Rotator Cuff of the Shoulder

January 12, 2021 || By : Dr. MhmadFarooq || Anatomy
| Last updated on January 16, 2021


What is the rotator cuff of the shoulder?

  • Rotator Cuff is a group of muscles surrounding the shoulder joint.
  • Rotator cuff consists of 4 muscles abbreviated in the word “SITS”:
    1. Supraspinatus muscle.
    2. Infraspinatus muscle.
    3. Teres minor muscle.
    4. Subscapularis muscle.
Supraspinatus Muscle
Originsupraspinous fossa of scapula.
Insertionsuperior facet on greater tuberosity of humerus.
InnervationSuprascapular nerve (C4, C5 and C6) (C4,C5, C6).
Arterial SupplySuprascapular artery.
ActionInitiates and assists deltoid in abduction of arm and acts with other rotator cuff muscles
Infraspinatus Muscle
OriginInfraspinous fossa of scapula.
InsertionMiddle facet on greater tuberosity of humeruss.
InnervationSuprascapular nerve (C5 and C6) (C5, C6).
Arterial SupplySuprascapular and circumflex scapular arteries
ActionLaterally rotate arm; helps to hold humeral head in glenoid cavity of scapula.
Teres minor muscle
OriginSuperior part of lateral border of scapula
InsertionInferior facet on greater tuberosity of humerus
InnervationAxillary nerve (C5 and C6) (C5, C6)
Arterial SupplySubscapular and circumflex scapular arteries
ActionLaterally rotate arm; helps to hold humeral head in glenoid cavity of scapula
Subscapularis muscle
OriginSubscapular fossa of scapula
InsertionLesser tuberosity of humerus
InnervationUpper and lower subscapular nerves (C5, C6 and C7) (C5, C6, C7)
Arterial SupplySubscapular artery
ActionMedially rotates arm and adducts it; helps to hold humeral head in glenoid cavity of scapula
  • The primary function of the rotator cuff is to provide dynamic stability by balancing the force couples about the glenohumeral joint in both the coronal and transverse plane.
    1. Coronal plane
      • the inferior rotator cuff (infraspinatus, teres minor, subscapularis) functions to balance the superior moment created by the deltoid
    2. Transverse plane
      • the anterior cuff (subscapularis) functions to balance the posterior moment created by the posterior cuff (infraspinatus and teres minor)

Rotator Cuff Footprint:

  • Footprint of the rotator cuff means the value of space of its insertion on the humeral head.
  1. Supraspinatus: Triangular in shape, with an average maximum medial-to-lateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm.
  2. Infraspinatus: Trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm.
  3. Teres minor: Triangular in shape, with an average maximum medial-to-lateral length of 29 mm and an average maximum width of 21 mm.
  4. Subscapularis: Comma-shaped insertion, with an average maximum medial-to-lateral length of 40 mm and an average maximum width of 20 mm.
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