The rotator cuff is an integral part of the shoulder joint. It helps to stabilizes the joint during almost every type of movement of the shoulder. The rotator cuff is composed of four muscles as well as the tendons that attach then to the bones of the joint and the nerves that control their motor movement. The American Academy of Family Physicians notes that the four skeletal muscles that compose the rotator cuff are the subscapularis, the infraspinatus, the supraspinatus and the teres minor. These muscles stabilize and support the shallow grooved shoulder joint by wrapping around the head of the upper arm or humerus bone. This provides stability and strength and allows the flexible range of movement that is controlled by the motor nerves.
Subscapular Nerves
The upper and lower subscapular nerves innervate the subscapularis muscle of the rotator cuff. This muscle begins at the scapular or shoulder blade and runs up to the head of the humerus or upper arm bone. The subscapularis is the deepest muscle of the rotator cuff and is located between the scapula and the rib cage, as described by MayoClinic.com.
Suprascapular Nerve
The suprascapular nerve innervates the infraspinatus muscle of the rotator cuff. This muscle originates from the edge of the scapula or shoulder blade bone and extends to the upper part of the humerus bone in the upper arm. This muscle helps to stabilize, strengthen and shoulder joint and allows it to rotate externally or outwards to face the palms forwards. MayoClinic.com notes that the suprascapular nerve also innervates the supraspinatus muscle, which works to abduct or raise the shoulder joint away from the body.
Axillary Nerve
The axillary nerve connects to the teres minor muscles and innervates it as well as the infraspinatus muscle to rotate the shoulder joint laterally or outwards. The University of Washington explains that the teres minor muscle originates at the lower, outer corner of the scapula and inserts at the humerus bone.
