Quick Facts
Origin: C5 and C6 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: Suprascapular nerve, anterior division of the superior trunk, posterior division of the superior trunk.
Supply: Sensory and motor innervation. Supplies the nerves branching off the lateral and posterior cords. Sensory to the posterior and lateral arm, forearm, and hand. Motor to the muscles of the posterior compartment of the arm and forearm, most flexors of the forearm, thenar muscles, and posterior axillary muscles.
Related parts of the anatomy
Origin
The superior trunk of the brachial plexus originates as the fifth and sixth cervical roots of the brachial plexus merge.
Course
The superior trunk of the brachial plexus originates in the neck, lateral to the fifth and sixth cervical 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 superior trunk continues posterior and inferior to the inferior belly of the omohyoid muscle. The superior trunk ends roughly at the midclavicular line, posterior to the clavicle where it splits into divisions.
Branches
The superior trunk of the brachial plexus gives rise to one nerve and two divisions. The suprascapular nerve originates on the superior trunk and is typically the only nerve to branch off a trunk of the brachial plexus. In a variation, the nerve to subclavius muscle is sometimes considered a branch of the superior trunk.
The superior trunk ends when it splits into the anterior and posterior divisions of the superior trunk. These contribute to the lateral and posterior cords and the nerves that arise from them.
Supplied Structures
The superior trunk supplies both sensory and motor innervation. It supplies motor innervation to the infraspinatus and supraspinatus muscles directly through the suprascapular nerve.
Other targets are indirect as the fibers of the superior trunk first pass through anterior and posterior divisions, then into lateral and posterior cords, respectively, before traveling out through nerves and terminal branches to their target tissues.
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Brachial Plexus
Neonatal brachial plexus palsy (NBPP) can be defined as a flaccid paresis of an upper extremity due to traumatic stretching of the brachial plexus, with the passive range of motion greater than the active.
