Answer:
Starting at the spinal cord, the subdivisions of the brachial plexus are (in order): roots, trunks, divisions, and cords.
Explanation:
The brachial plexus is a nervous network that is located at the base of the neck, and connects the spinal cord to all peripheral nerves in the arm. It is composed of five spinal roots (C5, C6, C7, C8 and T1) that join, forming three primary trunks: the upper trunk, which comes from the anterior branches of nerves C5 and C6, the middle trunk, comes from the anterior branch of nerve C7 and the lower trunk: it comes from the anterior branches of nerves C8 and T1. Once the clavicle is passed, each trunk is divided into an anterior and a posterior division, which will be reorganized to form the secondary trunks, fascicles or cords. The set of the posterior branches forms the posterior cord. The union of the anterior branches of the upper and middle trunk forms the lateral cord and the anterior branch of the lower trunk gives rise to the medial cord.
