Lecture 7 Cranial Nerves

Question 1

How many cranial nerves are there

Answer 1

12

Question 2

Somatic motor fibres supply what

Answer 2

Striated muscle (skeletal)

Question 3

Autonomic motor fibres supply what

Answer 3

Cranial division of parasympathetic innervates smooth muscle and glands

Question 4

Cranial nerves may contain

Answer 4

Somatic motor fibres
Autonomic motor fibres
Visceral sensory
General sensory
Special sensory fibres

Question 5

Visceral sensory fibres are

Answer 5

Afferent inputs from pharynx, larynx, heart, lung, gut

Question 6

General sensory fibres are

Answer 6

Afferent inputs (touch, temp, pain) from skin & mucous membranes

Question 7

Special sensory fibre are

Answer 7

Taste, smell, vision, hearing & balance

Question 8

What is the pathway of the olfactory nerve

Answer 8

nerve fibres pass through foraminifera in cribriform plate of ethmoid bone and enter olfactory bulb in the anterior cranial fossa

Question 9

What is the consequence of a fractured cribriform plate

Answer 9

May tear olfactory nerve fibres causing anosmia

Question 10

What is the pathway of the optic nerve

Answer 10

– enters via optic canal, nerves join to form optic chiasm, fibres from medial (nasal) half of each retina cross to form optic tract

Question 11

Increase in CSF pressure can lead to what

Answer 11

Papilloedema (optic disc swelling)

Question 12

Section of optic chiasma cut causes what

Answer 12

bitemporal hemianopsia

Question 13

What is the pathway of the oculomotor nerve

Answer 13

Emerges from midbrain and exits via superior orbital fissure

Question 14

Damage to the oculomotor nerve can cause what

Answer 14

– drooping of upper eyelid (ptosis)
– eyeball abducted and pointing down (Lateral deviation of the eye)
– no pupillary reflex
– no accommodation of the lens

Question 15

What is the pathway of the Trochlear

Answer 15

– emerges from dorsal surface of the mid brain and exits via the superior orbital fissure

Question 16

What does the trochlear nerve control

Answer 16

Superior oblique muscle

Question 17

What is the pathway of the trigeminal nerve V1

Answer 17

Emerges from the pons, travels through the trigeminal ganglion and exits via the superior orbital fissure

Question 18

What is the pathway of the trigeminal branch V2

Answer 18

– emerges from the pons, travels through the trigeminal ganglion and exits via the superior orbital fissure

Question 19

What is the pathway for the trigeminal branch V3

Answer 19

– emerges from the pons, travels through the trigeminal ganglion and exits via the foramen ovale

Question 20

What is the pathway of the abducent nerve

Answer 20

– emerges between pons and medulla and exits exits via the superior orbital fissure

Question 21

What happens when the abducent nerve is abnormal

Answer 21

Medial deviation of the affected eye causing double vision

Question 22

What is the pathway of the facial nerve

Answer 22

Emerges between pons and medulla and exits via internal acoustic meatus, facial canal and stylomastoid foramen

Question 23

What is the pathway of the vestibulocochlear nerve

Answer 23

– emerges from between pons and medulla and exits via internal acoustic meatus, dividing into vestibular & cochlear nerves

Question 24

What is the pathway of the glossopharyngeal nerve

Answer 24

Emerges from medulla and exits via jugular foramen

Question 25

What is the pathway of the vagus

Answer 25

– emerges from medulla and exits via jugular foramen, then everywhere!

Question 26

What is pathway of the accessory nerve

Answer 26

– small cranial (medulla)* and large spinal roots exit via jugular foramen

Question 27

What is the pathway of the hypoglossal nerve

Answer 27

– emerges from medulla and exits through the hypoglossal canal