Posterior triangle of the neck
|Posterior triangle of the neck|
Side of neck, showing chief surface markings. (Nerves are yellow, arteries are red.)
|Latin||regio cervicalis lateralis, trigonum cervicale posterius|
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The posterior triangle (or lateral cervical region) is a region of the neck.
It has the following boundaries:
Anterior: Posterior border of the sternocleidomastoideus
Posterior: Anterior border of the trapezius
Base: Middle one third of the clavicle
Roof: Investing layer of the deep cervical fascia
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:
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)
- Subclavian artery (Third part)
- Transverse cervical artery
- Suprascapular artery
- Terminal part of external jugular vein
C) Lymph Nodes:
- Inferior belly of omohyoid muscle
- Anterior Scalene
- Middle Scalene
- Posterior Scalene
- Levator Scapulae Muscle
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 (e.g., for brushing hair), particularly due to compromised trapezius muscle innervation.
The right atrial pressure is reflected in it because there are no valve in the entire course of this vein and is straight, therefore used to examine Jugular Venous Pressure.
As external jugular vein pierces the fascia, the margins of the vein get adherent to fascia. So if the vein gets cut, it cannot close and air is sucked in due to negative intrathoracic pressure causes air embolism. To prevent this, fascia colli has to be cut.
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- 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."