6 : Larynx & Pharynx 🗣️

Question 1

What would be a likely explanation of a patient’s complaining of a hoarse voice following a total thyroidectomy?

Answer 1

Trauma to one of the recurrent laryngeal nerves (a branch on the vagus nerve) which supply efferent (motor) innervation to the vocal cords ipsilaterally.

Question 2

If surgery was not to be a likely cause, what other disorders in the neck would you consider that may lead to a hoarse voice?

Answer 2

•Lung tumour

•Thyroid nodule

•Hyperplasia of thyroid tissue

Question 3

In any patient what other left-sided cardiovascular/defect in the thorax would probably cause left vocal cord palsy?

Answer 3

•Aortic aneurysm may leasd to compression of the left recurrent laryngeal nerve.

•This is a nerve compression syndrome that might lead to the death of the left recurrent laryngeal nerve, hence left vocal cord palsy

Question 4

What cranial nerve is stimulated on tickling the soft palate to elicit a “gag reflex”?

Answer 4

Also known as the pharyngeal reflex

Afferent Limb of Reflex

•Supplied by the glossopharyngeal nerve (cranial nerve IX), which inputs to the nucleus solitarius and the spinal trigeminal nucleus

Efferent Limb of Reflex

•Supplied by the vagus nerve (cranial nerve X) from the nucleus ambiguus. Absence of the gag reflex can be a symptom of a number of severe medical conditions, such as damage to the glossopharyngeal nerve, the vagus nerve, or brain death

Question 5

In a patient who has tonsilitis, which single palpable lymph node would you expect to be enlarged?

Answer 5

Jugulo-digatsric Node (Tonsillar): This node is located just below the angle of the mandible. It is labelled 9 in the diagram opposite

Question 6

A pharyngeal pouch may occur, particularly in the elderly. What is its anatomical explanations?

Answer 6

A pharyngeal pouch is a pulsion diverticulum of the pharyngeal mucosa through a weakening between the cricopharyngeus and thyropharyngeus muscles at the top of the oesophagu. These muscles collectively form the upper oesophageal sphincter. The pressure generated by swallowing can over time result in an out-pouching of the underlying mucosa through this weakness in the muscles. The exact reason why some people get pharyngeal pouches and others do not is unknown, but several theories exist. The more well known include incoordination of the swallowing reflex, resulting in more pressure in the superior oesophageal sphincter, which results in a pulsion diverticulum forming

Question 7

On a lateral soft tissue radiograph of the neck, some laryngeal skeleton appears dense as bone and non-transluscent. Comment on the likely explanation of this occurrence in such a patient

Answer 7

This is due to ossification (&/or calcification) of the laryngeal skeleton and can occur spontaneously in some adults, with females showing less or a frequency to this than men

Question 8

A 25-year old woman visited her GP because of a painless swelling just beneath her hyoid bone. No other neck mass or lymphadenopathy was present. Laboratory tests showed absence of radioactive iodine in the swelling. What is the probable cause of the swelling?

Answer 8

The swelling is a cyst that may have arisen from the remnant of the thyroglossal duct, an embryonic structure formed during migration of the thyroid from the base of the tongue (at the foramen cecum) to its final position in the neck. The foramen cecum is a normal remnant of the thyrogloosal duct.

Question 9

Why would you be concerned about lymphadenopathy in the neck?

Answer 9

Cancerous growth or infections of the structures anywhere in the neck may lead to the enlargement

of the lymph nodes

(deep cervical nodes) which drain almost all the lymph from the head and neck region.

Question 10

What do you infer from the laboratory finding of the absence of radioactive iodine in the swelling?

Answer 10

Absence of radioactive iodine in the swelling indicates the absence of thyroid tissue in the cyst; presence of radioactive iodine may otherwise indicate functioning thyroid tissue.

Question 11

What is The Levator Glandulae Thyroideae?

Answer 11

The levator glandulae thyroideae is a fibrous band which connects the isthmus of the thyroid gland to the hyoid bone. It may contain muscle.

