Is the supraspinatus muscle part of the rotator cuff and involved in rotator cuff syndrome?

Yes, the supraspinatus is a core component of the rotator cuff and is the most frequently involved muscle in rotator cuff syndrome.

Anatomical Composition of the Rotator Cuff

The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis, which together form a musculotendinous unit providing dynamic stability to the shoulder joint. 1

• The supraspinatus is positioned superiorly in the rotator cuff complex 2
• The infraspinatus and teres minor are located posteriorly 2
• The subscapularis occupies the anterior position 2

Supraspinatus Role in Rotator Cuff Syndrome

The supraspinatus is the most commonly injured tendon in rotator cuff pathology, though this traditional understanding has been refined by anatomical studies. 3, 4

Primary Involvement Patterns:

• Isolated supraspinatus tears are the most frequent presentation in rotator cuff syndrome, occurring more commonly than combined injuries 4
• The supraspinatus tendon is particularly vulnerable to subacromial impingement, where it becomes compressed against the anterolateral acromion during overhead activities 5
• Supraspinatus tendon irritation due to subacromial outlet obstruction is a key pathophysiological mechanism in impingement syndrome 5

Clinical Manifestations When Supraspinatus is Involved:

• Pain in the anterior or anterolateral shoulder that worsens with overhead activities 5
• Weakness on abduction of the shoulder 1
• Pain during the arm cocking and acceleration phases of throwing motions 5
• Positive Neer's test (88% sensitivity) and Hawkins' test (92% sensitivity) 5

Important Anatomical Considerations

The supraspinatus footprint on the greater tuberosity is much smaller than historically believed (average 6.9 mm medial-to-lateral, 12.6 mm anteroposterior), with the infraspinatus actually occupying a substantial portion of what was previously attributed to supraspinatus territory. 3 This explains why infraspinatus atrophy is frequently observed even with small to medium-size rotator cuff tears that appear to primarily involve the supraspinatus. 3

Progression and Complications

• Untreated supraspinatus pathology can progress to tendon degeneration and full-thickness tears 5
• The supraspinatus experiences repetitive eccentric stress during overhead activities, leading to fatigue and injury 5
• Partial supraspinatus tendon tears are more common than complete tears in the early stages of rotator cuff syndrome 4

Diagnostic Confirmation

• MRI shows 90% sensitivity and 80% specificity for detecting supraspinatus tendon abnormalities in impingement syndrome 5
• Radiographs may reveal calcific deposits within the supraspinatus tendon in chronic cases 1
• The supraspinatus can be injured at various locations: within the tendon substance, at the bone insertion, or rarely at the musculotendinous junction 6