Overview
This lecture introduces the major anatomical landmarks and dissection steps for studying the posterior triangle of the neck, focusing on boundaries, contents, and related structures.
Posterior Triangle of the Neck: Overview
- The posterior triangle of the neck is a key anatomic region located in the lateral cervical region.
- It is bounded anteriorly by the sternocleidomastoid muscle, posteriorly by the trapezius muscle, and inferiorly by the clavicle.
- The triangle is subdivided by the inferior belly of the omohyoid muscle into the occipital and supraclavicular (subclavian) triangles.
Major Contents and Structures
- Key nerves found in this area include the spinal accessory nerve (cranial nerve XI), roots and trunks of the brachial plexus, and branches of the cervical plexus.
- The external jugular vein crosses the sternocleidomastoid and drains into the subclavian vein.
- Major arteries include the transverse cervical and suprascapular arteries, branches of the thyrocervical trunk.
- The triangle also contains lymph nodes and portions of the scalene muscles (anterior, middle, and posterior).
Muscles Associated with the Triangle
- The floor is formed by muscles: splenius capitis, levator scapulae, and the anterior, middle, and posterior scalene muscles.
- The omohyoid muscle helps divide the triangle into its smaller subregions.
Dissection Tips
- Identify and preserve important neurovascular structures, especially the spinal accessory nerve and brachial plexus roots.
- Recognize the relationship between the scalene muscles and the subclavian artery and vein.
- Carefully trace the external jugular vein and its connections.
Key Terms & Definitions
- Posterior Triangle — a region on the side of the neck defined by the sternocleidomastoid, trapezius, and clavicle.
- Sternocleidomastoid — muscle forming the anterior border of the triangle.
- Trapezius — muscle forming the posterior border.
- Brachial Plexus — network of nerves supplying the upper limb, visible in the triangle.
- Cervical Plexus — network of nerves supplying the neck and upper shoulder.
- Spinal Accessory Nerve (CN XI) — cranial nerve that innervates sternocleidomastoid and trapezius muscles.
Action Items / Next Steps
- Download and review the "Posterior Triangle of the Neck" dissection worksheet PDF.
- Prepare for lab by identifying boundaries and contents of the posterior triangle on anatomical models or diagrams.
- Study the course and clinical importance of the spinal accessory nerve and brachial plexus in this region.