A ligament called the ligament of Struthers is present in 1 percent to 3 percent of the population. This location is only a possible source of nerve entrapment in a small percentage of the population. Moving distally after leaving the axillary region, the next location where median nerve entrapment is likely, is just proximal to the elbow. Other thoracic outlet syndrome variations that may compress the median nerve include the region between the anterior and middle scalene muscles, between the clavicle and first rib, and underneath the pectoralis minor muscle. This is called true neurological thoracic outlet syndrome. Fibers of the median nerve can get compressed against a pathological bony extension of the C7 transverse process, called a cervical rib. Thoracic outlet syndrome is not consistently defined in the medical literature, so there is a great deal of confusion about it. Since the nerve roots also contain fibers for other peripheral nerves, symptoms of compression at the nerve root level may extend outside the commonly mapped area for median nerve sensory involvement illustrated in Figure 1.Īfter leaving the cervical region, the next several locations of potential entrapment are all part of what is commonly called thoracic outlet syndrome. Intervertebral discs, bone spurs, small tumors, or other obstructions may press on these nerve roots and produce symptoms that affect the median nerve. The median nerve is derived from the C5-T1 nerve roots. The first location where median nerve compression may occur is at the cervical nerve roots. Motor problems from median nerve compression usually show up as weakness in grip strength or atrophy of the thenar eminence (fleshy part of the palm near the base of the thumb). The median nerve and its branches innervate primarily the flexors of the wrist and fingers, as well as several muscles of the thumb. They include pain (often described as sharp, shooting, or electrical in nature), paresthesia ("pins and needles"sensations), and numbness. The sensory symptoms are located primarily in the palm (See Figure 1). Therefore, compression of the nerve may create both sensory and motor deficit. The median nerve carries both motor and sensory fibers. It is essential to thoroughly evaluate the problem before coming to a conclusion about the presence of the ever-popular CTS. We will follow the nerve's course from the spinal cord to its termination in the hand and describe common locations of compression pathology. This article will look at the entire length of the median nerve where there are numerous locations that median nerve entrapment may occur. Because this condition is studied so often, we have a very good understanding of how it occurs however, because it has become such a "popular" condition, clinical practitioners may be too eager to assume the presence of CTS simply because their patient/client experiences median nerve compression symptoms. CTS involves compression of the median nerve at the base of the hand in a region called the carpal tunnel. The most researched and well-defined upper extremity nerve-entrapment problem is carpal tunnel syndrome (CTS).
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