rotator cuff

• Supraspinatus

  O: Medial 2/3 of the supraspinous fossa

  R: Laterally

  I: Tendon forms within the muscle as it passes laterally below trapezius, the acromion process and the coracoacromial ligament. Tendon blends in with superior aspect of the GH joint capsule. Inserts into upper facet on the greater tubercle of humerous

  A: Initiates abduction of GHJ

  NS: Suprascapular nerve (C(4), 5, 6)

  
  

  Function: Holds the head of humerus against the glenoid fossa to prevent upward shearing
• Infraspinatus:

  O: Medial 2/3 of the infraspinous fossa of scapular

  R: Laterally and merge to a narrow tendon

  I: Middle facet on the greater tubercle of humerus. Bursa separates tendon from posterior part of GH joint

  A: Lateral rotation of GHJ

  NS: Suprascapular nerve (C(4), 5, 6)

  
  

  Function: Stabilises the head of humerus in the glenoid fossa during GHJ movements with other RC muscles
• Teres Minor:

  O: Upper 2/3 of the lateral border of the scapula

  R: Upwards and laterally

  I: Lowest facet on the greater tubercle via a narrow tendon which also reinforces the posterior part of the capsule

  A: Lateral rotation in the anatomical position; adducts the abducted arm

  NS: Axillary nerve (C5, 6)

  Function: Resists upward displacement of HOH during active contraction of deltoid
• Subscapularis:

  O: Medial 2/3 of the sub-scapular fossa

  R: Fibres wind around head of humerus anteriorly

  I: Fibres narrow to insert into the lesser tubercle of humerus via a broad thick tendon. Bursa separates the tendon from the scapula neck

  A: Medial rotation and adduction of the GHJ

  NS: Upper and Lower subscapular nerves (C5, 6, 7)

  Function: Holds head of humerus in glenoid fossa, resisting upward displacement during active contraction of biceps, triceps and deltoids