Yes, the teres minor is one of the four muscles that make up the rotator cuff. It sits on the back of your shoulder blade and works alongside the infraspinatus to rotate your arm outward. The four rotator cuff muscles, sometimes remembered by the acronym SITS, are the supraspinatus, infraspinatus, teres minor, and subscapularis.
What the Teres Minor Does
The teres minor attaches along the outer edge of your shoulder blade and connects to the top of your upper arm bone (the humerus), just below where the infraspinatus attaches. Its primary job is external rotation of the shoulder, the motion you use when pulling your arm back to throw a ball or reaching behind your head.
Because the teres minor and infraspinatus share this external rotation role, they work as a functional pair. If one is weakened or injured, the other partially compensates. This overlap is why isolated teres minor problems can be tricky to identify on a standard physical exam.
How It Compares to the Other Three
Each rotator cuff muscle handles a different direction of shoulder movement:
- Supraspinatus: lifts your arm out to the side and is the most commonly torn rotator cuff muscle
- Infraspinatus: rotates your arm outward, working closely with the teres minor
- Teres minor: also rotates your arm outward, providing additional stability at the back of the shoulder joint
- Subscapularis: rotates your arm inward and helps hold it away from your body
Together, these four muscles form a “cuff” of tendons that wraps around the head of the humerus, keeping it seated in the shallow shoulder socket during movement. The shoulder joint sacrifices bony stability for its wide range of motion, so the rotator cuff is what prevents the ball from sliding out of the socket.
Nerve Supply and Why It Matters
The teres minor is powered by the axillary nerve, which originates from the C5 and C6 spinal nerve roots. This is the same nerve that controls the deltoid, the large muscle forming the rounded contour of your shoulder. An axillary nerve injury, whether from a shoulder dislocation, fracture, or compression, can weaken both the deltoid and the teres minor at the same time.
Notably, the infraspinatus runs on a completely different nerve (the suprascapular nerve). So even though the teres minor and infraspinatus do similar jobs, damage to the axillary nerve affects only the teres minor’s contribution to external rotation. The infraspinatus can still pick up some of the slack, which is why people with isolated axillary nerve injuries often retain partial external rotation strength.
Teres Minor Injuries
Isolated teres minor tears are uncommon compared to supraspinatus tears. In a review of 217 consecutive shoulder MRIs, only about 5.5% of patients showed isolated teres minor muscle wasting. Of those patients, 92% also had tears in other rotator cuff muscles or the labrum, suggesting that teres minor problems rarely happen in isolation.
When the teres minor does waste away on its own, the cause is often quadrilateral space syndrome. The quadrilateral space is a small anatomic tunnel bordered by the teres minor above, the teres major below, the long head of the triceps on one side, and the humerus on the other. The axillary nerve and a blood vessel pass through this space. Fibrous bands or cysts in the area can compress the nerve, gradually causing the teres minor to atrophy. On MRI, this shows up as fatty replacement of the muscle, sometimes with partial involvement of the deltoid.
Clinicians can test for teres minor dysfunction using the Hornblower’s test. You hold your arm up with the elbow bent and try to rotate your hand outward against resistance. If you can’t maintain that position, it points toward teres minor weakness, specifically involving the posterior branch of the axillary nerve.
Exercises That Target the Teres Minor
Because the teres minor and infraspinatus share the external rotation function, most rehab exercises work both muscles simultaneously. The American Academy of Orthopaedic Surgeons includes several in its standard rotator cuff conditioning program.
A good starting point is the side-lying external rotation: lie on your unaffected side, keep your elbow pinned to your ribcage, and slowly rotate your forearm upward against light resistance or gravity. As you progress, resistance band external rotation adds load. Stand with the band attached to a doorknob, hold it with your elbow bent 90 degrees at your side, and slowly rotate your forearm outward while keeping your elbow close to your body.
For a more advanced variation, external rotation with the arm raised to shoulder height targets the teres minor under greater demand. You hold a resistance band with your elbow bent 90 degrees and raised level with your shoulder, then rotate your hand upward until it’s in line with your head. Bent-over horizontal abduction, where you lie face down and raise a straight arm out to the side up to eye level, also engages the teres minor along with the middle and lower trapezius.
Stretching matters too. The sleeper stretch is one of the most commonly recommended: lie on your affected side with your arm bent in front of you, then use your other hand to gently push your forearm toward the floor until you feel a stretch in the back of your shoulder. Hold for 30 seconds, rest for 30 seconds, and repeat. Passive external rotation with a stick or dowel works similarly, gently pushing the shoulder into external rotation to maintain flexibility in the teres minor and infraspinatus.