Anatomy 6

Question 1

What does the neck contain of?

Answer 1

● pharynx, larynx, and trachea
● the pharynx and oesophagus
● the thyroid and parathyroid glands
● arteries and veins
● nerves that serve the head and neck, upper limbs, thoraco-abdominal viscera (via the vagus nerves) and the diaphragm (via the phenic nerves)
● several groups of muscles, platysma is a very thin subcutaneous muscle deep to the skin of the neck.

Question 2

What is the cervical vertebrae?

Answer 2

7 cervical vertebrae
Small and articulate with each other at facet joints that are orientated obliquely.

This allows for a good range of flexion and extension of the cervical spine, in comparison to the thoracic spine.

Question 3

What is the hyoid bone?

Answer 3

Slender bone situated anteriorly in the upper neck, inferior to the mandible.

It helps to keep the pharynx open and provides an attachment point for several muscles in the neck and of the tongue.

Question 4

What is the Larynx?

Answer 4

Voice Box
Composed of a ‘skeleton’ of small cartilages connected by membranes and small joints.
It protects the airway.
Muscles attach to the laryngeal cartilages and move them, in turn moving the vocal cords and allowing phonation.

Question 5

What are anterior and posterior triangles in the neck separated by?

Answer 5

Sternocleidomastoid muscle

Question 6

What is the sternocleidomastoid muscle?

Answer 6

Sternocleidomastoid (SCM) is attached to the sternum, clavicle, and the mastoid process (part of the temporal bone).

It can act unilaterally or bilaterally (i.e. both the
left and right muscles act together).

It is innervated by the accessory nerve (cranial
nerve XI).

Question 7

What are the boundaries of the anterior triangle?

Answer 7

● the trachea and larynx
● the thyroid gland, parathyroid glands, and the submandibular salivary gland
● the suprahyoid muscles which connect the hyoid to the skull.
● the infrahyoid muscles. Also called the ‘strap’ muscles
● the common carotid artery and its terminal branches (the external and internal carotid arteries)
● branches of the external carotid artery to the head and neck
● the internal jugular vein
● branches of the facial nerve (CN VII), the glossopharyngeal nerve (CN IX),
the vagus nerve (CN X), the accessory nerve (CN XI) and the hypoglossal
nerve (CN XII).
● the ansa cervicalis (fibres from C1-C3 which innervate the infrahyoid muscles).

Question 8

What are the boundaries of the posterior triangle?

Answer 8

● anteriorly: the posterior border of sternocleidomastoid
● posteriorly: the anterior border of trapezius
● inferiorly: the clavicle.

Question 9

What is the apex of the posterior triangle formed by?

Answer 9

Formed by sternocleidomastoid and trapezius.

Question 10

What does the posterior triangle contain of?

Answer 10

● muscles that move the head
● part of the subclavian artery and the subclavian vein
● the external jugular vein which drains the scalp and face
● the accessory nerve (CN XI)
● the roots of the brachial plexus (spinal nerves that supply the upper limb)
● the cervical plexus (fibres from C1-4)
● the phrenic nerve.

Question 11

What are the suprahyoid muscles?

Answer 11

These four paired muscles (mylohyoid, geniohyoid, stylohyoid and digastric) lie superior to the hyoid bone and form the floor of the mouth.

When they contract, they raise the hyoid bone and larynx during speech and swallowing.

Question 12

What are the infrahyoid muscles?

Answer 12

These four paired ‘strap’ muscles lie inferior to the hyoid bone just lateral to the anterior midline of the neck.

They draw the hyoid bone and larynx inferiorly during speech and swallowing.

● Sternohyoid and omohyoid lie superficially; they attach the hyoid to the sternum and scapula, respectively.
● Sternothyroid and thyrohyoid lie deep; they attach the sternum to the thyroid cartilage and the thyroid cartilage to the hyoid, respectively

Question 13

What is the thyroid gland?

Answer 13

The thyroid gland is composed of right and left lobes that lie just lateral to the lower larynx and upper trachea.

Each lobe lies deep to the sternothyroid muscle. The two lobes are joined by the isthmus, which lies anterior to the trachea.

The thyroid gland produces hormones which play an important role in the regulation of metabolic processes.

The pituitary gland regulates hormone secretion from the thyroid gland.

Question 14

What is the thyroid gland supplied by?

Answer 14

The thyroid gland has a rich blood supply via the:

● left and right superior thyroid arteries - branches of the external carotid arteries
● left and right inferior thyroid arteries - branches of the thyrocervical trunks (which in turn are branches of the subclavian artery)

Some people have an additional thyroid ima artery. Superior, middle, and inferior thyroid veins drain the thyroid gland.

Question 15

What are the Parathyroid glands?

