Posterior triangle Flashcards
what is the posterior triangle of the neck also known as?
lateral cervical region
anterior border of posterior triangle?
posterior border of SCM
posterior border of PT?
anterior border of trapezius
inferior border of PT?
middle 1/3 of clavicle
what is the posterior triangle covered by?
investing layer of fascia (most superficial)
what is the floor of the PT formed by?
prevertebral fascia (deepest)
what is a significant muscle in the posterior triangle region?
omohyoid muscle
what is the omohyoid muscle split into? by what?
split into 2 bellies by a tendon
where does the inferior belly of the omohyoid muscle travel after it crosses the PT?
in an supero-medial direction, splitting the posterior triangle into 2
muscle then crosses under SCM to enter anterior triangle
which muscles form the floor of the posterior triangle?
splenius capitis
levator scapulae
anterior, middle and posterior scalene
what are the muscles forming the floor of the PT covered by?
prevertebral fascia (deepest)
which is the major vein of the neck region?
external jugular vein
what is the external jugular vein formed by?
retromandibular and posterior auricular veins
where does the EJV lie?
superficially
where does the EJV enter the PT?
after crossing the SCM
what happens within the PT in terms of the EJV?
EJV pierces the investing layer of fascia (superficial deep)
where does EJV empty into after piercing investing layer of fascia?
subclavian vein
what is the subclavian vein normally used as?
a point of access to venous system via central catheter
which veins aside from EJV also lie in PT?
transverse cervical
suprascapular veins
what are subclavian, transverse cervical and suprascapular veins accompanied by in the PT?
their respective arteries
which part of the subclavian artery can be located? how?
distal part of subclavian artery
it emerges between the anterior and middle scalene muscles
where does the subclavian artery end?
crosses the 1st rib
becomes axillary artery - supplies upper limb
clinical: why is the EJV vulnerable to damage?
has relatively superficial course down the neck
clinical: what happens if the EJV is severed? in what injury?
injury e.g. knife slash
lumen held open
clinical: why is lumen of EJV held open in severance?
due to thick layer of investing fascia, air will be drawn into vein
clinical: what does lumen of EJV being held open in severance produce?
cyanosis
can stop blood flow through the right atrium
clinical: how do you manage severance of the EJV?
medical emergency
application of pressure to the wound, stopping bleeding and entry of air
which nerve runs through the PT?
accessory nerve (CN XI)
how does the accessory nerve (CN XI) enter the PT?
exits the cranial cavity, descends down the neck, innervates SCM and enters the posterior triangle in an oblique, inferoposterior direction
where does the accessory nerve (CN XI) travel as it enters the PT?
within the investing layer of fascia
relatively superficial in PT - vulnerable to injury
what forms within the muscles of the floor of the PT?
cervical plexus
what is a major branch of the cervical plexus?
phrenic nerve
where does phrenic nerve arise?
anterior division of spinal nerves (C3-C5)
where does phrenic nerve travel?
descends down the neck, within the prevertebral fascia (deepest)
what does the phrenic nerve innervate?
diaphragm
what do other branches of the cervical plexus innervate?
the vertebral muscles
provide cutaneous innervation to parts of the neck and scalp
what else crosses the floor of the posterior triangle?
trunks of the brachial plexus
clinical: for anaesthesia of the neck area, which nerve block is used?
cervical plexus block
clinical: where is the anaesthetic injected in a cervical plexus block?
injected along the posterior border of SCM at junction of its superior and middle 1/3s
what is significant about the superior and middle 1/3 of the SCM?
junction where the cutaneous branches of the cervical plexus emerge - nerve point of the neck
in which patients is a cervical nerve block not carried out? why?
patients with pulmonary or cardiac problems
runs a high risk of damaging phrenic nerve
which structure subdivides the PT?
omohyoid muscle
splits PT into 2 regions
what are the 2 regions of the PT divided by omohyoid muscle?
occipital and subclavian triangle
which part is the occipital triangle?
larger, superior part
which is the subclavian triangle?
inferior triangle of PT
what does the subclavian triangle contain?
distal portion of subclavian artery
