Posterior Triangle Anatomy

Overview

This lecture introduces the dissection steps and major anatomical structures found in the posterior triangle of the neck.

The posterior triangle is a key anatomical region on the lateral side of the neck.
It is bordered by the sternocleidomastoid muscle, trapezius muscle, and clavicle.
The triangle is important for containing major nerves, vessels, and muscles.

The triangle contains the spinal accessory nerve (cranial nerve XI), external jugular vein, and lymph nodes.
The brachial plexus roots pass through the posterior triangle.
The cervical plexus and phrenic nerve can be identified in this region.
Major arteries present include the subclavian, transverse cervical, and suprascapular arteries.
Muscles in the area include anterior, middle, and posterior scalene, levator scapulae, omohyoid (inferior belly), and splenius.

Dissection begins by reflecting skin and superficial fascia to expose the triangle’s boundaries.
Locate and identify major nerves, vessels, and muscles within the triangle.
Carefully follow and clean the course of the spinal accessory nerve and roots of the brachial plexus.
Examine and differentiate between scalene muscles.
Observe the relations of the omohyoid muscle and accompanying vessels.

Posterior Triangle of the Neck — Lateral neck region bordered by sternocleidomastoid, trapezius, and clavicle.
Brachial Plexus — Nerve network supplying the upper limb, with roots passing through the posterior triangle.
Spinal Accessory Nerve — Cranial nerve XI innervates the sternocleidomastoid and trapezius muscles.
Scalene Muscles — Group of three muscles (anterior, middle, posterior) important for neck movement and as anatomical landmarks.