Cranial Nerves; Sensorimotor

Question 1

Name the cranial nerves

Answer 1

1) Olfactory,
2) Optic,
3) Oculomotor,
4) Trochlear,
5) Trigeminal,
6) Abducens,
7) Facial,
8) Vestibulocochlear,
9) Glossopharyngeal,
10) Vagus,
11) Spinal Accessory,
12) Hypoglossal

Question 2

Name the cranial nerves on the diagram below

Answer 2

Insert pic

Question 3

Where is the olfactory region?

Answer 3

The upper third of the nasal cavity. Superior to the superior nasal concha.

Question 4

Describe the travel of the olfactory nerves?

Answer 4

It passes through the cribriform plate and synapse at the olfactory bulb (which gets anchored by dura mater. From here, the nerves project to the olfactory cortex first and then to the limbic system, hypothalamus and reticular formation.

Question 5

What allows for the regeneration of olfactory neurons in adults?

Answer 5

The fact basal cells can differentiate into bipolar (olfactory) neurons.

Question 6

What is anosmia?

Answer 6

Loss of sense of smell which can be caused by an upper respiratory tract infection. or by trauma which can cause the brain and olfactory bulb to move which may tear the olfactory nerves

Question 7

What are some general features of the trigeminal nerve?

Answer 7

It has three divisions; V1 and V2 are afferent only and V3 which is both afferent and efferent. Supplies general, conscious sensation to most of the face, head and associated orbital and nasal and oral cavity. Has 4 nuclei and 2 roots, sensory roots to mesencephalic nucleus, pontine nucleus and spinal nucleus. Motor root which is from the motor nucleus.

Question 8

Name the divisions of the trigeminal nerve and their pathway

Answer 8

All emerge from trigeminal ganglion.
V1 - Ophthalmic division which travels along the lateral wall of the cavernous sinus through the superior orbital fissure to the orbit.
The maxillary division travels along the lateral wall of cavernous sinus through the foramen rotundum to pterygopalatine fossa.
Finally the mandibular division which travels through foramen ovale to infratemporal fossa

Question 9

What are the branches of the ophthalmic nerve

Answer 9

Gives off meningeal branch, but has three main branches; lacrimal, frontal and nasociliary.

Question 10

What are the functions of the lacrimal nerve?

Answer 10

Lacrimal nerve - supplies general sensation to lacrimal gland, conjunctiva and upper eyelid in the vicinity of lacrimal gland. Also carries PSNS fibres of facial nerve to lacrimal gland.

Question 11

What is the function of the frontal nerve?

Answer 11

It will divide into supra-orbital and supra-trochlear nerves, supply the upper eyelid and conjunctive, the frontal sinus and scalp as far back as vertex.

Question 12

What are the functions of the nasociliary nerve?

Answer 12

Gives off long ciliary nerves, anterior and posterior ethmoidal nerves before continuing as infratrochlear nerve. It will also give sensation to the cornea of eye and the tip of the nose

Question 13

What are the branches of the maxillary nerve?

Answer 13

It sends zygomatic and infra-orbital branches into the orbit via IOF. It also sends palatine and superior alveolar branches to the palate and upper teeth.

Question 14

What area does the maillary nerve supply?

Answer 14

• Lateral forehead,
• Zygomatic region,
• Lower lid,
• Sides of nose,
• Anterior cheek and,
• Upper lip

Question 15

What are the mandibular branches?

Answer 15

Auriculotemporal, masticatory, lingual and inferior alveolar banches.

(it is mixed sensory and motor)

Question 16

What area does the mandibular nerve supple?

Answer 16

Skin of auricle and temple,

• Posterior cheek,
• Lover lip section and chin,
• General sensation to anterior 2/3rds of the tongue,
• Teeth and lower gums

Question 17

What muscles does the mandibular nerve supply/

Answer 17

• Lateral pterygoid, medial pterygoid, masseter and temporalis (muscles of mastication)
• Tensor tympani,
• Tensor Veli Palatini,
• Mylohyoid,
• Anterior belly of digastric

Question 18

What nerve does the jaw jerk test?

