Two Trunked Brachial Plexus: Multiple Variations in Formation, Course and Distribution

Abstract

Brachial plexus is a very complicated nerve network of upper limb. Many anatomical variations have been documented regarding its formation, course and distribution. Understanding of variations in brachial plexus is very important for clinicians, especially during surgical approach of axilla and neck region. Multiple variations in the left brachial plexus of about 70-year-old male cadaver, during routine dissection classes of upper extremities was noted in this variation of brachial plexus in which the middle trunk was absent. Other associated anomalies of same plexus were- all the three cords and their branches lie lateral to the axillary artery. Coracobrachialis was supplied by more than one branch of lateral cord. A loop was formed by joining of medial as well as lateral pectoral nerve around superior thoracic artery and there was also a connection present between lateral and medial root of median nerve. Therefore, the purpose of this paper was to unfold the complexity of brachial plexus. These changes may or may not affect the functioning of upper extremity of this person, but the knowledge of these variations are necessary during the surgical procedures as well as to evaluate unexplained sensory or motor loss after trauma. It also helps the clinicians for proper understanding of some previously unexplained clinical symptoms.

Keywords

• axillary artery
• brachial plexus
• coracobrachialis
• median nerve
• single cord
• superior thoracic artery