Question 12

What is the role of infrahyoid muscles during swallowing?

Answer 12

During the swallowing, the larynx is lifted by the suprahyoid muscles preventing the influx of food into the airway. The infrahyoid muscles stabilise the larynx by opposing the actions of suprahyoids during swallowing.

Question 13

Why does the thyroid gland move during swallowing?

Answer 13

Part of the pretracheal fascia forms the sheath of the thyroid gland. Superiorly, it is attached to the thyroid and cricoid cartilages. Having enclosed the gland, the pretracheal fascia passes inferiorly to enclose the inferior thyroid veins and then blend with the posterior surface of the pericardium at the bifurcation of the trachea. Thus, when the laryngeal skeleton ascends during swallowing, the thyroid gland moves up as well

Question 14

Explain (in functional terms) why the inferior thyroid artery is tortuous in structure

Answer 14

The tortuous structure of the inferior thyroid artery is due to the fact that on every swallow the thyroid gland ascends a few centimetres and must naturally drag its arterial supply with it. If this artery had no capability to elongate, it would be traumatised.

Question 15

Why is C6 vertebral level an important landmark in the neck?

Answer 15

C6 is at a number of important landmarks:

- the junction of the larynx with the trachea

- the junction of the pharynx with the oesophagus

- the site at which the carotid artery can be compressed against the transverse process of C6 (the carotid tubercle)

- the level at which the vertebral artery (a branch of the subclavian artery) enters the transverse foramen in the 6th cervical vertebra

- the level at which the superior belly of the omohyoid crosses the carotid sheath

- the level at which the inferior thyroid artery enters the thyroid gland and the middle thyroid vein emerges out of the gland

- the level of the middle cervical sympathetic ganglion

Question 16

Why may a parathyroid gland be found within the thymus gland retrosternal position?

Answer 16

The two pairs of the parathyroid glands develop from the 3rd and 4th pharyngeal pouches. The glands from the 3rd pouch usually migrate caudally with the thymus gland, going past the glands form the 4th pouch which lie in the fascial sheath in the upper part of the thyroid gland. Variations in number, size and position are common and aberrant 3rd pouch parathyroid glands may descend with the thymus to a retrosternal position instead of the more common site in the inferior lobe of the thyroid gland.

Question 17

What is the function of the ‘carotid sinus’?

Answer 17

At the bifurcation of the common carotid artery into the external and internal carotid arteries, there is a slight dilation of the proximal part of the internal carotid artery called the carotid sinus. It is supplied mainly by the glossopharyngeal (IX) nerve through the carotid sinus nerve; the vagus nerve (X) also innervates it. The carotid sinus is a baroreceptor that is stimulated by changes in arterial blood pressure.

Question 18

Where would expect to find the ‘carotid body’ and what is its function?

Answer 18

The carotid body lies deep on the medial side of the bifurcation of the common carotid artery in close relation to the carotid sinus. It is innervated by IX and X cranial nerves. It is a chemoreceptor that monitors the level of oxygen and carbon dioxide in the blood. Low levels of oxygen initiates a reflex that increases the rate and depth of respiration, cardiac rate and blood pressure.

Question 19

How would you easily distinguish the internal from the external carotid artery in the neck on a carotid arteriogram?

Answer 19

The internal carotid artery has no branches in the neck, its first branch being the ophthalmic artery. The external carotid artery has numerous large branches to the thyroid gland (superior thyroid artery), tongue(lingual artery), ear, occiput(superficial temporal artery) and face(facial artery).

Question 20

In addition to the vagus nerve, what other important nerves might be damaged in a carotid arteriogram puncture?

Answer 20

The vagus nerve, with its many branches to the larynx and pharynx, is an immediate posterior relation of the carotid artery. The sympathetic chain lies just outside the carotid sheath on the prevertebral fascia. All these nerves are vulnerable to injury if the needle penetrates too deeply.