Posterior triangle of the neck Flashcards
What are the layers of the neck and what do they surround?
Superficial fascia - skin and fatty layer
Deep fascia: 3x + the carotid sheeth.
Investing fascia - invests the sternocleidomastoid muscles, the infrahyoid muscles (strap) and the trapezius muscle
Pretracheal - trachea, thyroid, pharynx/oesophagus (below C6)
Prevertebral - vertebrae, muscles that originate from the spine (anterior, middle and posterior scalene muscles, muscles either side of the vertebrata)
These three facia make up the carotid sheeth.
Carotid sheath - composed of the fascia from the other fascias (not a separate entity). Internal jugular, common carotid and vagus.
Where is the platysma muscle?
Under the superficial fascia of the neck and above the investing layer. Attaches to the mandible superiority and the clavicle inferiority.
Innervated by CNVII
What is important about the prevertebral layers of the fascia?
There are two layers over the anterior part of the vertebral body. It sits behind the buccopharyngeal fascia (posterior part of the pretracheal fascia).
This is called the danger zone
Where are the four potential spaces in the neck?
Pretracheal space - Between the investing fascia and the pretrachial fascia. Thyroid infections can drain here.
Retropharyngeal space - behind the buccopharyngeal fascia and in front of the preverterbral fascia.
Prevertebral space - Fascial space within the prevertebral layers
Posterior triangle of the neck
What are the structures on the boundary of the posterior triangle? Identify it on a cross-section
Posterior border of the the sternocleidomastoid muscle
Anterior border of the trapezius
Superior border of the clavical
Roof is superficial to the investing layer
Floor is the prevertebral fascia and the muscles that sit deep to it: levator scapulae, splenius capitus and anterior, middle and posterior scalene.
What are the contents of the posterior triangle?
Neurovascular structures, lymph nodes, muscular structures.
Accessory nerve runs in the posterior triangle CNXI - lots of accessory nerve injury due to surgical injury. Just deep to the investing layer is the accessory nerve on the border of the sterneocleidomastoid and running to the trapezius. You need to use ultrasound to identify.
When these nerves get to erb’s point (posterior border of sternocleidomastoid then they branch and go to the destination. Only the beginning is in the posterior triangle then it perforates the investing layer and runs in the superificial fascia. Sensory nerves.
Great auricular nerve -either side of the ear
Lesser occipital nerve - occipital area
Transverse cervical nerve - anterior part of the neck
Supraclavicular nerve - above the clavicle
A part of the brachial plexus is there - good place to use a nerve block.
The great auricular nerve is the first nerve that will be seen and runs 2 cm below the accessory nerve but in different plains (deeper plains).
The third part of the Subclavian arteries
Transverse cervical artery and suprascapular arteries - base of the triangle - branch of the - subclavian artery -> thyrocervical -> 2 branches (suprascapular and the transverse cervical).
The inferior belly of the omohyoid.
What is in the roof of the posterior triangle?
Platysma, superficial fascia
Internal and external jugular vein are within the roof but perforate the investing fascia and enter the posterior triangle.
Terminal parts of nerves are in the roof.
Where does the accessory nerve run in the posterior triangle and how can you find it?
No surface marking. The great auricular nerve is the first nerve that will be seen and runs 2 cm below the accessory nerve but in different plains.
Easily damaged during cervical lymph biopsy. They are very close.
You need to use ultrasound to identify.
What does damage to the accessory nerve do?
Can’t use trapezius. Can’t abduct the arm (difficulty reaching shelf, putting on jacket
Where can you do a central vein catheterization?
Anterior triangle. Between the two distal heads of the sternocleidomastoid into the internal jugular vein.
What is the lymphatic drainage of the neck?
Lymphatics: Superficial and deep cervical lymphatics in the neck. Superficial around the bottom of the skull. Occipital nodes, mastoid nodes, parotid nodes, submandibular nodes and submental nodes.
The occipital and mastoid drain to the superficial cervical lymph nodes.
The parotid, submandibular and submental drain into deep cervical lymph nodes.
Eventually all drain to the deep nodes.
What is at risk during a cervical lymph node biopsy?
• Accessory nerve (just under the skin)
o Ask patient to shrug shoulder to check/fully abduct the arm
• May damage superficial branch of transverse cervical artery
o Patient has an enlarged neck, needs drainage
• Cutaneous and great auricular nerve also at risk
What is at risk when placing a central catheter?
• External jugular vein (some bleeding)
• Accessory nerve (due to variations)
• May have bleeding within carotid sheath
o Pressure placed on vagus (X) nerve, internal carotid/common carotid
o Some vagus symptoms such as pain, muscle cramps, difficulty in swallowing
