- Insertion
- Inferior facet of the greater tubercle of the humerus
- Actions
- shoulder external rotationshoulder stabilisation
- Verify
- TA2 2459 TA98 A04.6.02.010
What it is
A narrow, rounded muscle running along the outer edge of the scapula to the back of the greater tubercle — teres means rounded. It is the smallest of the four cuff muscles and sits just below infraspinatus, blending with it closely enough that the two are difficult to separate by dissection in places.
It is not to be confused with teres major, which lies immediately below it, is not part of the rotator cuff, and does the opposite job. Two adjacent muscles with nearly the same name and opposing actions is an unusually unhelpful piece of anatomical naming.
Unlike the other three cuff muscles, it is supplied by the axillary nerve rather than the suprascapular or subscapular nerves.
What it does
Externally rotates the shoulder, with infraspinatus, and contributes to holding the humeral head in the socket.
Its line of pull also draws the head of the humerus downward as the arm elevates, which is part of how the joint keeps clearance overhead.
What loads it
External rotation against resistance, and deceleration of the arm in throwing. It cannot be loaded separately from infraspinatus.
What is commonly got wrong about it
Teres minor and teres major. Minor is a cuff muscle and externally rotates. Major is not a cuff muscle and internally rotates. They sit next to each other. The names tell you only their relative size.
That "the cuff" can be trained muscle by muscle. Three of the four attach within a couple of centimetres of one another and share a continuous tendon sleeve. Rotation work loads them together.