An often overlooked source of shoulder pain is the teres major muscle. The muscle connects the scapula to the upper arm and when shortened internally rotates the arm and pulls it closer to the side. It is not technically part of the rotator cuff but works together with those muscles to move and stabilize the arm.
Activities that require a person to keep their arm by their side and rotate the arm and hand in can cause this muscle to become shortened. Using a computer or texting for an extended time , writing for long periods or unbalanced physical training may lead to shortening of this muscle. The teres major may become spastic and pull the head of the arm into the socket improperly which leads to deterioration of the shoulder joint as well as stress to the other muscles.
Activities which require reaching higher than shoulder level require that teres major to be flexible and if it has become shortened, pain and clicking may be noticed in the shoulder joint. Tenderness of the teres major muscle is rarely reported but f often found upon examination. Patients with a shortened teres major muscle usually complain of pain in the shoulder, neck and mid back.
The teres major muscle is controlled by the subscapular nerve which is a division of another nerve which exits the spinal cord of the lower neck.Irritation of these nerves can alter the communication with muscles in this region resulting in dysfunction. Frequently, dysfunction of other muscles in the upper arm and neck accompany teres major shortening.
Treatment for shoulder pain must target shortened muscles, muscle imbalances, nerve irritation and joint wear.
High Power Laser Therapy is used to reduce the irritation of the nerve and muscles and to reduce the pain.
Manual mobilization of the teres major muscles, cervical spine and other shoulder muscles is performed in order to reduce muscle shortening and adhesions, and to restore proper movement.
Proper posture and movement education needs to be introduced in order to reduce future flare ups and slow degeneration of the shoulder.
David DeFries, D.C.