Shoulder Pain and the Infraspinatus
By David Kent
Shoulder Pain and the Infraspinatus
By David Kent
Patients with shoulder pain that inhibits them from combing their hair, brushing their teeth or reaching behind their back for their bra strap often can't sleep on the affected side. When these symptoms include deep anterior shoulder pain that extends down the front and side of the arm, the radial forearm and into the hand, the infraspinatus muscle could be involved. This article will provide useful information covering the anatomy, function, trigger point patterns and treatment tips for the infraspinatus muscle.
The infraspinatus is one of the four rotator cuff muscles. The supraspinatus, infraspinatus, teres minor and subscapularis are also referred to as the "SITS" muscles." The primary combined function of these four muscles is to hold the relatively large head of the humerus in the smaller, shallow, glenoid cavity of the scapula. The tendons of the muscles blend with the fibrous capsule of the glenohumeral joint to form a musculotendonous rotator cuff, which reinforces the capsule on three sides (anteriorly, superiorly, and posteriorly) as it provides active support for the glenohumeral joint."1
Portions of the infraspinatus muscle are covered by the trapezius and posterior deltoid. Medially the infraspinatus muscle attaches to the infraspinatus fossa of the scapula and to the adjacent fascia. Laterally it attaches to the middle facet on the greater tubercle of the humerus. (See Figure 1.)
The infraspinatus produces lateral rotation of the arm at the glenohumeral joint along with the teres minor and the posterior fibers of the deltoid muscle. The antagonistic muscles that produce medial rotation at the glenohumeral joint include the pectoralis major, anterior fibers of the deltoid, subscapularis, latissimus dorsi, and teres major.
As mentioned in the anatomy section, the infraspinatus also helps stabilize the head of the humerous in the glenoid cavity of the scapula. It is important to assess, treat, lengthen and strengthen, as appropriate, the synergistic and antagonistic muscles that cross over joint. A muscle movement chart is a quick reference tool that groups joints by body region and then lists the muscles creating each specific joint movement. It also shows the degrees of normal range-of-motion (ROM) for each joint. This information helps you immediately develop a comprehensive treatment plan with goals that include ROM and provides a list of muscles to target.
We live in the age of digital cameras and cell phones with cameras. We all know the saying "A picture is worth a thousand words." It only takes a few minutes to shoot postural photos of your patient, display the images on the screen of the device and show your patients how their posture is attributing to their pain and how you can help. (Read: "Tools to Succeed for Massage Therapists" MT May 2009.)
Using assessment tools likes a postural analysis chart and plumb line will guarantee your patient is positioned correctly and in same place to document improvement over a series of treatments. Another advantage of having the grid chart in the background of the photos is to help the untrained eye of your patients to easily see a high shoulder or forward head posture which again helps reinforce the stresses the muscles are enduring which can lead to the formation of trigger points. Include a "Free Posture Analysis: A $___ Savings" in your therapy package to set your practice apart from others in your area. (Read: "Getting Comfortable with Postural Analysis" MT July 2008.)
Patients are looking to you for answers explaining why they hurt. Besides postural photos, trigger-point charts are the perfect aid for educating your patients about referred pain from myofascial trigger points. This visual helps them immediately see the referred pain patterns for each muscle. A trigger-point and muscle-movement flip chart is the perfect traveling educational tool.
Show your patients how referred pain from trigger points located in the midportion of the infraspinatus muscle is reported as a deep anterior shoulder pain that extends down the ventral and lateral arm, the radial half of the forearm and into the hand. Pain may occasionally be referred into the suboccipital and posterior cervical region. (See Figure 2.)
TrPs near the vertebral border of the scapula may refer into the rhomboids. (See Figure 3.)
Include a variety of modalities and techniques in your treatment sessions. The below techniques are another way of treating myofascial trigger points.
Step 1 - Glide
The patient is in the prone position, their shoulder abducted to 90 degrees and the forearm hanging off the side of the therapy table. The therapist is standing at approximately the level of T12, facing the head. Lubricate and glide on the entire muscle in thumb-width strips, lateral to medial. (See Figure 4.)
Step 2 - Specific
Next, palpate for trigger points with fiber and cross fiber movements on the muscle. To prevent your hands from sliding on the patient's skin due to the use of lubrication, simply place a tissue or linen on the skin and work through it to perform the movement. This simple tip will prevent unnecessary stress and pain in your hands from working too hard. (See Figure 5.)
Step 3 - Scapular Spine
If you have received training in the proper use and handling of pressure bars you can find this tools helpful in treating the tissues immediately inferior to the spine of the scapulae. (See Figure 6.) Otherwise use your finger tips to treat this tissue.
Step 4 - "SIT" Tendons
Since the tendons merge to form a musculotendonous rotator cuff, we treat three of the four tendons from this position. Lubrication is only used during this step if sensitivity prevents specific work. The client's arm is on the table with their palm turned toward ceiling. (See Figure 7.) This properly positions and exposes the facets on the greater tubercle of the humerus for treatment. Palpate with the non-treating hand, the anterior and posterior aspect of the acromion process. Place the pad of the treating thumb halfway between the anterior and posterior aspect of the acromion process and immediately lateral to it. (See Figure 8.) This will place your treating thumb over tendon attachment of the supraspinatus on the superior facet with fiber and cross fiber movements, gently treat the tendon attachment. (See Figure 9.)
Next move your treating thumb immediately posterior one thumb-width placing it over the infraspinatus tendon as it attaches on the middle facet. (See Figure 10.) As before treat the tendon attachment. Next, reposition your treating thumb one more thumb-width posteriorly, placing it over the inferior facet to treat the tere minor tendon. (See Figure 11.)
Patients need to be educated in self-care that includes regular stretching and strengthening. Inform patients about the benefits of products like exercise balls and resistance bands they can use at home anytime to accommodate their busy schedules allowing them to workout and stretch.
Topical analgesics can also benefit your patients and practice. They provide both drug-free pain relief for your patients and additional income for your practice without you spending additional time performing treatments.
Listen carefully to your patients as they will share many clues about the origin of their pain while reporting their subjective complaints. Shoulder pain and restricted range-of-motion from the infraspinatus can interfere with many activities of daily living from interfering with sleep to prevent someone from combing their hair or brushing their teeth. Take a few minutes to assess, educate, treat and determine short- and long-term treatment goals with each patient.
Wishing you many successful treatment sessions.
- Moore KL, Dalley AF. Clinically Oriented Anatomy, 4th ed. Lippincott, Williams and Wilkins, 1999.