Week 7 - The Cranial Nerves

Question 1

What are the 12 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. Accessory
12. Hypoglossal

Question 2

What is the function of CNI?

Answer 2

Olfactory - sense of smell

Question 3

What is the function of CNII?

Answer 3

Optic - sense of sight

Question 4

What is the function of CNIII?

Answer 4

Oculomotor - elevation of the upper eyelid and motor innervation of all the extraocular muscles except the superior oblique and lateral rectus muscles.

Innervates extraocular muscles:

• levator palpebrae superioris (elevation upper eyelid)
• inferior oblique (extorsion and elevation)
• superior rectus (elevation and intorsion)
• medial rectus (adduction)
• inferior rectus (intorsion and adduction)

Oculomotor - parasympathetic innervation via Edinger-Westphal nucleus in the Pupillary Light Reflex

Question 5

What is the function of CNIV?

Answer 5

Trochlear - motor innervation of the superior oblique muscle - intorsion and depression of the eye

Question 6

What is the function of CNVI?

Answer 6

Abducens - motor innervation of the lateral rectus muscle - abduction of the eye

Question 7

What are the 3 main divisions of the trigeminal nerve?

Answer 7

V1 - ophthalmic
V2 - maxillary
V3 - mandibular

Question 8

What is the function of CNV-1?

Answer 8

Ophthalmic - Trigeminal

Sensory innervation to the scalp and face above the lower eyelid

Question 9

What is the function of CNV-2?

Answer 9

Maxillary - Trigeminal

Sensory innervation to the face between the lower eyelid and upper lip

Question 10

What is the function of CNV-3?

Answer 10

Mandibular - Trigeminal
Sensory innervation to the face below the upper lip

Motor innervation to the muscles of mastication

Question 11

What is the function of CNVII?

Answer 11

Facial - motor, parasympathetic and sensory
Motor - muscles of facial expression

Parasympathetic - salivary glands - submandibular and sublingual
Parasympathetic - lacrimal glands

Sensory Taste - anterior 2/3 of the tongue
Sensory General - small area around the concha of the auricle

Question 12

What is the function of CNVIII?

Answer 12

Vestibulocochlear - sensory only
Vestibular organ - balance and detecting motion/position of the head
Cochlear organ - sense of hearing

Question 13

What is the function of CNIX?

Answer 13

Glossopharyngeal - motor, parasympathetic and sensory
Motor - stylopharyngeus muscle of pharynx

Parasympathetic - parotid gland (salivary gland)

Sensory Taste - posterior 1/3 tongue
Sensory General - posterior 1/3 tongue, oropharynx, carotid body and sinus, middle ear and Eustachian tube.

Innervates the oropharynx, carotid body and sinus, posterior 1/3 of the tongue, middle ear cavity and Eustachian tube.

Question 14

What is the function of CNX?

Answer 14

Vagus - motor, parasympathetic and sensory
Motor - majority of muscles of the larynx, pharynx and soft palate - i.e. speech and swallowing

Parasympathetic - smooth muscle of trachea, bronchi, GI tract and regulates heart rhythm (innervating cardiac smooth muscle)

Sensory - internal surfaces of laryngopharynx and larynx. visceral sensation to hollow viscera - heart, lungs, foregut and midgut (up to the distal-most part of the transverse colon).

Question 15

What is the function of CNXI?

Answer 15

Accessory - motor only

innervates trapezius and sternocleidomastoid muscles in the neck that allow movement of both the head and neck

Question 16

What is the function of CNXII?

Answer 16

Hypoglossal - motor only
innervates the intrinsic and extrinsic muscles of the tongue (except - palatoglossus)
allows movement of the tongue relative to itself

Question 17

What foramina does each of the cranial nerves pass through?

Answer 17

olfactory - foramina of the cribiform plate
optic - optic canal 
oculomotor - superior orbital fissure
trochlear - superior orbital fissure
trigeminal ophthalmic - superior orbital fissure
trigeminal maxillary - foramen rotundum 
trigeminal mandibular - foramen ovale 
abducens - superior orbital fissure
facial - internal acoustic meatus 
vestibulocochlear - internal acoustic meatus 
glossopharyngeal - jugular foramen 
vagus - jugular foramen 
accessory - jugular formaen 
hypoglossal - hypoglossal canal

Question 18

What cranial nerve nuclei are associated with the oculomotor nerve?

