What is supraspinatus muscle?

Supraspinatus Muscle: Anatomy, Function, Clinical Significance, and Rehabilitation

Introduction

The supraspinatus muscle is one of the four rotator cuff muscles of the shoulder. Despite its relatively small size, it plays a significant role in both shoulder movement and stability. It is particularly important in initiating arm abduction and maintaining the humeral head’s position in the glenoid cavity.
Due to its location beneath the acromion, the supraspinatus is highly susceptible to overuse injuries, impingement, and degenerative changes, especially in individuals performing repetitive overhead movements such as athletes, manual laborers, and certain occupational workers.

Anatomy

Origin

• Supraspinous fossa of the scapula.

Insertion

• Superior facet of the greater tubercle of the humerus.

Nerve Supply

• Suprascapular nerve (C5, C6), derived from the upper trunk of the brachial plexus.

Blood Supply

• Suprascapular artery (branch of the thyrocervical trunk).

Function

• Primary Action: Initiates the first 15 degrees of shoulder abduction before the deltoid muscle takes over.

• Secondary Role: Stabilizes the humeral head during shoulder movements.

• Supportive Function: Works with other rotator cuff muscles to prevent dislocation.

Clinical Assessment

Palpation

• Position: Patient sitting or standing, arm relaxed.

• Procedure: Locate the spine of the scapula and palpate superiorly into the supraspinous fossa.

• Finding: Tenderness or atrophy suggests pathology.

Power Testing

• Position: Arm abducted ~15° in the scapular plane, thumb pointing downward.

• Procedure: Apply downward resistance while the patient holds position.

• Positive Result: Weakness or pain indicates possible supraspinatus injury.

Length Testing

• Rarely performed in isolation due to anatomical constraints, but surrounding muscle tightness can indirectly affect it.

Common Injuries

• Supraspinatus tendinopathy – overuse or degeneration of the tendon.

• Partial or full-thickness tears – often from trauma or chronic wear.

• Subacromial impingement syndrome – tendon irritation under the acromion.

• Calcific tendinitis – calcium deposits in the tendon causing pain.

• Rotator cuff syndrome – combined injury with other rotator cuff muscles.

Rehabilitation & Therapeutic Exercises

1. Isometric Abduction

• Position: Arm by the side.

• Procedure: Push arm outward gently against a wall without movement. Hold for 5–10 seconds.

• Purpose: Early-stage strengthening without joint stress.

2. Side-Lying External Rotation

• Position: Lie on the opposite side with the elbow bent at 90°.

• Procedure: Rotate the forearm upward, keeping the elbow close to the body.

• Purpose: Improves rotator cuff stability.

3. Scaption with Resistance Band

• Position: Standing, resistance band anchored at the feet.

• Procedure: Raise arms in the scapular plane to shoulder height.

• Purpose: Functional strengthening with low impingement risk.

Trigger Points

• Location: Deep in the supraspinous fossa.

• Referred Pain: Lateral shoulder and upper arm.

• Management: Manual therapy, stretching, myofascial release, and dry needling.

Summary Table

Feature	Details
Origin	Supraspinous fossa of scapula
Insertion	Superior facet of greater tubercle of humerus
Nerve Supply	Suprascapular nerve (C5, C6)
Blood Supply	Suprascapular artery
Primary Action	Initiates shoulder abduction (0–15°)
Common Injuries	Tendinopathy, tears, impingement

FAQs

1. What causes supraspinatus muscle pain?
Pain may result from overuse, poor posture, impingement, or rotator cuff injuries. Repetitive overhead movements are a common cause.

2. How can I strengthen my supraspinatus muscle?
Exercises like scaption, side-lying external rotation, and isometric abduction can strengthen the muscle safely.

3. What are the symptoms of a supraspinatus tear?
Common symptoms include shoulder pain, weakness in abduction, difficulty lifting the arm, and night pain when lying on the affected side.

4. Can a supraspinatus injury heal without surgery?
Mild to moderate injuries often improve with rest, physiotherapy, and activity modification, while severe tears may require surgical repair.

5. Is the supraspinatus tested separately from other rotator cuff muscles?
Yes, through specific manual muscle tests, it can be isolated for assessment.

References

1. Standring S. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 42nd ed. Elsevier; 2020.

2. Magee DJ. Orthopedic Physical Assessment. 6th ed. Elsevier; 2014.

3. Kisner C, Colby LA. Therapeutic Exercise: Foundations and Techniques. 7th ed. F.A. Davis; 2022.

4. Escamilla RF, Hooks TR, Wilk KE. "Optimal management of rotator cuff injuries and rehabilitation." Sports Health. 2014;6(2):156-165.

5. Lewis JS. "Rotator cuff related shoulder pain: Assessment, management and uncertainties." Manual Therapy. 2016;23:57-68.