c) Shoulder, Upper Back and Upper Arm

Never assume the root cause of a problem is at the place that hurts!

Muscles whose trigger points cause shoulder, upper arm, and upper back pain can be divided into five groups : scalenes, shoulder blade suspension muscles, rotator cuff muscles, upper arm muscles, and spinal muscles.

Although the scalenes are neck muscles, their trigger points cause a surprising amount of pain in the upper back, shoulder, and upper arm. Scalenes trigger points also contribute significantly to pain and other symptoms in the forearm and hand. The scalenes are so important that they should always come first in troubleshooting pain in all these areas.

The shoulder blade suspension muscles are the rhomboids, levator scapulae, and trapezius. They suspend the shoulder blade from the spinal column and their function is to help move the shoulder blade into position for all actions of the arm and hand. Their trigger points send pain to the upper back and neck, referring only a minor amount to the the shoulder…

The four rotator cuff muscles are the supraspinatus, infraspinatus, teres minor, and subscapularis. They attach the shoulder blade to the top of the humerus, the upper arm bone. They rotate the arm and keep the shoulder joint together. Trigger points in the rotator cuff muscles cause a major portion of the pain in the shoulder, along with the clicks and grinding noises and loss of mobility. They’re indirectly responsible for physical deterioration of the shoulder joint and can predispose it to serious physical injury, including rotator cuff tears and dislocation (Travell and Simons, 1999, 538-571, 596-607).

Muscles that move the upper arm include the deltoids, teres major, latissimus dorsi, coracobrachialis, biceps, and triceps. Only the last three are actually part of the arm. In addition to pain in the shoulder, back, and upper arm, trigger points in these muscles can send pain to the forearm, hand, and fingers.

The spinal muscles interconnect the vertebrae and have no direct connection to the shoulder… they’re a common source of upper back pain…

Source : Clair Davies, The Trigger Point Therapy Workbook, p.79.