Inferior Trunk of the Brachial Plexus, Gross Anatomy

Description

Arising from the ventral rami of C8 and T1, the inferior trunk of the brachial plexus is shown coursing in the lower posterior triangle of the neck as it converges superior to the first rib and just posterior to the clavicle. Anterior and middle scalene muscles form the interscalene interval where these roots emerge, while the clavicle lies anterior and inferior as a bony roof over the supraclavicular plexus. Nearby shoulder girdle landmarks, including the superior scapular region and overlying trapezius and deltoid, frame the plexus as it passes laterally toward the axilla. Relationships matter here. Clinically, the C8 to T1 contribution is the substrate for many lower plexus presentations, from true neurogenic thoracic outlet syndrome to traction injuries that selectively weaken intrinsic hand muscles and alter sensation along the medial forearm and ulnar hand. This is the segment most vulnerable to compression between a cervical rib or fibrous band and the first rib, and it sits close to the subclavian vessels, so correlating nerve position with adjacent blue-coded vasculature helps explain mixed neurovascular symptoms. Surgeons and anesthetists also care about its location when planning supraclavicular blocks, where needle trajectory must respect the plexus as it lies posterolateral to the subclavian artery and above the pleural dome. Use this artwork for teaching the organization of the brachial plexus in gross anatomy and neuroanatomy courses, for illustrating thoracic outlet syndrome mechanisms in clinical texts, or for orienting learners before supraclavicular exploration and regional anesthesia workshops. It also fits well in exam-prep materials that distinguish lower trunk deficits from ulnar neuropathy at the elbow or wrist. Anatomical accuracy verified by SciePro's Medical Advisory Board.