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C h e c k o u t A B M P 's l a t e s t n e w s a n d b l o g p o s t s . Av a i l a b l e a t w w w. a b m p . c o m . 87 After passing the supraspinatus region, the nerve makes a sharp bend as it curves around the spinoglenoid notch (Image 3). Where the nerve bends around the rigid bony border of the spinoglenoid notch, it is vulnerable to compression. In almost half the population, there is a connective tissue band called the spinoglenoid ligament that forms a second narrow tunnel where the nerve must pass (Image 3). 3 This ligament is also designated in some resources as the inferior transverse scapular ligament. Some anatomical references show this small ligament covering the suprascapular nerve farther along its path away from the spinoglenoid notch (Image 3). Because these small ligaments do not appear in all individuals, it is possible there may be multiple locations where these anatomical anomalies occur. Regardless of their location, the impact on compressing the suprascapular nerve is similar in both situations. PATHOPHYSIOLOGY AND ETIOLOGY The suprascapular nerve has very little room for additional movement as it passes by these anatomical obstacles. Nerves must be somewhat mobile and able to slide relative to adjacent structures. Some scapular movements put significant tensile (pulling) stress on the suprascapular nerve and may lead to nerve pathology. Protraction and abduction both pull the nerve against rigid bony borders and may cause neural tension or compression. Elevation and rotation of the arm can also put traction forces on the nerve because of the movement of adjacent muscles that pull on nerve fibers. A number of shoulder pathologies, such as fractures of the clavicle or scapula, soft-tissue cysts or masses, or soft-tissue injuries like rotator cuff tears, can also lead to suprascapular nerve compression. Sometimes these shoulder injuries distort the pathway of the nerve, causing neural compression or tension. Frequent overhead work, or any positions that involve repeated abduction and external rotation, put the nerve in a vulnerable position. Suprascapular neuropathy is common in many sporting activities. It is reported with frequency in volleyball players because of the vigorous overhead motions with the dominant hand during volleyball play. 4 Suprascapular neuropathy can also cause other shoulder problems from biomechanical dysfunction. Nerve compression may cause atrophy of supraspinatus and infraspinatus muscles, which then causes dysfunctional mechanics of the rotator cuff. For example, the infraspinatus and teres minor muscles play a major role in decelerating momentum of the arm at the end of a throwing motion. If the infraspinatus is weak due to nerve compression, it can't generate the same eccentric force to decelerate the arm. Weakness of the posterior rotator cuff complex can lead to tendinosis in the affected tendons. When these muscles are weak, more of the deceleration forces transfer to the joint capsule tissues, and that may stress these capsular tissues. Muscular atrophy and weakness is a primary symptom from suprascapular neuropathy. However, motor symptoms do not occur in isolation because there are also sensory fibers within the suprascapular nerve. Impaired sensory signals that may occur from suprascapular neuropathy include increased shoulder pain in the posterior or lateral shoulder region. There may also be tingling, numbness, or other altered sensory sensations in the region. IDENTIFYING NERVE COMPRESSION It is challenging to identify suprascapular neuropathy because its symptoms are similar to many other shoulder complaints. For example, people may report lateral shoulder pain along with difficulty bringing the shoulder into abduction. It is common for this pattern to be diagnosed as rotator cuff pathology or subacromial bursitis without a thorough exploration of other possible causes. These same symptoms could be attributed to suprascapular neuropathy. Difficulty abducting the arm occurs because the supraspinatus muscle, which is essential for abduction, is not getting adequate motor signals. Posterior and lateral shoulder pain occurs as the nerve gets further stretched during the motion of abduction. Key factors to look for in the client history include long periods of holding the shoulder in abduction or significant repetitive motion where the shoulder is brought into abduction or protraction numerous times. Pain, usually described as sharp, will generally accompany that position. Observation of the posterior shoulder region may give helpful clues in more advanced stages of the condition. Infraspinatus atrophy that occurs from suprascapular nerve compression is often invisible, because there are few other muscles overlying it. Infraspinatus atrophy may appear as a slightly hollowed out depression on the posterior aspect of the shoulder, right over the infraspinous fossa. 3 The spinoglenoid notch and spinoglenoid ligament. Image is from 3D4Medical's Complete Anatomy application. Variations in the spinoglenoid location