In anatomy, the rotator cuff or rotor cuff is the group of muscles and their tendons that act to stabilize the shoulder. The four muscles of the rotator cuff, along with the teres major and the deltoid, make up the six scapulohumeral (those that connect to the humerus and scapula and act on the glenohumeral joint) muscles of the human body.
The rotator cuff muscles are important in shoulder movements and in
maintaining glenohumeral joint (shoulder joint) stability.
These muscles
arise from the scapula and connect to the head of the humerus forming a
cuff at the shoulder joint. They hold the head of the
humerus in the small and shallow glenoid fossa of the scapula.
The
glenohumeral joint is often likened to a golf ball (head of the humerus)
sitting on a golf tee (glenoid fossa).
During abduction of the arm, the
rotator cuff compresses the glenohumeral joint, a term known as
concavity compression, in order to allow the large deltoid muscle to
further elevate the arm. In other words, without the rotator cuff, the
humeral head would ride up partially out of the glenoid fossa, lessening
the efficiency of the deltoid muscle.
The rotator cuff is a group of four muscles and their tendons that wrap around the front, back, and top of the shoulder joint. These let the shoulder function through a wide range of motions. Stress on the shoulder may cause them to tear, which can make routine activities difficult and painful.
The anterior and posterior
directions of the glenoid fossa are more susceptible to shear force
perturbations as the glenoid fossa is not as deep relative to the
superior and inferior directions.
The rotator cuff's contributions to
concavity compression and stability vary according to their stiffness
and the direction of the force they apply upon the joint.
Further Reading
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"Rotator cuff"
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