Shoulder Girdle and Rotator Cuff pain is extremely common and myofascial dysfunction is a common cause. Over 20 muscles refer pain to the shoulder and may also be the source of mysterious pain, tingling and/or weakness in arm, hand, or fingers. In the following illustrations, black dots indicate common trigger point locations; red areas indicate the pain referred by the trigger point. You can evaluate these muscles with the Rotator Cuff Tests excerpted and adapted from our Range-of-Motion Testing Charts. (See also cervical and head pain patterns and testing.)
Latissimus Dorsi. This powerful back muscle refers pain to the lower shoulder blade and to the front of the shoulder where it attaches. There may also be pain running along the medial side of the arm down to the ring and little fingers and / or pain in the side waist area. "Imaginary Lat Syndrome" (arms held out to the sides as if unable to fall naturally) is common in new weight lifters. Unfortunately, doing this strains the traps and shoulder girdle muscles. If not imaginary, and accompanied by the pain patterns shown here, lats may be chronically shortened and in need of stretching. Lat pain referred to the lower edge of the scapula is believed to create trapezius TrP3 which in turn creates other TrPs in the upper fibers. See Trapezius above.
Scalenes ("thoracic outlet" and "carpal tunnel" syndromes; chest, arm, and upper back pain). You may think you're having a heart attack. Get it checked! If no cardiac problems are found, consider other muscles, especially if you have tingly thumb or index fingers. Scalenes contribute to severe tension headache. They are one of the leading causes of "carpal tunnel syndrome." On the list of a half-dozen possible causes, the carpal tunnel itself is dead last. Check before you cut! In Aikido, new students tend to interpret kokyu-nagetechniques (actually based on timing and balance) as: "Swing your partner around by the neck then drop him on his head" -- an interesting variation on the game of “Hangman.” In the NFL, doing the same thing to a large, padded, extremely fit refrigerator-sized man by grabbing his face-guard is an instant 15-yard penalty.
The consequences of “neck-a-nage” can be extremely painful; the electrical supply for arm and fingers comes from the brachial plexus, the “wiring harness” originating in the neck. Pain may extend into chest, shoulder, the area between the shoulder blades and down the arm to the index finger and thumb. Where care and consideration have failed, know this pain pattern and what to do for it. A similar pattern arises from omohyoid, especially following flu and any condition that involves bouts of vomiting.
The Rotator Cuff Muscles
Supraspinatus (Rotator Cuff). Pain "above the spine of the scapula," strongest on outside of shoulder. It extends down the arm to the elbow and possibly along the lateral (thumb side) of the forearm. Commonly strained in association with infraspinatus.
Infraspinatus (Rotator Cuff). This muscle of the back is a very common source of pain on the lateral and front side of the shoulder. Pain is felt deep in the shoulder joint, primarily at the front of the shoulder. Pain may extend down lateral (thumb side) and anterior ("fishbelly") side of the arm as far as the front and back of the hand. Commonly injured in sudden abrupt arm movements such as catching oneself when falling backwards or excessive poling while skiing.
Problems reaching your hip pocket? Chances are that the problem is infraspinatus, possibly with a tight anterior deltoid. Infraspinatus is the major muscle of (and "below the spine of") the scapula.
Subscapularis (Rotator Cuff). This unfamiliar muscle is a critical member of the rotator cuff and a major player in the garbage-can diagnosis known as "frozen shoulder." Subscapularis lines the entire underside of the scapula, between scapula and rib cage, visible only in part via the arm pit. Pain extends over the scapular area, into the posterior shoulder (and possibly to the top of shoulder). It may be impossible or painful to raise the arm to comb hair. There may be pain down the underside (medial side) of arm perhaps with an odd bracelet of pain around the wrist and swelling on the back of the hand. See more here.
Teres Minor (Rotator Cuff). Refers "silver dollar pain" to the back of the arm, apparently deep in the posterior deltoid. It may refer pain up to the shoulder and numbness and tingling down to the fourth and fifth (ring and pinky) fingers. Teres minor rotates the arm laterally and is the smallest and most "minor" of the rotator cuff muscles working in concert with the infraspinatus.
Pain from this muscle is sharply localized, deep and, notes Travell and Simons, "about the size of a prune." The extremely localized nature of teres minor pain is one of its best diagnostic features. However, the teres muscles are two of the the least likely muscles to have pain and trigger points in healthy persons.
Check teres if pain and restriction remain after releasing the other rotator cuff muscles -- especially if the sufferer plays volleyball or tennis. The muscle is especially subject to strain when arms are extended high over and behind the head as in serving a tennis ball or performing or blocking a spike in volleyball.
Like so many other back and shoulder muscles, teres minor is strained by tight pectoralis (chest) muscles. See Pectoralis Major and Minor below.
