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Posterior triangle of the neck
Posterior triangle of the neck
	Posterior triangle
	Side of neck, showing chief surface markings. (Nerves are yellow, arteries are red.)
Details
Identifiers
Latin	trigonum cervicale posterius; trigonum colli posterius; regio cervicalis posterior
TA98	A01.2.02.009
TA2	239
FMA	57778
	Anatomical terminology [edit on Wikidata]

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

Boundaries

The posterior triangle has the following boundaries:^[1]

Apex: Union of the sternocleidomastoid and the trapezius muscles at the superior nuchal line of the occipital bone

Anteriorly: Posterior border of the sternocleidomastoideus

Posteriorly: Anterior border of the trapezius

Inferiorly: Middle one third of the clavicle

Roof: Investing layer of the deep cervical fascia

Floor: (From superior to inferior)

1) M. semispinalis capitis

2) M. splenius capitis

3) M. levator scapulae

4) M. scalenus posterior

5) M. scalenus medius

Divisions

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

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

Clinical significance

The accessory nerve (CN XI) is particularly vulnerable to damage during lymph node biopsy. Damage results in an inability to shrug the shoulders or raise the arm above the head, particularly due to compromised trapezius muscle innervation.

The external jugular vein's superficial location within the posterior triangle also makes it vulnerable to injury.

References

This article incorporates text in the public domain from page 563 of the 20th edition of Gray's Anatomy (1918)

^ Casale, Jarett; Geiger, Zachary (2022), "Anatomy, Head and Neck, Posterior Neck Triangle", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30725974, retrieved 2023-01-19

External links

lesson5 at The Anatomy Lesson by Wesley Norman (Georgetown University) (necktriangle)
lesson6 at The Anatomy Lesson by Wesley Norman (Georgetown University)
Anatomy figure: 24:01-02 at Human Anatomy Online, SUNY Downstate Medical Center - "Identification of the muscles associated with the posterolateral triangle."