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Posterior triangle of the neck
	Posterior triangle
	Side of neck, showing chief surface markings. (Nerves are yellow, arteries are red.)
Latin	regio cervicalis lateralis, trigonum cervicale posterius
Gray's	subject #145 563

The posterior triangle (or lateral cervical region) is a region of the neck.

[edit] Boundaries

It has the following boundaries:

	its apex union of the Sternocleidomastoid and the Trapezius muscles at the superior nuchal line of the occipital bone
anteriorly the posterior border of the Sternocleidomastoideus		posteriorly the anterior border of the Trapezius
	its base the distal (intermediate) one third of the clavicle

[edit] Divisions

The posterior triangle is crossed, about 2.5 cm above the clavicle, by the inferior belly of the Omohyoideus, which divides the space into two triangles:

an upper or occipital triangle
a lower or subclavian triangle (or supraclavicular triangle)

[edit] Contents

A) Nerves and Plexuses:

Spinal accessory nerve (Cranial Nerve XI)
Branches of cervical plexus
Roots and trunks of brachial plexus
Phrenic nerve (C3,4,5)

B) Vessels:

C) Lymph Nodes:

Occipital
Supraclavicular

D) Muscles:

Inferior belly of omohyoid muscle

[edit] Clinical significance

The Accessory Nerve (CN XI) is particularly vulnerable to damage at lymph node biopsy, where damage results in an inability to shrug the shoulders or raise the arm above the head (eg, for brushing hair).

The external jugular vein's superficial location also makes it vulnerable to injury.

[edit] Gallery

Sternocleidomastoid muscle

Muscles of the neck. Anterior view.

Posterior triangle of the neck labeled. (Anterior triangles to the left. Occipital triangle labeled at center left.) )

[edit] See also

Anterior triangle of the neck

[edit] External links

lesson5 at The Anatomy Lesson by Wesley Norman (Georgetown University) (necktriangle)
lesson6 at The Anatomy Lesson by Wesley Norman (Georgetown University)
SUNY Figs 24:01-02 - "Identification of the muscles associated with the posterolateral triangle."
lateral+cervical+region at eMedicine Dictionary

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.