Lecture 8

Question 1

Name for primary olfactory cortex

Answer 1

Uncus

Question 2

Path of smell from nose to brain

Answer 2

Primary sensory neuron in nose - olfactory bulb via. olfactory nerve - olfactory tract to uncus (bypassing thalamus) - amygdala/hippocampus/hypothalamus

Question 3

Where does the hypoglossal nerve (CN XII) exit the cranial cavity from?

Answer 3

Hypoglossal canal

Question 4

What nerves exit the cranial cavity from the internal acoustic meatus? (2)

Answer 4

CN VII Facial nerve
CN VIII Vestibulocochlear nerve

Question 5

What nerves exit the cranial cavity from the superior orbital fissure? (4)

Answer 5

CN III Oculomotor nerve
CN IV Trochlear nerve
CN V1 Trigeminal nerve ophthalmic division
CN VI Abducens nerve

Question 6

CN V divisions, and where they exit the cranial cavity (3)

Answer 6

V1 (Ophthalmic) - superior orbital fissure
V2 (Maxillary) - foramen rotundum
V3 (Mandibular) - foramen ovale

Question 7

Which nerves exit the cranial cavity through the jugular foramen (3)

Answer 7

CN IX Glossopharyngeal nerve
CN X Vagus nerve
CN XI Spinal accessory nerve

Question 8

Genioglossus - which CN innervates it, function, and lesion effect

Answer 8

Innervated ipsilaterally by CN XII (Hypoglossal)
Muscle that pushes tongue to the center - muscle on both sides = tongue sticks out
Tongue deviates to the same side as the lesion

Question 9

CN innervation for touch of anterior 2/3 of tongue

Answer 9

CN V3 Trigeminal nerve mandibular division

Question 10

CN innervation for taste of anterior 2/3 of tongue

Answer 10

CN VII Facial nerve - chorda tympani ‘hitchhikes’ on lingual nerve of CN V to tongue (cell bodies at geniculate ganglion)

Question 11

CN innervation for touch and taste of posterior 1/3 of tongue (and branches), and where are their cell bodies found

Answer 11

CN IX Glossopharyngeal nerve (tonsillar and lingual branches go to palatine tonsil and tongue, respectively, cell bodies at inferior ganglion)

Question 12

Taste pathway (3 neuron pathway) from tastant to brain & collateral branches

Answer 12

Tastants activate taste buds that activate CN VII or IX Synapse at NTS
Synapse at VPM (ventral posteromedial nucleus)
3rd order neuron projects to gustatory cortex
Collateral branches to amygdala hippocampus

Question 13

CN involved in hearing/balance (3)

Answer 13

CN VIII Vestibulocochlear nerve
CN VII Facial nerve - stapedius m. (stapes)
CN V3 Trigeminal nerve - tensor tympani m. (malleus)

Question 14

Ganglion for cochlear nerve and vestibular nerve

Answer 14

Vestibular ganglion and spiral ganglion in cochlea

Question 15

High frequency sounds vibrate closer to the ___
Low frequency sounds vibrate closer to the ___
(higher frequency = higher pitch)

Answer 15

Closer to the oval window
Closer to the apex

Question 16

Auditory pathway (3 neuron bilateral pathway) from CN VIII to primary auditory cortex

Answer 16

CN VIII to medulla
Synapses at dorsal & ventral cochlear nuclei
Neurons decussate, stay ipsilateral, or go to superior olivary complex (works with inferior complex)
Travel through inferior colliculus in midbrain (reflex to turn head to where sound is)
Synapse at MGN of thalamus

Question 17

Role of facial and trigeminal nerve (mandibular branch) in hearing

Answer 17

Contract stapedius and tensor tympani to dampen loud sounds

Question 18

Components of vestibular system

Answer 18

Utricle, saccule, and 3 semicircular canals

Question 19

Ampulla and cupula

Answer 19

Ampulla - swellings at the base of the semicircular canals
Cupula - receptor organ in semicircular canal that deflects with head movement, moving hair cells that turn an action potential on or off

Question 20

Vestibule

Answer 20

Area between the cochlea and semicircular canals, contains the utricle and saccule

Question 21

Maculae (ear)

Answer 21

Sensory ‘organs’ of the utricle and saccule, contain an otolithic membrane embedded with otoliths (calcium carbonate crystals)

Question 22

How do otoliths stimulate CN VIII

Answer 22

Otoliths cause the hair cells to bend which stimulates CN VIII - saccule for vertical, utricle for horizontal

Question 23

Where do the utricle & saccule vs. semicircular canals project to

Answer 23

U & S - to vestibulospinal system
Semicircular canals - to vestibulo-ocular system

Question 24

Lateral and medial vestibulospinal tract (2 neuron reflex)

Answer 24

CN VIII to caudal pons/rostral medulla
Synapse at vestibular nuclei
Lateral VS tract - ipsilateral, acts on LMN limbs to contract extensors and relax flexors (extend limbs)
Medial VS tract - bilateral to LMN axial muscles