Where does the neck extend anteriorly?
From lower border of mandible down to manubrium
Where does the neck extend posteriorly?
From the superior nuchal line down to C7/T1 disc
What does the superior nuchal line give attachment to?
Trapezius
What is the neck divided into?
A series of longitudinal compartments/cylinders.
What is each compartment of the neck contained within?
Layers of cervical fascia
What are the 3 compartments of the neck?
Vertebral, vascular and visceral.
What is the vertebral compartment?
Posterior compartment containing cervical vertebrae and postural muscles.
What is the vascular compartment?
Lateral compartment comprising carotid sheath and its contents: common carotid artery, internal jugular vein, vagus and deep cervical lymph nodes.
What is the visceral compartment?
Anterior compartment containing thyroid gland, parathyroid gland and the thymus gland (if present), the trachea and oesophagus.
What encloses all of the compartments of the neck?
Superficial and deep fascial layers.
What is the platysma?
The thin sheet of muscle contained within the superficial fascia.
What does platysma blend with?
The muscles of the face
Where does platysma get its nerve supply?
- Shares nerve supply because it’s technically a muscle of facial expression
- Innervated by the cervical branch of the facial nerve (CNVII)
Which important superficial veins are within the superficial fascia?
External and anterior jugular veins
What do the external and anterior jugular veins drain?
Superficial structures of the neck.
What are the 4 different deep fascial layers of the neck?
Investing fascia, pretracheal fascia, prevertebral fascia and carotid sheath.
What does the investing fascia surround?
All of the cylinders/compartments (visceral, vertebral and visceral).
What does the investing fascia split to enclose?
Trapezius posteriorly and sternocleidomastoid anteriorly.
What does the prevertebral fascia surround?
- Surrounds the vertebral compartment
- In front of and behind the prevertebral structures
- Cervical vertebrae
- Associated muscles
- Cervical vertebrae
- Associated muscles
What 2 fascial layers create the pretracheal fascia?
Pretracheal fascia and buccopharyngeal fascia
Which compartment does the pretracheal fascia enclose?
Visceral compartment
Which bone does the pretracheal fascia attach to?
Hyoid bone
Why will the visceral compartment move with swallowing?
Because the pretracheal fascia is attached to the hyoid bone.
What is the carotid sheath?
Column of fascia surrounding the common carotid artery, internal jugular vein and vagus nerve.
What lies between all of the fascial spaces. What does this mean pathologically?
There are spaces between all of these fascial spaces, they communicate below with the mediastinum, therefore any infection in the neck, e.g. abscess, that collects in one of these spaces will track straight down into the mediastinum and create mediastinitis.
What are the 2 different regions of the neck?
Anterior and posterior triangle.
What is the anterior triangle bounded by?
Sternocleidomastoid, inferior border of mandible and midline of the neck (therefore 2 triangles anteriorly)
What are the 2 muscles of the anterior triangle?
Suprahyoid and infrahyoid muscles
What are the suprahyoid muscles?
Muscles connecting the hyoid bone to the skull.
What creates the floor of the mouth?
The suprahyoid muscles.
What does the suprahyoid muscles do?
Elevate the hyoid and larynx.
What are the infrahyoid muscles?
Long vertical strap muscles
What do the infrahyoid muscles do?
- Anchor hyoid above down to the sternum or the clavicle or scapula below
- Depress hyoid or larynx
Where do the muscles of the anterior triangle lie?
Between investing fascia and pretracheal fascia
What do the muscles of the anterior triangle do?
Act to steady or move the hyoid bone and larynx
What innervates the muscles of the anterior triangle?
Anterior rami of cervical nerves
What sits within the anterior triangle of the neck?
Muscles, carotid system, veins, nerves and thyroid gland.
Where is the carotid system found?
In the anterior triangle.
Which arteries comprise the carotid system in the anterior triangle?
Common carotid, internal carotid and external carotid.
What are the 6 branches off the external carotid?
- 3 off front
- Superior thyroid artery (supplies thyroid gland)
- Lingual artery (supplies oral cavity)
- Facial artery (winds across inferior border of mandible to medial angle of eye)
- 2 off back
- Occipital artery
- Posterior auricular artery
- 1 deep
- Ascending pharyngeal artery (supplies deeper structures associated with pharynx and larynx)
- Superior thyroid artery (supplies thyroid gland)
- Lingual artery (supplies oral cavity)
- Facial artery (winds across inferior border of mandible to medial angle of eye)
- Occipital artery
- Posterior auricular artery
- Ascending pharyngeal artery (supplies deeper structures associated with pharynx and larynx)
What are the 3 arteries off the front of the external carotid?
- Superior thyroid artery (supplies thyroid gland)
- Lingual artery (supplies oral cavity)
- Facial artery (winds across inferior border of mandible to medial angle of eye)
What are the 2 arteries off the back of the external carotid?
- Occipital artery
- Posterior auricular artery
What is the 1 deep artery of the external carotid?
Ascending pharyngeal artery (supplies deeper structures associated with pharynx and larynx)
Which vein is found in the anterior triangle?
Internal jugular vein lateral to the common carotid artery in the carotid sheath
Which cranial nerves are present in the anterior triangle? How do they enter the anterior triangle?
- Jugular foramen: CNIX, CNX, CNXI
- Hypoglossal canal: CNXII
Where does the glossopharyngeal nerve (CNIX) travel in the anterior triangle?
Passes forward to oropharynx, providing pharyngeal, tonsillar and tympanic innervation as well as lingual innervation to the posterior 1/3 of the tongue.
Where does vagus nerve (CNX) travel in the anterior triangle?
