Rotator Cuff: Subscapularis

The rotator cuff is composed of four muscles

  1. Supraspinatus – abduction
  2. Infraspinatus – external rotation
  3. Teres minor – external rotation
  4. Subscapularis – internal rotation

Rotator cuff injuries are incredibly common and it is helpful to figure out which of the four muscles is the major source of the problem (there is of course the possibility that multiple ones are injured/irritated).

For the subscapular (innervated by the suprascapular nerve C5,6) you can test internal rotation of the arm. The patient places the dorsum of their hand on their lower back. The examiner then pushes on the hand while the patient tries to lift the hand from the lower back. Pain or weakness is a positive test.

Rotator Cuff: Infraspinatus & Teres Minor

The rotator cuff is composed of four muscles

  1. Supraspinatus – abduction
  2. Infraspinatus – external rotation
  3. Teres minor – external rotation
  4. Subscapularis – internal rotation

Rotator cuff injuries are incredibly common and it is helpful to figure out which of the four muscles is the major source of the problem (there is of course the possibility that multiple ones are injured/irritated).

For the infraspinatus (innervated by the suprascapular nerve C5,6)  and the teres minor (innervated by the axillary nerve, C 5,6) you can test external rotation of the arm. The patient holds the arm next the body (adducted) with the elbow flexed to 90 degrees. The examiner then attempts to internally rotate the arm while the patient resists. Pain or weakness is a positive test.

Rotator Cuff: Supraspinatus (empty can test)

The rotator cuff is composed of four muscles

  1. Supraspinatus – abduction
  2. Infraspinatus – external rotation
  3. Teres minor – external rotation
  4. Subscapularis – internal rotation

Rotator cuff injuries are incredibly common and it is helpful to figure out which of the four muscles is the major source of the problem (there is of course the possibility that multiple ones are injured/irritated).

For the supraspinatus (innervated by the suprascapular nerve C5,6) you can do the “empty can test“. The patient holds out the affected arm (abducts) with elbow extended and wrist pronated. Like they were, in fact, pouring out a can of soda (or “pop” as we call it here). The examiner then pushes down on the extended arm and the patient tries to resist. Pain or weakness is a positive test.

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