Teres Major. Pain to the shoulder over the region of the posterior deltoid.
Deltoids. One of the few muscles that actually hurts at the source!. Pain may radiate down the arm as far as the elbow, but the pain pattern is uncommonly local. Anterior deltoid hurts in the front of the shoulder (with some spillover pain to side and back). It restricts reach to the back. Posterior deltoid hurts in the back of the shoulder (with some spillover pain to side and front). It restricts reach across the front of the body. Deltoids may develop satellite TrPs due to pain referral from other muscles as seen above. The flip side of saying deltoid pain is "local" is, once again, that pain in the deltoids may be coming from somewhere other than the deltoids.
Pectoralis Major Pectoralis major is the “major muscle of the chest.” The shoulder, arm, and chest pain of this muscle suggest serious disease. In women, breast pain is feared to be due to breast cancer and patients may be sent for repeated mammograms (ironically, exposing them to additional radiation). Tight pectorals can also cause shoulder and chest pain extending down the arm to below the elbow. In both men and women, this pattern (especially when on the left side) can be terrifyingly similar to the pain of angina and heart attack. Pectoralis major is strained or shortened by: Hunching shoulders forward, sitting or sleeping with arms crossed on chest, typing / keyboarding, sword work.
Conversely, pectoralis major can develop painful TrPs following a heart attack. Pain reflexes can shrink blood vessels, further starving the heart of blood. There is even a pectoralis TrP that causes irregular heartbeat.
Pectoralis Minor A leading cause of Thoracic Outlet Syndrome and Carpal Tunnel Syndrome due to entrapment of the brachial plexus and blood supply to the arm. Pain over the chest, anterior shoulder, extending down the arm medial side (pinky side) of arm as far as the last three (pinky, ring, and middle) fingers.
Serratus Posterior Superior. Another unfamiliar muscle which causes enormous amounts of pain. Pain concentrates over the upper half of the scapula spilling over into the middle back between scapula and spine. It extends to the posterior side of arm and shoulder, down the back of the arm to the elbow and from there to the back of the hand and lateral palm to the little finger. There may also be pain in the chest and anterior arm.
Coracobrachialis The TrP is in the shoulder at the coracoid process of the scapula (for which it is named). You'll get some severe pain there, but the pain also hops, skips, and jumps down the posterior arm (missing the elbow) as far as the back of the hand and the middle finger.
Biceps Brachii You would think that this powerful muscle would produce a similarly powerful pain pattern but it is, in fact, fairly localized. TrPs in the muscle belly extend pain down to attachments at elbow and shoulder.
Brachialis. Known as "the workhorse of the elbow," this muscle produces a weaker version of the Biceps pain pattern with an interesting twist. The main pain is felt in the fleshy portion of the base of the thumb.
Triceps Brachii A major player in tennis elbow, but a source of shoulder pain as well. Pain in posterior shoulder extending as far up as the angle of the neck, down the back and front of the arm and forearm. One of the three heads also entraps the radial nerve causing slowed nerve conduction, numbness and tingling in the two medial (pinky and ring) fingers.
Levator scapula (Wry neck). This muscle is the number one cause of "stiff" or "wry" neck and the second most common shoulder girdle muscle (trapezius is Number One) to have trigger points. Working with trapezius, levator shrugs the shoulders and helps prevent forward flexion of the neck, hence it is also damaged in whiplash injuries. It is commonly strained when shoulder (or shoulders) are chronically hunched, either in stress, or by attempting to keep a strap from sliding off the shoulder, especially when muscle is cold or fatigued.
Omohyoid (Head, neck, shoulder, and back pain). This peculiar muscle, which doesn't even show up in a lot of anatomy books can cause disabling pain and dysfunction. It's another one of the muscles that attaches to the hyoid bone but the other end attaches to the scapula. Aside from the pain (which often appears after a bout of coughing or vomiting) there may also be weakness and tingling down arm and fingers (similar to the scalene pattern) and symptoms of thoracic outlet syndrome.
Rhomboids Not exactly shoulder pain, but certainly related. Rhomboid pain is fairly localized, appearing between the shoulder blades, the place where everyone loves a backrub. Pain may extend out across the top of the scapula towards (but not up to) the neck. Again, local pain, but commonly fired off as satellites of pain patterns from other muscles, especially the scalene muscles of the neck, serratus posterior superior, and levator scapula.
Subclavius This odd little muscle depresses and stabilizes the clavicle (collarbone). It also refers pain locally to the front of the clavicle and anterior shoulder, down the anterior arm along the biceps and the lateral (thumb) side of the arm as far as the thumb, index, and middle fingers. Another referral patten that may be mistaken for Carpal Tunnel Syndrome.