POSTERIOR TRIANGLE

Question 1

Why is the posterior triangle clinically important

Answer 1

For IVP, and central vein catheterisation

Question 2

What does the superficial fascia of the neck encompass

Answer 2

Fatty tissue and the platysma muscle

Question 3

Describe the platysma

Answer 3

Thin sheet of skeletal muscle attached to lower facial muscles. Innervated by cervical branches of the facial nerve

Question 4

What are the four layers that make up the deep fascia

Answer 4

The investing layer, the pre tracheal layer, the carotid sheath and the prevertebral layer

Question 5

Describe the investing fascia

Answer 5

Also called the superficial layer of the deep fascia. Surrounds the peripheral neck muscles trapezius, sternocleidomastiod, straps.

Question 6

Describe the pre tracheal layers

Answer 6

Encloses the thyroid, larynx/ trachea, pharynx/oesophagus

Question 7

What does the carotid sheath surround

Answer 7

The carotid artery, the internal jugular vein and the vagus nerve. It is connected to and reinforced by adjacent layers of fascia at different levels.

Question 8

What does the prevertebral layer surround

Answer 8

The vertebral column and paravertebral muscles

Question 9

What are the three potential spaces in the neck and what are their clinical relevance

Answer 9

Pre tracheal space
Retropharyngeal space
Pre vertebral space
Where disease may locally spread from the neck to the mediastinum. You don’t see the spaces in dissection but do on imaging

Question 10

Label the regions of the neck

Answer 10

Under mandible 1, inferior to this (medial neck) 6, lateral neck superior to inferior 2, 3, 4, posterior triangle 5

Question 11

What are the borders of the posterior triangle

Answer 11

Anterior: posterior border of sternocleidomastiod
Posterior: anterior border of trapezius
Roof: Investing layer of deep fascia, superficial fascia, platysma muscle, skin
Floor: prevertebral fascia, paravertebral muscles

Question 12

What neurovascular structures are found in the superficial fascia of the neck

Answer 12

Cutaneous nerves and superficial veins, including posterior external jugular vein

Question 13

What arteries are found in the posterior triangle and where

Answer 13

The third part of the subclavian artery crosses the base (goes on to form auxiliary artery)
Transverse cervical and suprascapular arteries cross base both branches of the thyrocervical trunk (off first part of subclavian).
At the apex the occipital artery is found

Question 14

What nerves are found in the posterior triangle and location

Answer 14

The accessory nerve. Running in investing fascia enters about half way down posterior border of sternocleidomastoid and travels obliquely and inferiorly to trapezius.
~2 cm below where CXI enters triangle is Erbs point where 4 superficial branches of the cervical plexus enter the triangle lesser occipital, great auricular, transverse cervical, supraclavicular. Supraclavicular one most in triangle others tract more medially.
Trunks of the brachial plexus cross the base of the posterior triangle

Question 15

Describe the path of the accessory nerve

Answer 15

Exits jugular foramen, passes posteriorly to reach the anterior border of sternocleidomastoid and either passes through or under innervating it. Reaches posterior border where it enters the posterior triangle crossing it within the superficial layer of deep cervical fascia (investing fascia) obliquely and inferiorly to the trapezius muscle where it passes deep innervating it.

Question 16

What veins are found in the posterior triangle

Answer 16

The posterior external jugular vein passes obliquely across the triangle to join the external jugular which pierces the investing fascia in anterior corner of the triangle to join the subclavian vein.

Question 17

Which nerve is at risk of iatrogenic injury following lymph node biopsies in the posterior triangle

Answer 17

The accessory nerve due to its long and relatively superficial course.

Question 18

Where do lymphatics run in the neck

Answer 18

Superficial cervical nodes run along external jugular vein

Deep cervical node run along the internal jugular vein

Question 19

If deep cervical nodes are enlarged can you predict location of pathology

Answer 19

No as all nodes from the head drain to them, to unspecific.

Question 20

What needs to be considered with posterior triangle dissection

Answer 20

The anatomical variance in the course of the spinal accessory nerve. To avoid damage USS should be used

Question 21

What is the most common reason for neck dissection

Answer 21

Removal of lymph nodes and firbofatty tissue in cancer therapeutic or elective (preventative or treatment respectively)

Question 22

What form of head and neck cancer is almost always indicative for lymph node dissection

Answer 22

Oral tongue

Question 23

Features suggestive of metastasis in lymph nodes

Answer 23

Node larger than 1cm
Round not oval
Central necrosis