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Rotator Cuff

In the human body, the rotator cuff is a functional anatomical unit located in the upper extremity.

It consists of the following muscles:

  • supraspinatus muscle
  • infraspinatus muscle
  • teres minor muscle
  • subscapularis muscle

The following article describes the anatomy, function and pathologies of the rotator cuff.

Origins and insertions

These muscles all originate from the scapula and insert in the humerus.

Recommended video: Rotator cuff muscles
Origins, insertions, innervation and functions of the rotator cuff muscles.

Subscapularis muscle

The subscapularis muscle is very important for the internal rotation of the humerus. It arises from the subscapular fossa and inserts on the lesser tubercle of the humerus.

Subscapularis muscle - ventral view

Subscapularis muscle - ventral view

Teres minor muscle

The teres minor muscle originates from the lateral scapula border and inserts on the greater tubercle of the humerus.

Teres minor muscle - dorsal view

Teres minor muscle - dorsal view

Supraspinatus muscle

The supraspinatus muscle has its origin in the supraspinatous fossa and inserts on the greater tubercle of the humerus – similar to the teres minor muscle.

Supraspinatus muscle - dorsal view

Supraspinatus muscle - dorsal view

Infraspinatus muscle

The fourth muscle of the rotator cuff is the infraspinatus muscle. It originates in the infraspinatous fossa of the shoulder blade and inserts on the greater tubercle as well.

Infraspinatus muscle - dorsal view

Infraspinatus muscle - dorsal view

Functions

The main function of the rotator cuff is to stabilize and center the humeral head in the joint socket, the glenoid cavity. In addition, the muscles tighten the joint capsule preventing a pinch during shoulder movements.

Certainly the rotator cuff – as the name suggests – plays a major role in the internal and external rotation of the upper arm in the shoulder joint. All the muscles mentioned above fulfill different functions.

The subscapularis muscle is a powerful internal rotator which also supports the upper arm during abduction and adduction. Conversely, the teres minor muscle’s function consists primarily of external rotation, partly retroversion and adduction as well.

The supraspinatus muscle performs abduction of the shoulder, especially abduction over 60 degrees. Finally, the infraspinatus muscle is a strong external rotator and additionally assists in both abduction and adduction.

Clinical aspects

When looking at pathologies of the rotator cuff – as in all joints - one needs to differentiate between degenerative and traumatic lesions. Here are two examples:

An example of a degenerative disease of the rotator cuff is the subacromial impingement syndrome. There the supraspinatus muscle tendon gets impinged at the acromion. This process is commonly caused by a thickened tendon or an inflammation of the overlying bursa leading to an enlargement, thus compressing the subacromial space.

Another possible cause for an impingement is a bony subacromial spur resulting in a narrowing of the nerve with pain. A positive Neer sign when elevating the shoulder above 120 degrees is characteristic in the impingement syndrome.

The rotator cuff tear is an example of a traumatic lesion of the rotator cuff where it comes to a rupture of one or more tendons up to the point of a complete tear of the rotator cuff muscles. Often those ruptures have been preceded by degenerative changes in the rotator cuff. The treatment can be either of conservative or surgical nature (e.g. transosseous fixation), depending on the severity of the rupture and the patient’s age.

Even though the rotator cuff consists only of four muscles, it plays an essential role in the stability and mobility of the most flexible joint in the human body: the shoulder.

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Show references

References:

  • Benninghoff/Drenckhahn: Anatomie, Band 1, 16. Auflage, Urban & Fischer Verlag (2003)
  • Berchtold: Chirurgie, 6. Auflage, Elsevier Verlag (2008)
  • Rössler H., Rüther W. [Hrsg.]: Orthopädie und Unfallchirurgie, 19. Auflage, Elsevier Verlag (2005)

Author & Layout:

  • Christopher A. Becker
  • Achudhan Karunaharamoorthy

Illustrators:

  • Subscapularis muscle - ventral view - Yousun Koh

  • Teres minor muscle - dorsal view - Yousun Koh

  • Supraspinatus muscle - dorsal view - Yousun Koh

  • Infraspinatus muscle - dorsal view - Yousun Koh

  • Supraspinatus muscle - functional position - Yousun Koh

© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

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