Anatomical Structure and Location of the Middle Trunk of the Brachial Plexus

Description

Arising from the anterior ramus of C7, the middle trunk of the brachial plexus is shown in the lateral neck as it joins the superior and inferior trunks within the interscalene interval. Anterior and middle scalene muscles form the muscular boundaries, with the trunks coursing inferiorly and laterally toward the supraclavicular fossa, deep to the sternocleidomastoid and omohyoid. Superiorly, the cervical spinal nerve root and dorsal root ganglion region align with the intervertebral foramen, while inferiorly the plexus approaches the first rib and clavicle on its way to reorganize around the axillary artery. Color coding separates red muscle planes, yellow neural elements, blue vessels, and green lymph nodes. For teaching and clinical orientation, this segment matters because the C7-derived middle trunk is a common contributor to sensory and motor deficits after traction injuries and is frequently referenced when localizing brachial plexopathy patterns. Needle placement for an interscalene block targets the roots and upper trunks between the scalene muscles, and spread to the C7 component helps explain anesthesia of the lateral shoulder and proximal upper limb, while sparing can leave patchy deficits. Small margins, high stakes. Close adjacency of the plexus to the subclavian vessels and regional lymphatics also underlines why supraclavicular masses, thoracic outlet anatomy, or postoperative scarring can produce mixed neurovascular symptoms. Use this artwork in gross anatomy lab manuals, neuroanatomy and regional anesthesia lectures, and surgical texts discussing supraclavicular exploration of the brachial plexus or neck dissection planes. It also fits well in patient-facing education for brachial plexus injury and perioperative block consent, where clear separation of muscles, nerves, vessels, and lymph nodes supports rapid spatial understanding. Anatomical accuracy verified by SciePro's Medical Advisory Board.