Answer 15

There are usually four parathyroid glands
- right and left superior and inferior glands
- located posterior to the thyroid gland.

They produce parathyroid hormone which
plays a role in calcium regulation.
They are typically supplied by the inferior thyroid
arteries.

Question 16

What do the common carotid arteries ascend and bifurcate into?

Answer 16

Ascend in the right and left sides of the neck,
respectively.
The pulsation of the internal carotid can be palpated immediately lateral to the larynx.
The common carotid arteries bifurcate into external and internal carotid arteries.

Question 17

What is the internal carotid artery?

Answer 17

Does not give rise to any branches in the neck.
It enters the cranium and supplies the brain.

Question 18

What is the external carotid artery?

Answer 18

The external carotid artery gives rise to several branches that supply the head and neck,
including the pharynx, scalp, thyroid gland, tongue, and the face.

Question 19

What is the carotid sinus?

Answer 19

Point of bifurcation of the common carotid artery there is a small swelling

Baroreceptors here constantly monitor arterial
blood pressure.
This visceral sensory information is relayed back to the CNS via the glossopharyng

Question 20

What does the subclavian artery supply?

Answer 20

Upper Limbs

Question 21

What does the thyrocervical trunk give rise to?

Answer 21

Inferior thyroid artery

Question 22

What is the internal jugular vein?

Answer 22

The internal jugular vein is a major vein in the neck, which drains blood from the brain and part of the face.

● It unites with the subclavian vein, which returns blood from the upper limb, to form the brachiocephalic vein.
● The right and left brachiocephalic veins unite to form the superior vena cava.

Question 23

What does the external jugular vein do?

Answer 23

The external jugular vein drains blood from the scalp and face.
It joins the subclavian vein.

Question 24

What does the facial nerve (CN VII) supply?

Answer 24

Supplies platysma in the neck.

Question 25

What does the glossopharyngeal nerve (CN IX) supply?

Answer 25

● pharynx (sensory innervation) ● carotid sinus (visceral sensory fibres that return to the CNS via CN IX)

Question 26

What does the vagus nerve supply?

Answer 26

Vital for normal speech and swallowing ● the muscles of the pharynx (motor innervation) ● the larynx (motor and sensory innervation)

Question 27

Where does the vagus nerve run?

Answer 27

Runs between the internal jugular vein and the internal carotid artery (above its bifurcation) and between the internal jugular vein and common carotid artery (below its bifurcation). The three structures run together in a fascial sleeve called the carotid sheath.

Question 28

What does the accessory nerve (CN XI) supply?

Answer 28

Supplies the sternocleidomastoid and trapezius muscles.

Question 29

What is the hypoglossal nerve (CN XII)?

Answer 29

Is motor to the muscles of the tongue. It does not supply any structures in the neck but travels through it. It lies lateral to the internal carotid artery and deep to the external jugular vein.

Question 30

What is the phrenic nerve formed by?

Answer 30

Formed by C3, C4 and C5 nerve fibres. It descends through the neck to enter the thorax. It innervates the diaphragm.

Question 31

What is the head and neck innervated by?

Answer 31

Innervated by sympathetic nerves

Question 32

What is throidectomy?

Answer 32

Removal of the thyroid gland (e.g. for thyroid cancer) risks injury to the recurrent laryngeal nerves, which lie close to the inferior thyroid arteries. The nerve may be cut when the artery is ligated. Injury to the recurrent laryngeal nerve results in an inability to move the ipsilateral vocal cord and this affects the quality of the voice. Another risk of thyroidectomy is that the parathyroid glands may be removed, which disturbs calcium homeostasis. After thyroidectomy, patients must take hormone replacements.

Question 33

What is the clinical relevance of penetrating injuries to the neck?

Answer 33

Because the neck contains vital neurovascular structures located very closely to each other, penetrating injuries such as stab wounds often injure multiple structures. Such injuries are often fatal or cause severely debilitating injuries.

Question 34

What is the Carotid artery stenosis?

Answer 34

Atheroma (fatty plaque) in a carotid artery narrows the lumen (stenosis) and impedes blood flow to the brain. If a plaque breaks up, fragments of the plaque and thrombus will be carried up into the cerebral arteries, causing a stroke which could be fatal or severely debilitating. To prevent this, atheroma can be surgically removed from the wall of the carotid artery in a procedure called a carotid endarterectomy. The procedure carries a risk of severe bleeding from the carotid artery and stroke.

Question 35

What is a central line insertion into the jugular vein?

Answer 35

In patients who are very unwell and need fluid and drugs intravenously, a large line with multiple ports can be placed into a large central vein. The IJV is the vein of choice, as it is relatively easy to access and can be easily visualised with ultrasound.