By Rob Parker, Physical Therapist
The rotator cuff is a group of four muscles and their tendons that connect the shoulder blade (scapula) to the top of upper arm bone (humerus.)
At the point of attachment on the arm, these four muscles form a "cuff" that reaches over the top of the arm bone and pulls it into its soft-tissue socket (the glenohumeral joint.)
In addition to other duties, the four muscles in this cuff help with the rotation of the arm, thus the name "rotator cuff."
We frequently hear about the rotator cuff because it is one of the most commonly injured structures in the shoulder. Its muscles are relatively small, and they are active in a very mobile joint through which substantial forces can be generated.
Because rotator cuff muscles thread themselves up and under the bone which forms curved top of the shoulder (the acromion,) they are vulnerable to abrasion and tearing from above. Anyone who does repetitive overhead lifting or throwing can attest to this sensation of pinching (impingement syndrome) which occurs when the muscles of the rotator cuff rub up against this bony hood (the acromion process) at the top of the shoulder.
In extreme cases, usually due to repetitive stress or trauma, the acromion can cut completely through one or more off the rotator cuff's tendons, the soft tissue that attach muscle to bone. This is called a rotator cuff tear, and occurs in various degrees of severity. Rotator cuff tears are often surgically repaired and then rehabilitated with physical therapy.
In less severe cases, the rotator cuff and its associated muscles can be therapeutically strengthened to pull their soft-tissue down and out of harm's way.
Rob Parker, PT, OCS, MS, ACT, COMT
Physical Therapist Rob Parker is medical advisor to Therapeutic Dimensions Inc.