Answer 18

oculomotor nucleus - midbrain - motor innervation of extraocular muscles and upper eyelid
Edinger-Westphal nucleus - midbrain - parasympathetic innervation through pupillary light reflex

Question 19

What cranial nerve nuclei are associated with the trochlear nerve?

Answer 19

trochlear motor nucleus - midbrain - motor innervation of superior oblique extraocular muscle

Question 20

What cranial nerve nuclei are associated with the abducens nerve?

Answer 20

abducens motor nucleus - pons - motor innervation of lateral rectus muscle

Question 21

What cranial nerve nuclei are associated with the vestibulocochlear nerve?

Answer 21

vestibulocochlear nucleus - pons - divided into larger vestibular and smaller cochlear nuclei giving sense of balance, motion of head and hearing

Question 22

What cranial nerve nuclei are associated with the accessory nerve?

Answer 22

accessory motor nucleus - medulla oblongata/cervical portion of spinal cord - motor innervation of trapezius and sternocleidomastoid muscles

Question 23

What cranial nerve nuclei are associated with the hypoglossal nerve?

Answer 23

hypoglossal motor nucleus - medulla oblongata - motor innervation of intrinsic and extrinsic muscles of the tongue (except - palatoglossus)

Question 24

What cranial nerve nuclei are associated with the trigeminal nerve?

Answer 24

Motor nucleus of trigeminal nerve - located in upper portion of pons, medial to sensory trigeminal nucleus - linked to mandibular division which innervates muscles of mastication

Sensory nucleus of trigeminal nerve - large and extends from the cerebral peduncles of the midbrain to the medulla and upper portion of the spinal cord - sensory innervation of the face
It has three parts - upper: mesencephalic nucleus / middle: principal nucleus / lower: spinal nucleus

spinal trigeminal sensory nucleus also associated with facial, glossopharyngeal and vagus cranial nerves.

Question 25

What cranial nerve nuclei are associated with the facial nerve?

Answer 25

Facial Motor Nucleus - found in the pons, anterolateral to the abducens nerve - muscles of facial expression

Superior Salivary Nucleus - in the pons - parasympathetic innervation of lacrimal, sublingual and submandibular glands

Spinal Trigeminal Sensory Nucleus - extending from the pons into the medulla and upper portion of cervical spinal cord - general sensory innervation to area around the concha of the auricle

Nucleus of the Solitary Tract - special sensory innervation - taste anterior 2/3 tongue

Question 26

What cranial nerve nuclei are associated with the glossopharyngeal nerve?

Answer 26

Nucleus Ambiguus - found in medulla, lying deep to the reticular formation - motor innervation to stylopharyngeus muscle of pharynx

Inferior Salivary Nucleus - in the pons below the superior salivary nucleus - parasympathetic innervation of parotid gland

Nucleus of the Solitary Tract - important role in reflex control of cardiovascular and respiratory functions

Nucleus of the Solitary Tract - special sensory innervation - taste posterior 1/3 tongue

Spinal Trigeminal Sensory Nucleus - general sensory innervation of posterior 1/3 tongue, oropharynx, carotid body and sinus, middle ear and Eustachian tube.

Question 27

What cranial nerve nuclei are associated with the vagus nerve?

Answer 27

Nucleus Ambiguus - found in medulla, lying deep to the reticular formation - motor innervation to majority of muscles of the larynx, pharynx and soft palate

Dorsal Motor Vagus Nerve - parasympathetic innervation of smooth muscle of trachea, bronchi, GI tract and regulates heart rhythm (innervating cardiac smooth muscle)

Nucleus of the Solitary Tract - special sensory innervation - tongue (root/epiglottis portion) and visceral sensation to heart, lungs, foregut and midgut

Spinal Trigeminal Sensory Nucleus - general sensory innervation to posterior ear, external auditory meatus, and posterior and external surface of tympanic membrane