Medial Cord of the Brachial Plexus, Anterior View

Description

Emerging from the anterior divisions of the inferior trunk, the medial cord (fasciculus medialis) lies medial to the axillary artery in the infraclavicular region and continues into the proximal axilla. From this cord, the ulnar nerve descends on the medial side of the arm, while the medial root of the median nerve runs anterior to the artery to join the lateral root and form the median nerve. A critical landmark. Surrounding skeletal references in this anterior shoulder and upper thorax view logically include the clavicle superiorly, the scapula laterally and posteriorly, the proximal humerus at the glenohumeral joint, and the adjacent ribs forming the thoracic cage. Anterior orientation matters here because it mirrors how you encounter the plexus in infraclavicular exposure and axillary surgery, where cords are named by their relationship to the second part of the axillary artery rather than by spinal level. The medial cord and its branches are at risk during axillary lymph node dissection and breast surgery, and traction or compression in the axilla can present with ulnar-distribution sensory loss and intrinsic hand weakness, or with mixed median nerve findings once the median roots have united. Understanding where the medial root crosses to meet the lateral root helps explain variable clinical patterns when lesions occur near the artery. Use this asset in gross anatomy teaching of the brachial plexus cords, in operative anatomy chapters covering infraclavicular and axillary approaches, and in clinical education materials on lower plexus injury patterns and peripheral nerve deficits of the upper limb. It also reads cleanly in exam-prep diagrams where the goal is to connect cord-level anatomy to the ulnar and median nerves without distracting posterior structures. Anatomical accuracy verified by SciePro's Medical Advisory Board.