Travels down, descending in the carotid sheath providing somatic sensory to the mucous membrane of larynx and branchial motor to muscles of pharynx, larynx & soft palate
Where does the accessory nerve (CNXI) travel in the anterior triangle?
Passes backwards, goes through or beneath sternocleidomastoid
Where does the hypoglossal nerve (CNXII) travel in the anterior triangle?
Passes forwards in front internal and external carotids and behind internal jugular vein providing motor supply to the tongue (except palatoglossus).
What side will the tongue deviate to if there's a lesion of the hypoglossal nerve?
The affected side.
Where is the thyroid gland located?
2 lobes between upper border of thyroid cartilage above & 6th tracheal ring below with an isthmus, between 2nd & 3rd tracheal rings connecting the lobes.
What encloses the thyroid gland?
Pretracheal fascia
What thyroid structure is present in 50% of the population?
A pyramidal lobe extending up from the isthmus, classically veering to the left.
What does the thyroid lie deep to?
Strap muscles
What does the thyroid lie lateral to?
Trachea and oesophagus (wrapping around them)
What does the thyroid lie adjacent to and overlap?
Carotid sheaths
What happens to the recurrent laryngeal nerves at the level of the thyroid?
They are embedded into the fascia on the back of the thyroid gland. Intimately related.
What can enlargement of the thyroid compress?
- Trachea (presenting as respiratory obstruction)
- Oesophagus (presenting as dysphagia)
- Recurrent laryngeal nerves (presenting as hoarse voice)
- Internal jugular veins (presenting as venous distension of unknown cause).
What provides blood supply to the thyroid gland?
- Paired superior thyroid (usually 1st branch of external carotid a.)
- Paired inferior thyroid (branch of subclavian a.)
Which artery occasionally (10%) provides blood to the thyroid gland?
Single thyroid ima a. passes along isthmus
Which 3 veins drain the thyroid gland?
Superior, middle, inferior thyroid
How does the thyroid develop?
As an outgrowth from the floor of the embryonic pharynx and descends ventral to the larynx before dividing into 2 lobes.
What is the foramen caecum?
The site of origin of the thyroid gland and the thyroglossal duct marks the path of descent to the adult location. This usually disappears.
What can often be seen along the path of descent of the thyroid gland?
Nodules of aberrant thyroid tissue can often be seen anywhere along this path of descent.
What could someone with signs of hyperthyroidism but a seemingly normal thyroid gland have?
Could have a hot secretory nodule
Where is the posterior triangle of the neck?
Behind sternocleidomastoid, in front of trapezius and above middle 1/3 of clavicle.
What structures are present in the posterior triangle of the neck?
Deep muscles of the neck, accessory nerve, peripheral nerves and subclavian system.
What are the deep muscles of the neck and back?
Pre- & post-vertebral muscles - pass almost vertically across 5-7 spinal segments
What forms the floor of the posterior triangle?
A series of obliquely oriented deep vertebral muscles - levator scapuli and scalenus medius.
What covers the muscles in the posterior triangle of the neck?
Prevertebral fascia
What emerges from between scalenus medius and scalenus anterior?
Brachial plexus component parts
Where do the beginnings of the brachial plexus occur?
In floor of posterior triangle (roots and trunks), deep to prevertebral fascia
What part of the posterior triangle do nerves of the upper limb traverse?
Lower part and then pass between the clavicle and the first rib into the upper limb.
Where in the posterior triangle do the key neurovascular structures of the upper limb emerge from? What are these structures?
Subclavian vessels and roots and trunks from the C5, C6, C7 and T1 nerve traverse the lower part of the posterior triangle, passing beneath the clavicle, between it and the first rib and on into the upper limb.
What does the subclavian artery supply?
Upper limb, almost ½ brain, most of spinal cord (via vertebral artery) & part of thoracic wall
What are the main branches of the subclavian artery in the neck?
- Vertebral (normally 1st branch) – passes in triangle between longus colli & scalenus anterior
- Thyrocervical trunk (gives off inferior thyroid to thyroid gland)
Where does the accessory nerve (CNXI) pass in the neck?
Into top of anterior triangle from the jugular foramen, goes beneath or through sternocleidomastoid, drops onto floor of posterior triangle, crosses it obliquely and directly relates to levator scapulae and then disappears under the cover of trapezius.
What does the accessory nerve (CNXI) supply in the neck?
Sternocleidomastoid and trapezius.
How can a surgeon who has operated in the area of the posterior triangle test to see if he has damaged the accessory nerve?
By getting the patient to shrug their shoulders afterwards.
Which plexus is present in the posterior triangle?
Cervical plexus
Where does the cervical plexus form?
Under the cover of sternocleidomastoid
What is the most important branch of the cervical plexus?
Phrenic (C3,4,5) branches
Where does the cervical plexus descend?
On scalenus anterior in the posterior triangle
What are the 3 branches of the cervical plexus?
Phrenic, superficial and deep.
What does the superficial branch of the cervical plexus supply?
Cutaneous branches to skin
What does the deep branch of the cervical plexus supply?
Ansa cervicalis (motor to ‘strap’ muscles of neck – attach to hyoid)
What do the roots (rami) of brachial plexus pass between?
Scalenus medius & anterior
What are the 2 rings of cervical lymph drainage?
Superficial and deep cervical lymph nodes.
What are the 2 groups of superficial cervical lymph nodes?
- Horizontal (junction of head/neck)
- Vertical (along external jugular)
What are the 2 groups of deep cervical lymph nodes?
- Upper group (includes jugulo-digastric or tonsillar node – drains palatine tonsil)
- Lower group (includes supraclavicular – ‘final sentinel’ node - clinical significance)
