The supraspinatus (plural ''supraspinati'') is a relatively small muscle of the upper back that runs from the supraspinous fossa superior portion of the

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

(shoulder blade) to the greater tubercle of the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a r ...

. It is one of the four rotator cuff muscles and also abducts the arm at the shoulder. The spine of the scapula separates the supraspinatus muscle from the

infraspinatus muscle In human anatomy, the infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa.''Gray's Anatomy'', see infobox. As one of the four muscles of the rotator cuff, the main function of the infraspin ...

, which originates below the spine.

Structure

The supraspinatus muscle arises from the supraspinous fossa, a shallow depression in the body of the scapula above its spine. The supraspinatus muscle

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

passes laterally beneath the cover of the

acromion In human anatomy, the acromion (from Greek: ''akros'', "highest", ''ōmos'', "shoulder", plural: acromia) is a bony process on the scapula (shoulder blade). Together with the coracoid process it extends laterally over the shoulder joint. The ...

. Research in 1996 showed that the postero-lateral origin was more lateral than classically described. The supraspinatus tendon is inserted into the superior facet of the greater tubercle of the

. The

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

attachments of the three rotator cuff muscles that insert into the greater tubercle of the humerus can be abbreviated as SIT when viewed from superior to inferior (for supraspinatus, infraspinatus, and teres minor), or SITS when the subscapularis muscle, which attaches to the lesser tubercle of the humerus, is included.

Nerve supply

The suprascapular nerve (C5) innervates the supraspinatus muscle as well as the

. It comes from the upper trunk of the

brachial plexus The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in t ...

. This nerve can be damaged along its course in fractures of the overlying

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the r ...

, which can reduce the person's ability to initiate the

abduction Abduction may refer to: Media Film and television * "Abduction" (''The Outer Limits''), a 2001 television episode * " Abduction" (''Death Note'') a Japanese animation television series * " Abductions" (''Totally Spies!''), a 2002 episode of an ...

Function

The supraspinatus muscle performs abduction of the arm, and pulls the head of the humerus medially towards the glenoid cavity. It independently prevents the head of the humerus from slipping inferiorly. The supraspinatus works in cooperation with the deltoid muscle to perform abduction, including when the arm is in an adducted position. Beyond 15 degrees the deltoid muscle becomes increasingly more effective at abducting the arm and becomes the main propagator of this action.

Clinical significance

The supraspinatus forms part of the rotator cuff and is one of its most frequently damaged components, whether from acute injury or gradual degeneration. Bad posture and age are leading risk factors, with a high prevalence of unsymptomatic partial and full tears, as well as symptomatic syndromes with chronic pain. Connected pathologies include acromial impingement, frozen shoulder, and poor sleep, especially on the side. Both ultrasound and MRI are now effective methods of diagnosis.

Tear

;Diagnosis Antero-posterior projectional radiography of the shoulder may demonstrate a high-riding humeral head, with an acromiohumeral distance of less than 7 mm. ;Repair One study has indicated that arthroscopic surgery for full-thickness supraspinatus tears is effective for improving shoulder functionality. A comparative effectiveness review of nonoperative and operative treatments for rotator cuff tears was performed at the University of Alberta Evidence-based Practice Center in 2010. The review identified one study which reported that, "Patients receiving early surgery had superior function compared with the delayed surgical group". The review noted that the level of significance of the study was not reported, and the review chose not to include it as one of their conclusions. Instead it concluded that "The paucity of evidence related to early versus delayed surgery is of particular concern, as patients and providers must decide whether to attempt initial nonoperative management or proceed immediately with surgical repair". In terms of operative techniques, differences in neither cuff integrity nor shoulder function were reported in studies comparing single-row versus double-row suture anchor fixation and mattress locking versus absorbable sutures. Postoperatively, a slight advantage was evident in patients who performed continuous passive motion alongside physical therapy, as opposed to those who solely performed physical therapy. There is insufficient evidence to adequately compare the effects of operative against nonoperative interventions. Complications were reported very seldom, or were not determined to be clinically significant.Seida J, Schouten J, Mousavi S, Tjosvold L, Vandermeer B, Milne A, Bond K, Hartling L, LeBlanc C, Sheps D. Comparative Effectiveness of Nonoperative and Operative Treatment for Rotator Cuff Tears. Comparative Effectiveness Review No. 22. (Prepared by the University of Alberta Evidence-based Practice Center under Contract No. 290-02-0023.) AHRQ Publication No. 10-EHC050. Rockville, MD: Agency for Healthcare Research and Quality. July 2010. Available at: www.effectivehealthcare.ahrq.gov/reports/final.cfm. A 2016 study evaluating the effectiveness of arthroscopic treatment of rotator cuff calcification firmly supported surgical intervention. Calcification of the supraspinatus tendon is a major contributor to shoulder pain in the general population and is often worsened following a supraspinatus tear. The results of the study included the return to sports and original functionality of 95.8% of the patients after a mean of 5.3 post-operative months. A significant decrease in pain was observed over time following removal of the calcification. The study showed the overall effectiveness of arthroscopic procedures on shoulder repair, and the lack of risk experienced. Before surgery, supraspinatus tendonitis should be ruled out as the cause of pain.

Additional images

File:Supraspinatus muscle animation.gif, Position of the supraspinatus muscle (shown in red). Animation. File:Arm muscles back numbers.png , Muscles around the left

shoulder The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder mak ...

, seen from behind.
3. Latissimus dorsi muscle
5. Teres major muscle
6. Teres minor muscle
7. Supraspinatus muscle
8.

Infraspinatus muscle In human anatomy, the infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa.''Gray's Anatomy'', see infobox. As one of the four muscles of the rotator cuff, the main function of the infraspin ...

13. long head of

Triceps brachii muscle The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of 3 parts: the medial, lateral, and long head. It is the muscle principally respon ...

. File:Shoulder motion with rotator cuff (supraspinatus).gif, Action of right supraspinatus muscle, anterior view. Three bones shown are

(top) and

coracoid process The coracoid process (from Greek κόραξ, raven) is a small hook-like structure on the lateral edge of the superior anterior portion of the scapula (hence: coracoid, or "like a raven's beak"). Pointing laterally forward, it, together with t ...

(center) of

, and

(left). File:Shoulder joint.svg, Diagram of the human shoulder joint, front view File:Shoulder joint back-en.svg, Diagram of the human shoulder joint, back view

References

External links

GoogleBody - Supraspinatus muscle
{{Authority control Muscles of the upper limb Rotator cuff Shoulder abductors