Question 1

Which cranial nerves emerge from the cerebellopontine angle?

Accepted Answer

Facial (VII)7 Vestibulocochlear (VIII)8 ?Trigeminal (V)5 (comes off pons)

Question 2

Which cranial nerves emerge from the interpeduncular fossa?

Accepted Answer

Optic (II)2 Oculomotor (III)3

Question 3

Which cranial nerves emerge immediately lateral to the medullary pyramid?

Accepted Answer

Hypoglossal (XII)12

Question 4

Where are the true, peripheral olfactory nerves? How do they enter the cranial cavity?

Accepted Answer

The sensory cells of the nasal mucosa project their axons into the CNS. These tiny fibres that are the true peripheral olfactory nerves, pierce the cribriform plate of the ethamoid bone and synapse in the olfactory bulb, which is part of the CNS.

Question 5

Suggest the mechanism by which the olfactory nerve might be damaged during head injury.

Accepted Answer

Disruption of the olfactory fibres prior to their decussation.

Question 6

How might a patient's visual fields be tested?

Accepted Answer

The visual fields of both eyes overlap; therefore each eye is tested independently. The patient should cover their right eye with their right hand (vice versa when testing the opposite eye). With the examiner seated directly across from the patient, the patient should direct their gaze to the corresponding eye of the examiner. A moving target should start outside the usual 180 º visual field, then move slowly to a more central position until the patient confirms visualization of the target. All 4 quadrants (upper and lower, temporal and nasal) should be tested.

Question 7

What is the brainstem attachment and skull exit location of the oculomotor nerve (III)3?

Accepted Answer

Brainstem attachment: midbrain via interpeduncular fossa Skull exit: superior orbital fissure

Question 8

What is the brainstem attachment and skull exit location of the trochlear nerve (IV)4?

Accepted Answer

Brainstem attachment: midbrain on dorsal surface of brainstem Skull exit: superior orbital fissure

Question 9

What is the brainstem attachment and skull exit location of the abducens nerve (VI)6?

Accepted Answer

Brainstem attachment: pons Skull exit: superior orbital fissure

Question 10

What are the three divisions of the trigeminal nerve?

Accepted Answer

Opthalmic (V1) Maxillary (V2) Mandibular (V3)

Question 11

What do the sensory components of the trigeminal nerve supply?

Accepted Answer

Skin, teeth, mucous membranes of the face, anterior scalp and the dura.

Question 12

What do the motor fibres of the trigeminal nerve supply?

Accepted Answer

Four main muscles of mastication, number of others involved in swallowing, tensor tympani (dampens amplitude of vibration of tympanic membrane).

Question 13

Where are the cell bodies of (most of) the trigeminal sensory fibres located?

Accepted Answer

Trigeminal sensory nucleus

Question 14

Through which foramina do the three divisions of the trigeminal nerve exit the cranial cavity?

Accepted Answer

V1 - superior orbital fissure V2 - foramen rotundum V3 - foramen ovale

Question 15

Name the four autonomic ganglia of the face?

Accepted Answer

Submandibular Pterygopalatine Ciliary Otic

Question 16

Hanging from the pterygopalatine ganglion are two nerves: greater and lesser palatine. What do they supply?

Accepted Answer

Motor and sensory to the roof of the mouth, soft palate, tonsil, and lining membrane of the nasal cavity.

Question 17

How would you test the functioning of the sensory component of the trigeminal nerve?

Accepted Answer

Light touch is tested in each of the three divisions of the trigeminal nerve and on each side of the face using a cotton wisp or tissue paper. The ophthalmic division is tested by touching the forehead, the maxillary division is tested by touching the cheeks, and the mandibular division is tested by touching the chin. A common mistake is to use a stroking motion, which will trigger pain and temperature nerves. Instead, a point stimulus should be applied.

Question 18

Which two reflexes are tested when examining the trigeminal nerve?

Accepted Answer

Corneal reflex Jaw jerk reflex

Question 19

What is trigeminal neuralgia?

Accepted Answer

A neuropathic disorder characterized by episodes of intense pain in the face.

Question 20

List the four main muscles of mastication.

Accepted Answer

Masseter Temporalis Lateral pterygoid Medial pterygoid

Question 21

What division of the trigeminal nerve supplies the muscles of mastication?

Accepted Answer

Mandibular branch (V3)

Question 22

How would you test the functioning of the motor division of the trigeminal nerve?

Accepted Answer

Muscles of mastication (temporalis, masseter) should be inspected for atrophy. Palpate the temporalis and masseter as the patient clenches the jaw. The pterygoids can be tested by asking the patient to keep the mouth open against resistance, and move from side to side against resistance. A jaw jerk reflex can be tested by placing a finger over the patient's chin and then tapping the finger with a reflex hammer. Normally the jaw moves minimally.

Question 23

In a patients with unilateral damage to the motor root of the trigeminal, the jaw deviates to one side when opened against resistance. Does it deviate to towards the lesioned side or towards the intact side?

Accepted Answer

The mandible upon opening deviates toward the paralyzed side when there is unilateral paralysis of the masticatory muscles. This direction of the mandible is due to the action of normal pterygoids on the opposite side.

Question 24

What are the sensory functions of the facial nerve?

Accepted Answer

Sensory input from part of the external acoustic meatus and deeper parts of the auricle. Taste from the anterior two-thirds of the tongue.

Question 25

Where are the cell bodies of the sensory fibres running in the facial nerve located?

Accepted Answer

Nucleus solitarus

Question 26

What are the parasympathetic functions of the facial nerve?

Accepted Answer

Secretomotor activity in the lacrimal gland, submandibular and sublingual salivary glands, and glands in the mucous membranes of the nasal cavity, and hard and soft palates.

Question 27

What are the branches of the facial nerve?

Accepted Answer

``` Temporal Zygomatic Buccal Marginal mandibular Cervical. ``` (To zanzibar by motor car - superior to inferior)

Question 28

What is the function of the nerve fibres making up the chorda tympani?

Accepted Answer

The chorda tympani carries two types of nerve fibers: 1. Special sensory fibers providing taste sensation from the anterior two-thirds of the tongue (Facial nerve). 2. Presynaptic parasympathetic fibers to the submandibular ganglion, providing secretomotor innervation to two salivary glands: the submandibular gland and sublingual gland (facial nerve) and to the vessels of the tongue, which when stimulated, cause a dilation of blood vessels of the tongue.

Question 29

Chorda tympani carries fibres between the facial nerve and which other nerve? Why?

Accepted Answer

Involved in a very complex negative feedback loop with the lingual nerve.

Question 30

What is the function of the facial nerve fibres running in in the greater petrosal nerve?

Accepted Answer

Carries parasympathetic preganglionic fibers from the facial nerve, continues as the nerve of the pterygoid canal and ultimately synapses with the pterygopalatine ganglion whose parasympathetic postganglionic fibers synapse with the lacrimal gland and the mucosal glands of the nose, palate, and pharynx.

Question 31

What is Bell's palsy?

Accepted Answer

Bell's palsy is a form of facial paralysis resulting from a dysfunction of the cranial nerve VII (the facial nerve) causing an inability to control facial muscles on the affected side. Often the eye in the affected side cannot be closed.

Question 32

What is hyperacusis?

Accepted Answer

a health condition characterized by an increased sensitivity to certain frequency and volume ranges of sound (a collapsed tolerance to usual environmental sound). A facial nerve lesion may cause abnormal responses in the tensor tympani and stapedius muscles.

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SDL 1: Cranial nerves Flashcards

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