Formation of median nerve without the medial root of medial cord and associated variations of the brachial plexustrunk

Sharmila BHANU P, Devi SANKAR

Abstract

The anatomical variations in the formation, course and termination of brachial plexus are well documented and have clinical significance to surgeons, neurologists and anatomists. The present case report describes the unusual origin of median nerve, arising directly from the lateral cord without the union of lateral and medial roots of brachial plexus. A communicating branch existed between the ulnar nerve and anterior division of middle trunk. The lateral pectoral nerve was arising from anterior divisions of upper and middle trunks as two separate branches instead from lateral cord. The branches then joined together to form the lateral pectoral nerve. The medial cord instead of its five terminal branches, had only three branches, the ulnar nerve, medial pectoral nerve and a single trunk for the medial cutaneous nerve of arm and forearm which got separated at the middle of the arm. The variations of the lateral cord and its branches make it a complicated clinical and surgical approach which is discussed with the developmental background.