Quick Facts
Origin: C8 and T1 roots of the brachial plexus.
Course: In the neck, running laterally between the anterior and middle scalene muscles, through the posterior triangle towards the clavicle.
Branches: Anterior division of the inferior trunk, posterior division of the inferior trunk.
Supply: Sensory and motor innervation. Supplies the nerves branching off the medial cord, as well as the thoracodorsal and radial nerves of the posterior cord. Sensory to the posterior arm, forearm, and entire hand. Motor to the triceps brachii, and all the muscles of the forearm and hand. Motor to the latissimus dorsi.
Related parts of the anatomy
Origin
The inferior trunk of the brachial plexus originates as the merger of the eighth cervical and first thoracic roots of the brachial plexus.
Course
The inferior trunk of the brachial plexus originates in the neck, lateral to the upper thoracic vertebrae, roughly where the plexus reaches the scalene muscles. It runs laterally passing between the anterior and middle scalene muscles and into the posterior triangle of the neck. The inferior trunk continues posterior and inferior to the inferior belly of the omohyoid muscle. The middle trunk ends roughly at the midclavicular line, posterior to the clavicle where it splits into divisions.
Branches
The inferior trunk of the brachial plexus does not give rise to any nerves.
The inferior trunk ends when it splits into the anterior and posterior divisions of the inferior trunk. These contribute to the medial and posterior cords and the nerves that arise from them.
Supplied Structures
The inferior trunk supplies both sensory and motor innervation.
Targets are indirect as the fibers of the inferior trunk first pass through anterior and posterior divisions, then into medial and posterior cords, respectively, before traveling out through nerves and terminal branches to their target tissues.
