What is the functional anatomy of dynamic stabilizers of the shoulder in rotator cuff injuries?

Updated: Oct 25, 2018
  • Author: Gerard A Malanga, MD; Chief Editor: Craig C Young, MD  more...
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Answer

Dynamic stabilizers [14] include the rotator and scapular stabilizers (ie, teres major, rhomboids, serratus anterior, trapezius, levator scapula). The rotator cuff is composed of 4 muscles: the supraspinatus, infraspinatus, subscapularis, and teres minor. The supraspinatus is the principal supporting and kinetic muscle of the shoulder. The primary function of the rotator cuff muscles is to stabilize the GH joint so that the larger shoulder movers (eg, deltoid, latissimus dorsi) can carry out their function without significant motion of the humeral head on the glenoid. Increased movement results in shearing forces across the joint (to the labrum, in particular) and may result in humeral head migration and impingement upon the rotator cuff muscles and tendons.

The rotator cuff muscles are associated and assist with some shoulder motion; however, their main function is to provide stability to the joint by compressing the humeral head on the glenoid. The supraspinatus assists in shoulder abduction by maintaining the humeral head centered on the glenoid, with the middle deltoid acting as the primary mover. These muscles act as force couples, because they work synergistically to carry out a particular movement.


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