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”:
- Supraspinatus muscle.
- Infraspinatus muscle.
- Teres minor muscle.
- Subscapularis muscle.
Supraspinatus Muscle | |
---|---|
Origin | supraspinous fossa of scapula. |
Insertion | superior facet on greater tuberosity of humerus. |
Innervation | Suprascapular nerve (C4, C5 and C6) (C4,C5, C6). |
Arterial Supply | Suprascapular artery. |
Action | Initiates and assists deltoid in abduction of arm and acts with other rotator cuff muscles |
Infraspinatus Muscle | |
---|---|
Origin | Infraspinous fossa of scapula. |
Insertion | Middle facet on greater tuberosity of humeruss. |
Innervation | Suprascapular nerve (C5 and C6) (C5, C6). |
Arterial Supply | Suprascapular and circumflex scapular arteries |
Action | Laterally rotate arm; helps to hold humeral head in glenoid cavity of scapula. |
Teres minor muscle | |
---|---|
Origin | Superior part of lateral border of scapula |
Insertion | Inferior facet on greater tuberosity of humerus |
Innervation | Axillary nerve (C5 and C6) (C5, C6) |
Arterial Supply | Subscapular and circumflex scapular arteries |
Action | Laterally rotate arm; helps to hold humeral head in glenoid cavity of scapula |
Subscapularis muscle | |
---|---|
Origin | Subscapular fossa of scapula |
Insertion | Lesser tuberosity of humerus |
Innervation | Upper and lower subscapular nerves (C5, C6 and C7) (C5, C6, C7) |
Arterial Supply | Subscapular artery |
Action | Medially 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.
- Coronal plane
- the inferior rotator cuff (infraspinatus, teres minor, subscapularis) functions to balance the superior moment created by the deltoid
- Transverse plane
- the anterior cuff (subscapularis) functions to balance the posterior moment created by the posterior cuff (infraspinatus and teres minor)
- Coronal plane
Rotator Cuff Footprint:
- Footprint of the rotator cuff means the value of space of its insertion on the humeral head.
- 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.
- 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.
- Teres minor: Triangular in shape, with an average maximum medial-to-lateral length of 29 mm and an average maximum width of 21 mm.
- 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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