Mechanisms

Question 1

Name three functions of the lymphatic system

Answer 1

1. Source of WBC
2. Removes excess fluid from the interstitium
3. Removes leaked proteins and pathogens from the interstitium

Question 2

What cranial nerves innervate PA 1-3?

And what muscles do they supply?

Answer 2

1. Trigeminal nerve (mandibular nerve) (muscles of mastication)
2. Facial nerve (chorda tympani) (muscles of facial expression)
3. Glossopharyngeal nerve (stylopharyngeus)

Question 3

What cranial nerves innervate PA 4 and 6?

And what muscles do they innervate?

Answer 3

Both vagus nerve

PA 4: superior laryngeal nerves (cricothyroid muscles)
PA 6: left and right recurrent laryngeal nerves (intrinsic laryngeal muscles)

Question 4

Describe the sympathetic innervation to the head and neck

Answer 4

T1 and T2 preganglionic neurones leave the spinal cords at their respective segments. They both travel to the sympathetic trunk, they then emerge from the sympathetic trunk and coalesce and then enter the SUPERIOR CERVICAL GANGLION or the middle cervical ganglion. The postganglionic fibres synapse as they leave the ganglia. The postganglionic fibres from the SCG either hitch-hike on the ECA or ICA. Fibres on the ECA are destined to innervate the SWEAT GLANDS on the face. Fibres on the ICA are destined to innervate the SUPERIOR TARSAL MUSCLE and DILATOR PUPILLAE.

Question 5

Describe the route the parasympathetic fibres take from the brain to the sphincter pupillae and ciliary bodies.

Answer 5

Preganglioninc parasympathetic fibres emerge from the Edinger-Westphal nucleus in the brainstem and hitch-hike on the oculomotor nerve until the preganglionic parasympathetic fibres synapse in the CILIARY GANGLION. Post ganglionic parasympathetic fibres leave the ciliary ganglion and hitch-hike on the trigeminal nerve until they reach the sphincter pupillae and ciliary bodies of the eye.

Question 6

Describe the route the parasympathetic fibres take from the brain to the parotid gland

Answer 6

Preganglionic parasympathetic fibres from the inferior salivary nucleus leave the and hitch-hike on the tympanic nerve. After the tympanic nerve has formed the tympanic plexus, the nerves leaving this plexus, from the middle ear, is called the lesser petrosal nerve, so the preganglionic fibres continue to hitch-hike on the lesser petrosal nerve until the fibres synapse in the OTIC GANGLION found in the INFRATEMPORAL FOSSA. The postganglionic parasympathetic fibres then hitch-hike on the auriculotemporal nerve (which also exits via the infratemporal fossa) until it reaches the parotid gland.

Question 7

What provides sensory innervation to the supraglottis, glottis and infraglottis?

Answer 7

Supraglottis and Glottis: Internal superior laryngeal nerve

Infraglottis: Recurrent laryngeal nerve

Question 8

During a thyroidectomy, what nerve is most likely to be damaged, and why?

Answer 8

Recurrent laryngeal nerve as the superior thyroid artery is right next to it and this artery is cut out

Question 9

What muscle is responsible for the abduction of the vocal cords?

Answer 9

Posterior criocoarytenoid

Question 10

The movement of which cartilage leads to the movement of the vocal cords?

Answer 10

Arytenoid cartilage

Question 11

How is sound created?

Answer 11

Auricle and EAM funnel SOUND WAVES onto the tympanic membrane leading to its vibration. This leads to ossicles vibrating and stapes vibrates onto the oval window. Perilymph in cochlear duct vibrates, leads to vibration of endolymph in cochlear duct. Stereocilia (a nerve cell, a part of the Spiral organ of corti) on cochlear duct wall move and trigger AP in the cochlear nerve. Cochlear nerve send impulses to Primary Auditory Cortex in the temporal lobe

Question 12

What do all paranasal sinuses drain into and via what?

Answer 12

Drain into the middle meatus via the ostia

Question 13

What is the general sensation of the vestibule of the nose, nasal cavity and the nasopharynx?

Answer 13

Vestibule - V1 (ophthalmic nerve)
Nasal cavity - V2 (maxillary nerve)
Nasopharynx - V2 (maxillary nerve)

Question 14

What nerve carries the general sensation of the 2/3 anterior tongue?

Answer 14

Lingual nerve (Vc branch)

Question 15

Why is the optic disc classed as a blind spot?

Answer 15

It has no photoreceptors

Question 16

What extra ocular muscle drags the eye up and medially?

Answer 16

Inferior obliques

Question 17

What extra ocular muscle drags the eye up and laterally?

Answer 17

Superior rectus

Question 18

What extra ocular muscle drags the eye down and medially?

Answer 18

Superior obliques

Question 19

What structures in the eye aid light refraction onto the macula?

All structures are transparent

Answer 19

Cornea and its associated tear film
Lens
Aqueous and Vitreous chambers

Question 20

How does the eye accommodate to near by objects?

What cranial nerves and what muscles are involved?

Answer 20

Ciliary bodies contract so suspensory ligaments relax so lens fatten (CN III)

Eyes converge into the midline to remain focus on the same point on the retina (CN III medial rectus)

Pupils constrict to limit the amount of light entering (CN III Sphincter pupillae)

Question 21

Describe the production and drainage of aqueous humour, back into the venous system

Answer 21

Produced in ciliary body and then enters posterior chamber. Flows into anterior chamber via pupil. Drained into the canal of Schlemm in the iridocorneal angle

Question 22

What does the aqueous humour lubricate?

Answer 22

Lens and cornea

Question 23

Describe how the posterior pituitary gland is formed

Answer 23

Infundibulum is formed when the neuroectoderm of the forebrain grows downwards towards the pharynx

Question 24

Describe how the anterior pituitary gland is formed

Answer 24

Rathke’s pouch is formed by the ectoderm of the stomatodeum growing upwards towards the forebrain

Question 25

Where does the primordium of the thyroid appear? And what makes up the structures that it appears between?

Answer 25

Appears between tuberculum impar (made from 1st PA) and cupola (made from 2,3,4 PA)

Question 26

If a patient is complaining of ?’ear infection’, why would you ask them - ‘If you pull your ear does it hurt?’

Answer 26

If it DOES hurt - this indicates an abnormality with the external ear canal - most likely have otitis externa

Question 27

With a ?’ear infection’, what neurological exam do you need to do? Why?

Answer 27

Facial nerve exam. Nerve to stapedius and Chorda tympani both pass through the middle ear

Question 28

What salivary gland is most commonly affected by: A) Sialolithiasis B) Sialadenitis

Answer 28

A) Submandibular gland B) Parotid gland

Question 29

Give 2 reasons as to why the submandibular gland is more susceptible to Sialolithiasis.

Answer 29

1. Saliva in the Wharton’s duct flows against the force of gravity (+ the duct is long) 2. Saliva in the submandibular glands are more mucoid (thick) than in the other salivary glands.