Posterior Triangle of the neck Flashcards
where is the posterior triangle of the neck
lateral aspect of the neck
boundaries of the posterior triangle of the neck
Its boundaries are as follows:
Anterior – posterior border of the SCM.
Posterior – anterior border of the trapezius muscle.
Inferior – middle 1/3 of the clavicle.
The posterior triangle of the neck is covered by the investing layer of fascia, and the floor is formed by the prevertebral fascia (see fascial layers of the neck).
muscle contents of the posterior triangle
The posterior triangle of the neck contains many muscles, which make up the borders and the floor of the area.
A significant muscle in the posterior triangle region is the omohyoid muscle. It is split into two bellies by a tendon. The inferior belly crosses the posterior triangle, travelling in an supero-medial direction, and splitting the triangle into two. The muscle then crosses underneath the SCM to enter the anterior triangle of the neck.
A number of vertebral muscles (covered by prevertebral fascia) form the floor of the posterior triangle:
Splenius capitis
Levator scapulae
Anterior, middle and posterior scalenes
vasular conents of the anterior triangle
The external jugular vein is one of the major veins of the neck region. Formed by the retromandibular and posterior auricular veins, it lies superficially, entering the posterior triangle after crossing the sternocleidomastoid muscle. Within the posterior triangle, the external jugular vein pierces the investing layer of fascia and empties into the subclavian vein.
The subclavian vein is often used as a point of access to the venous system, via a central catheter.
The transverse cervical and suprascapular veins also lie in the posterior triangle
The subclavian, transverse cervical and suprascapular veins are accompanied by their respective arteries in the posterior triangle.
The distal part of the subclavian artery can be located as it emerges between the anterior and middle scalene muscles. As it crosses the first rib, it becomes the axillary artery, which goes onto supply the upper limb.
nerve contents of the posterior triangle
The accessory nerve (CN XI) exits the cranial cavity, descends down the neck, innervates sternocleidomastoid and enters the posterior triangle. It crosses the posterior triangle in an oblique, inferoposterior direction, within the investing layer of fascia. It lies relatively superficially in the posterior triangle, leaving it vulnerable to injury.
The cervical plexus forms within the muscles of the floor of the posterior triangle. A major branch of this plexus is the phrenic nerve, which arises from the anterior divisions of spinal nerves C3-C5. It descends down the neck, within the prevertebral fascia, to innervate the diaphragm.
Other branches of the cervical plexus innervate the vertebral muscles, and provide cutaneous innervation to parts of the neck and scalp.
The trunks of the brachial plexus also cross the floor of the posterior triangle.
which muscle splits the posterior triangle into two
omohyoid
what is the posterior triangle split into
The larger, superior part is termed the occipital triangle.
The inferior triangle is known as the subclavian triangle and contains the distal portion of the subclavian artery.
