Median Brachial plexus

Injection of a local anesthetic into or around individual peripheral nerves or nerve plexuses produces even greater areas of anesthesia than do the techniques described above. Blockade of mixed peripheral nerves and nerve plexuses also usually anesthetizes somatic motor nerves, producing skeletal muscle relaxation, which is essential for some surgical procedures. The areas of sensory and motor block usually start several centimeters distal to the site of injection. Brachial plexus blocks are particularly useful for procedures on the upper extremity and shoulder. Intercostal nerve blocks are effective for anesthesia and relaxation of the anterior abdominal wall. Cervical plexus block is appropriate for surgery of the neck. Sciatic and femoral nerve blocks are useful for surgery distal to the knee. Other useful nerve blocks prior to surgical procedures include blocks of individual nerves at the wrist and at the ankle, blocks of individual nerves such as the median or ulnar at the elbow, and blocks of sensory cranial nerves. 

This case is a good example of multiple impingement syndromes. Besides the obvious carpal tunnel, A.M. had some additional impingement of the median nerve as it passes by the pronator teres. The tension in the soft tissues at the thoracic inlet impinged the nerves of the brachial plexus as they passed through the costoclavicular space. It is important to remember that when there is a fall on the rigid arm, the force is transmitted all the way to the neck. In A.M. s case,... 

Proceeding toward the interscalene area, the roots of C5 and C6 join together to form the upper trunk, the root of C7 emerges by itself as the intermediate trunk and, in the lower neck, the roots of C8 and Tl form the lower trunk of the plexus. More distally, in the supraclavicular region, each trunk gives off two divisional branches, named the anterior and posterior divisions, which innervate the flexor and extensor muscles of the upper extremity respectively. In the axilla, these divisions join in various combinations to form the cords of the brachial plexus. The relationship of the cords with the axillary artery determines their names the lateral, medial and posterior cords. The axillary and radial nerves originate from the posterior cord, the musculocutaneous and part of the median nerve arise from the lateral cord, vdiereas the other contribution of fibers to the median nerve and the ulnar nerve originate from the medial cord. 

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