Answer 18

The trigeminal nerve. What this does it when you tap the mental, both masseter and temporalis contract

Question 19

Describe the travel of the oculomotor nerve

Answer 19

-Runs anteriorly on lateral wall of cavernous sinus, passes through superior orbital fissure.. Divides into superior and inferior rami and then passes through common tendinous ring of Zinn

Question 20

Describe the travel of the trochlear nerve

Answer 20

• Nerve exits brainstem from posterior surface, runs anteriorly around cerebral peduncle, enters cavernous sinus, passses through superior orbital fissure and supplies superior oblique

Question 21

Injury to the trochlear nerve will cause?

Answer 21

Inability for patient to look medially and inferiorly

Question 22

Describe the travel of the abducent nerve

Answer 22

Nerve exits between pons and medulla, enters cavernous sinus, then enters orbit via superior orbital fissure to supply lateral rectus muscle.

Question 23

Injury to the abducent nerve would cause?

Answer 23

Inability to abduct the eye and horizontal diplopia

Question 24

What are features of the facial nerve motor nucleus?

Answer 24

it has superior and inferior divisions. Superior division is connected to ipsilateral and contralateral motor cortex. Will supply upper facial muscles
Inferior division is connected to only contralateral motor cortex. It will supply the lower facial muscles

Question 25

Describe the travel of the facial nerve

Answer 25

Emerges at cerebellopontine angle, enters skull via internal acoustic meatus, enters facial canal and gives off a nerve to strapedius and gives off chorda tympani. It then sends branches to supply occipitalis and auricular muscles. It enters the parotid gland and divides to form a plexus. It then gives off 5 branches; Temporal, zygomatic, buccal, mandibular and cervical branch.

Question 26

What occurs if their is damage to the facial nerve at the cerebellopontine angle?

Answer 26

• Balance and hearing problems,
• Ipsilateral facial muscle paralysis,
• Hyperacusis,
• Taste disturbances,
• Reduced lacrimal secretion

Question 27

What occurs if their is damage within the petrous temporal bone?

Answer 27

Reduced lacrimal secretion, hyperacusis, taste disturbances and ipsilateral facial muscle paralysis.

Question 28

What occurs if their is damage to the facial nerve distal to the stylomastoid foramen?

Answer 28

Ipsilateral facial muscle paralysis, dry eyes and drooling.

Question 29

What is the cornea reflex?

Answer 29

Involuntary blinking elicited by stimulation of the cornea - afferent via ophthalmic division of trigeminal nerve, efferent by facial motor nucleus

Question 30

What is the sensory input to the glossopharyngeal and the motor supply by the glossopharyngeal nerve.

Answer 30

Recives sensation from middle ear, oropharynx, palatine tonsil, inferior aspect of soft palate and posterior 1/3rd of tongue. Visceral sensation from carotid sinus and carotid body and taste from posterior 1/3rd of tongue.
Motor supply to stylopharyngeus muscle

Question 31

What sensory information does the vagus receive and what does it supply?

Answer 31

Recieves general somatic sensation from deep auricle and parts of external acoustic meatus, and general visceral sensation from laryngopharynx and larynx. Motor supply to striated muscles of pharynx and larynx.

Question 32

What are the efferent and afferent limbs of the gag reflex?

Answer 32

Afferent - Glossopharyngeal nerve,
Efferent - Motor nerve of vagus

Question 33

Describe features of the accessory nerve?

Answer 33

Has both spinal and sensory roots which exit the skull via jugular foramen. It crosses the posterior triangle. Supplies trapezius and sternocleidomastoid

Question 34

Describe features of the hypoglossal nerve

Answer 34

• Descends the neck and enters the oral cavity under the tongue to supply all tongue muscles except palatoglossus. If injured will cause ipsilateral tongue weakness, so tongue deviates to the side of the lesion.