H&N 3: Cranial Nerve Overview #1

Question 1

List the cranial nerves

Answer 1

I - Olfactory
II - Optic 
III - Oculomotor 
IV - Trochlear 
V - Trigeminal 
VI - Abducens 
VII - Facial 
VIII - Vestibulocochlear
IX - Glossopharyngeal 
X - Vagus 
XI - Accessory 
XII - Hypoglossal

Question 2

Where do sensory fibres carry and take info?

Answer 2

• through peripheral branch into DRG

- then through central branch to dorsal horn

Question 3

What is function of dorsal root entry zone?

Answer 3

• afferent
• receives sensory info from periphery dep on type of info e.g. pain, proprioception etc to higher centres through thalamus

Question 4

What is function of ant. grey horn?

Answer 4

receives motor info from periphery

Question 5

What is contained in DRG?

Answer 5

Sensory cell bodies

Question 6

How can you perform actions?

Answer 6

• cell bodies in cerebral cortex in brain + corticospinal tract form many fibres from motor cortex going down to synapse at ventral horn of spinal cord
• then fibres go to muscles for movement

Question 7

What are the fibres in the head and neck?

Answer 7

• corticobulbar

- motor fibres synapsing on motor nuclei in brain stem of cranial nerves

Question 8

What type of fibres are motor + sensory?

Answer 8

• sensory: asc + dorsal

- motor: desc + ventral

Question 9

What links the CNS to the periphery?

Answer 9

• cranial & spinal nerves

Question 10

What do cranial & spinal nerves attach to?

Answer 10

• cranial nerves attach to forebrain + brain stem

- spinal nerves attach to spinal cord

Question 11

What are the features of cranial nerves?

Answer 11

• ganglia
• no synapses
• no DRG but gang of particular cranial nerve e.g. trigeminal ganglia
• have sensory/motor nuclei

Question 12

Where are I-IV located?

Answer 12

• ant. portion of the brain

- III from front of pons

Question 13

Where are V-VII arise?

Answer 13

• pons
• V from middle
• VI from back
• VII + VIII from cortico-pontine angle

Question 14

Where does VIII arise and go?

Answer 14

inner ear and goes to pons

Question 15

Where does IX-XII attach?

Answer 15

• medulla oblongata

- XII from pyramid

Question 16

What do asc + desc fibres of pons pass through?

Answer 16

• cortico-pontine angle

Question 17

What comes down the pyramid?

Answer 17

big cortico-spinal trunk

Question 18

What is optic chiasm?

Answer 18

where optic nerves cross over

Question 19

Describe 1st + 2nd order neurones

Answer 19

• synapse in CNS

- then sensory afferent in PNS

Question 20

Describe skeletomotor neurones

Answer 20

• cell bodies in CNS

- then somatic efferent (motor) to muscles

Question 21

Describe pre + postgang neurones

Answer 21

• synapse in CNS + PNS

- then somatic (visceral) to glands

Question 22

List special sensory/afferent only cranial nerves

Answer 22

I, II, VIII

Question 23

List efferent/motor only cranial nerves

Answer 23

III, IV, VI, XI, XII

Question 24

List afferent/efferent cranial nerves

Answer 24

V, VII, IX, X

Question 25

Which 4 cranial nerves have auto component?

Answer 25

- III, VII, IX, X | - carry 'cranial' part of craniosacral auto/para outflow from CNS

Question 26

What is functional component of cranial nerves?

Answer 26

- chewing + swallowing (tasting + smelling) - talking - looking - non-verbal comm (facial expression) - hearing

Question 27

Which areas give sensation by cranial nerves?

Answer 27

- cutaneous: scalp, face + neck - non-cutaneous: oral cavity (mucosa, teeth + tongue), cornea, nasal cavity + paranasal sinuses, pharynx, larynx, tympanic mem - articular: TMJ, cervical vert, atlantoocipital joint

Question 28

Which areas do cranial nerves give motor supply?

Answer 28

- muscles of facial expression - muscles of mastication - extra-ocular muscles - muscles of tongue - muscles of pharynx + larynx - cervical muscles

Question 29

What auto supply do cranial nerves also supply?

Answer 29

carry auto supply of glands + smooth muscle in ehead + neck

Question 30

Which reflexes are cranial nerves involved in?

Answer 30

- visual (pupillary, blink, accomm) - auditory - swallowing - gagging, vom - sneezing, coughing

Question 31

List functions of I-III

Answer 31

I - sensory fibres to nose for smell II - sensory fibres to eye for visual acuity, visual fields + ocular fundi II, III - Pupillary reactions

Question 32

Which nerves are involved in extra-ocular movements inc opening eyes?

Answer 32

III, IV, VI

Question 33

What is function of V?

Answer 33

- sensory supply to face for facial sensation - sensory supply for movements of jaw - corneal reflexes - motor supply to muscles of mastication

Question 34

What are functions of VII + VIII?

Answer 34

VII - facial movements + gustation (ant. 2/3 tongue) | VIII - hearing + balance

Question 35

What are functions of IX + X?

Answer 35

- swallowing - elevation of palate - gag reflex - gustation (post. 1/3 tongue)