Lateral Perspective of the Superior Trunk of the Brachial Plexus

Description

Emerging between the anterior and middle scalene muscles, the C5 and C6 ventral rami converge to form the superior trunk of the brachial plexus, rendered in yellow against the lateral neck. From this trunk, the suprascapular nerve and nerve to subclavius branch laterally and inferiorly toward the posterior triangle and clavicular region, while the trunk itself courses inferolaterally toward the costoclavicular space. Superficial and anterior to the plexus lie the sternocleidomastoid and infrahyoid strap muscles, with the clavicle and upper ribs forming an inferior boundary; the subclavian artery tracks nearby as a key relationship for orientation. Green lymph nodes and adjacent thyroidal tissue sit anteromedially, adding realistic surgical context. A lateral perspective matters because it mirrors how the plexus is encountered during supraclavicular exposure and regional anesthesia. The superior trunk is the structure most associated with Erb-Duchenne palsy, where traction injury at C5 to C6 produces weakness of shoulder abduction and external rotation via involvement of suprascapular and axillary nerve territories. This is a tight corridor. Scalene hypertrophy, fibrous bands, or post-traumatic callus near the clavicle can also distort the relationships that guide safe needle placement and dissection around the subclavian vessels. Use this artwork in gross anatomy and neuroanatomy teaching to clarify how roots transition into trunks and why the superior trunk sits where it does relative to the scalenes and clavicle. It also fits anesthesiology references on supraclavicular and interscalene blocks, and surgical texts covering thoracic outlet syndrome decompression, brachial plexus exploration, or lymph node biopsy in the posterior triangle. Anatomical accuracy verified by SciePro's Medical Advisory Board.