SUPRASPINATUS MUSCLE: ORIGIN, INNERVATION, FUNCTION, PATHOLOGIES - ANATOMY AND PHYSIOLOGY - 2025

The supraspinatus muscle is a small, triangular-shaped, paired muscle. Its name comes from the Latin musculus supraspinatus. It is located in the fossa of the scapula that bears the same name "supraspinatus fossa". The supraspinatus fossa next to this muscle is located in the dorsal and superior part of the scapula.

A tendon of this muscle protrudes from the supraspinatus fossa and passes just below the acromion and the coraco-acromial ligament, and above the glenohumeral joint. In other words, they run through the subacromial space until they insert into the humerus trochiter.

Graphic representation of the supraspinatus muscle. Source: Mikael Häggström. When using this image in external works, it may be cited as: Häggström, Mikael (2014). "Medical gallery of Mikael Häggström 2014". WikiJournal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.008. ISSN 2002-4436. Public Domain.orBy Mikael Häggström, used with permission.. Edited image.

This muscle is part of the structural complex called the rotator cuff. Therefore, it protects the glenohumeral joint. This function is very important, as this is one of the most unstable shoulder joints.

The supraspinatus muscle cannot be easily palpated due to its deep location, since the trapezius muscle is located above it.

The tendon is protected by the subdeltoid bursa, preventing it from rubbing against the acromion, however, a narrowing at the level of the subacromial space can cause impingement of the supraspinatus tendon, generating a pathology known as supraspinatus tendinopathy or subacromial syndrome.

Origin

This muscle completely covers the surface of the supraspinatus fossa of the shoulder blade or scapula.

Insertion

Outside the supraspinatus fossa, the muscle emits tendons that are inserted in the upper area of ​​the humerus trochiter or also called the greater tuberosity of the humerus.

Innervation

The supraspinatus muscle is innervated by the suprascapular nerve. It also receives nerve branches from C5, and to a lesser extent from C4 and C6.

Irrigation

This muscle is supplied by the suprascapular artery.

Function

This muscle actively participates in the lifting movement of the upper limb.

On the other hand, the supraspinatus muscle together with the infraspinatus, teres minor and subscapularis provide stability to the glenohumeral joint, specifically these muscles prevent the head of the humerus from detaching from the glenoid cavity, especially when it is in motion.

Therefore, a coordinated contraction of the 4 muscles is necessary so that the central position of the humerus head in the glenoid cavity is not lost. In this sense, it can be said that the supraspinatus muscle acts in conjunction with the rest of the rotators to maintain the homeostasis of the joint.

The muscle compression exerted by the supraspinatus muscle is greater when the joint capsule and ligaments are relaxed.

Pathologies:

This pathology is also called the subacromial syndrome or impingement syndrome.

Due to their anatomical location, the muscles that make up the rotator cuff are highly susceptible to impingement injuries; but it should be noted that the most frequently affected is the supraspinatus muscle.

All the muscles that are part of the rotator cuff, including the supraspinatus, can be affected by trauma, postural problems, overuse of the glenohumeral joint, degeneration of muscle tissue, acromion shape, narrow subacromial space, among others.

Any of these causes can lead to supraspinatus tendon impingement syndrome.

A common ailment in the supraspinatus is the degeneration of its tissue due to lack of good vascularization at the level of the terminal portion of the tendon, approximately 1 cm from the insertion site.

Pain at the shoulder level tends to increase as the arm is raised, and pain is common at night. On palpation there is pain, difficulty moving the joint, and may be accompanied by weakness.

Classification of tendinopathies

Tendinopathy can be classified into three grades or stages.

Stage 1: there is a structural abnormality, without breakage.

Grade or stage 2: partial tendon tear.

Stage 3: complete tendon rupture.

Evaluation of the supraspinatus muscle

Jobe test

The Jobe test is specially designed to evaluate the function of the supraspinatus muscle.

The patient should place both arms forward and rotate them in such a way that the thumbs are pointing to the floor. Later the specialist will try to lower the arms while the patient resists this action.

This test has a high sensitivity. A positive reaction will be interpreted as follows: If there is pain during exercise, this means that a supraspinatus tendinopathy is present and if there is weakness it indicates a rupture of the same.

If instead there is no pain or weakness, the supraspinatus muscle is fine.

Drop arm test

This test also helps to evaluate the supraspinatus muscle. On this occasion, the specialist asks the patient to fully extend his arm and places the limb in question in 120 ° abduction.

The patient is asked to try to maintain that position and is subsequently told to lower the arm slowly. Some patients will not be able to hold the position. Another way to perform this test is by counter pressure while the patient performs the limb abduction movement.

Supraspinatus tear test

In this test, the specialist with one hand grasps the patient's elbow and with the other tries to palpate the injury at the shoulder level. To do this, he uses his fingers and with them he tries to locate the tendon insertion point on the glenohumeral joint. As it performs this action, the arm is rotated internally and externally.

Imaging studies

Initially, the radiographic study does not reveal changes, but in advanced cases the subacromial space can be shortened. For a more reliable diagnosis, ultrasound, tomography and computerized magnetic resonance imaging can be used.

Treatment of supraspinatus tendinopathy

Rotator cuff involvement should be treated as recently as possible after the initial injury, as the signs and symptoms, as well as the injury itself, worsen and complicate over time.

Physiotherapy

At the beginning of the painful shoulder syndrome it can be treated with physiotherapy, specifically it can be addressed with pendulum exercises.

These are capable of restoring joint mobility of the shoulder, however, there are controversies regarding their correct application. The exercises are called the Codman, Sperry, and Chandler pendulum.

On the other hand, these exercises are contraindicated in patients with a joint: infected, extremely painful, completely immobile (ankylosis) or in the period of consolidation of a fracture.

Sometimes it is also advisable as a treatment to carry out a few sessions with ultrasound plus microwave.

Surgical

When it comes to tendinopathies that are in their initial stage, one can resort to therapies, rest and oral anti-inflammatory drugs, but when the injury is quite serious or there is a rupture of the tendons, the treatment is almost always surgical. Today there are very effective and less invasive surgical techniques such as arthroscopy.

After arthroscopic surgery, the patient is discharged the next day and the sutures are removed after 10 days. For 6 to 8 weeks the patient can wear a sling without weight bearing.

At the end of the time, continue with exercises that strengthen the shoulder muscles, both intrinsic and extrinsic, until all mobility has been recovered.

References

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