Supraspinatus muscle

Supraspinatus Muscle Anatomy

The supraspinatus is a relatively small muscle of the upper back that runs from the supraspinatous fossa superior portion of the scapula (shoulder blade) to the greater tubercle of the humerus.

Supraspinatus with the other three muscles join to grouping rotator cuff and abduction of the shoulder joint is done. The spine of the scapula separates the supraspinatus muscle from the infraspinatus muscle, which originates below the spine.

This Muscle tendon overuse may lead to pain near the shoulder joint called supraspinatus Tendinitis.

Origin

It originates from the medial two-thirds of the supraspinous fossa of the scapula.

Insertion

It inserts into the upper impression of the greater tubercle of the humerus.

Nerve supply

The suprascapular nerve (c5-c6) supplies the muscle.

Blood supply

Arterial supply is from the suprascapular artery, a branch of the thyrocervical trunk of the subclavian artery. The suprascapular artery passes through the suprascapular notch, along with the suprascapular nerve to supply supraspinatus.
Sometimes supraspinatus receives a collateral blood supply via the dorsal scapular artery. Venous drainage is conveyed by the same-named veins which accompany the arteries and drain into the subclavian vein.

Lymphatic Drainage

In general, the arteries are followed by deep lymphatic drainage, and the veins by superficial lymphatic drainage. The inferior margin of the posterior axillary fold and the subscapular veins are home to the posterior subscapular nodes, which are the main lymphatic drainage points for the suprascapular region.

These nodes will drain efferently to the apical nodes and then to the central axillary nodes. The subclavian lymphatic trunk is made up of the combined efferent vessels. It can empty into the subclavian vein, the jugular lymphatic trunk, the jugulosubclavian venous junction, or infrequently a right lymphatic trunk. The thoracic duct is where the left trunk empties.

Action

Along with other short scapular muscles it steadies the head of the humerus during movements of the arm. Its main action is to abduct the shoulder joint from 0-15 is still controversial.

Function

While moving the glenohumeral joint, the supraspinatus muscle participates in the stabilization of the head of the humerus in the joint.
It also assists the deltoid muscle in the abduction of the arm at the glenohumeral joint.

Strengthening Exercise

• This muscle doing abduction of the shoulder joint mainly early abduction is with more to supraspinatus as compared to deltoid and as abduction is more than 30 degrees then deltoid muscle increases to work as compared to supraspinatus muscle.
• The goal of the exercise is to strengthen abductors in early 0-90 degrees during the initiation of shoulder abduction.
• Use of a Weight Cuff/Dumbbell in a standing position and then performing abduction of the shoulder up to 90 degrees and gradually releasing will strengthen the muscle.
• Repeat the maneuver. As exercise progresses, the use of theraband which targets early abduction movement with resistance is the best option for strengthening exercise.

Stretching Exercise

1. Elbow-Out Rotator Stretch

• Start standing or sitting tall. Place your left hand on the middle of your back, palm and elbow pointing out.
• Reach across the front of your body with your right hand and grab onto your left bicep or elbow.
• Gently pull forward.
• Hold for at least 30 seconds and then repeat on the other side.

Anatomical Variations

Aponeurotic enlargement of the supraspinatus tendon next to the bicipital groove is visible in approximately half of the MRI images analyzed in research investigations. This structure resembled a tendon and originated from the anterior part of the supraspinatus tendon, which traveled distally and parallel to the long head of the biceps tendon anterolaterally. Its distal insertion was on the superior side of the pectoralis major tendon.

The idea is that this aponeurotic expansion could strengthen the anterior tendon, which functions similarly to the rotator cable of the rotator cuff interval and has a small insertion imprint on the greater tuberosity.

Clinical Importance

Supraspinatus Tendinitis

• Supraspinatus tendinitis is a common and disabling condition that becomes more prevalent after middle age and is a common cause of pain in the shoulder joint. The main cause is resistive overuse.
• The muscle tendon of the rotator cuff is involved and affects the tendons of the musculoskeletal system and becomes degenerated, most often as a result of repetitive stresses and overloading during sports or occupational activities.
• The tendon of the Muscle commonly impinges under the acromion as it passes between the acromion and the humeral head. This mechanism is multi-factorial.

Rotator Cuff

• Four muscles around the scapula-to-shoulder region joint make the Rotator Cuff Muscle. The four muscles are Supraspinatus, Infraspinatus,  Teres minor, and Subscapularis.
• According to the first name of each muscle, they are also known as SITS. They arise from the scapular region and are inserted over the head of the Humerus -forming a cuff around the glenohumeral (GH) joint.
• They strengthen/stabilize the shoulder joint. Injury to this muscle Group may cause Rotator Cuff Injury.

The anatomical discrepancies in the anterior and posterior bellies of the supraspinatus muscle may account for the reported functional differences following injury. If the anterior belly is not ruptured and the anterior fibers are protected, the person’s ability to extend their arm above 90 degrees may be less affected.

It is crucial to monitor the structural integrity of the muscle and both halves during surgery in order to facilitate appropriate rehabilitation measures and gain a better understanding of post-operative recovery and functional ability.

Effective communication among all members of the healthcare team can enhance the best potential outcome for a patient with supraspinatus pathology. The muscle part that is pathologically involved, whether the rotator cuff interval is surgically closed or injured, and if the anterior fibers were engaged in the tear and repair are all crucial for optimal outcomes.

For radiological identification, conservative treatment, surgical decision-making, and post-operative rehabilitation, effective collaboration is crucial.

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