H&n B4: General Somatic, Auditory, Vestibular Pathways

Front 1

How does sensation from the face, head, and neck travel back to the CNS?

Back 1

PRIMARILY through trigeminal nerve. Small areas of skin/viscera use facial, glossopharyngeal, vagus nerves.

Front 2

3 nuclei in the brainstem associated with the trigeminal system:

Back 2

1) Mesencephalic nucleus of V
2) Principal (pontine/chief) sensory nucleus
3) Spinal trigeminal nucleus - divided into nucleus oralis, nucleus interpolaris, nucleus caudalis

Front 3

Nucleus oralis, nucleus interpolaris, and nucleus caudalis are divisions of the _____ nucleus. What senses do each ones carry?

Back 3

Spinal nucleus.

Nucleus caudalis - touch, pain, termperature

Nucleus oralis - pain impulses from tissues of oral cavity

Nucleus interpolaris - not known

Front 4

List the ganglion associated and areas of sensory representation for

1) Trigeminal nerve
2) Facial nerve
3) Glossopharyngeal nerve
4) Vagus nerve

Back 4

1) Trigeminal ganglion, aka Gasserian/semilunar.
1a) Mario Smushed TOAD's Mushroom Cart

Membranes of nose/nasal cavity
Skin of face/forehead/scalp
TMJ
Oral cavity/teeth
Anterior 2/3 of tongue
Dura surrounding brain (majority)
Maxillary/frontal sinuses
Cornea/conjunctiva

2. Geniculate ganglion
2a) Everyone Clapped.

External auditory meatus
Conchae of ear

3. Superior ganglion of IX
3a) Princess Peach, Arriving Last

Pharynx (upper portion)
Posterior 1/3 of tongue
Auditory tube (upper portion)
Lateral aspect of ear (small area)

4) Superior ganglion of X

Didn't Take Losing Politely & Cried Everywhere

Dura of posterior cranial fossa
Tympanic membrane
Lower larynx and pharynx
Posterior wall/floor of external auditory meatus
Conchae of the ear
Esophagus (upper portion)

Front 5

Describe the sensory pathway for crude touch, pain, and temperature in the head.

Back 5

Fibers from cell bodies in the ganglia descend in the spinal tract of V -> synapse in nucleus caudalis (2nd order neurons) -> Travel up in ventral trigeminothalamic tract to contralateral thalamus (3rd order neurons) -> thalamus to somatosensory cortex of parietal lobe of the cerebrum

Front 6

1. Damage to the spinal tract of V results in?

2. Damage to the trigeminothalamic tract results in?

Back 6

1. Ipsilateral sensory loss to the face and contralateral sensory loss in the remainder of the body (alternating hemianesthesia)

2. Contralateral sensory loss in the face

Front 7

1. Where are cell bodies associated with tactile discrimination and pressure located?

2. Describe the pathway for these sensations.

Back 7

1. Trigeminal (Gasserian, semilunar) ganglion.

2. Fibers from trigeminal ganglion -> synapse in principal sensory nucleus of V (second order) -> ascend bilaterally in dorsal ascending tract of V -> thalamus (third order neurons) -> somatosensory cortex

Front 8

1. Where do fibers for proprioception come from in the head?

2. Why is the proprioceptive pathway unique?

3. Describe the proprioceptive pathway

Back 8

1. Trigemino-proprioceptive fibers come from muscles of mastication, TMJ, and periodontal ligament around the teeth.

2. Cell bodies not found in ganglion. Found in nucleus in the midbrain (mesencephalic nucleus of V)

3. Fibers from TMJ/muscles of mastiaction/periodontal ligament around teeth -> mesencephalic nucleus of V -> motor nucleus of V

This forms a reflex loop.

Fibers from mesencephalic loop may also go bilaterally to thalamus and cerebellum.

Front 9

Describe the auditory pathway, starting from the middle ear.

Back 9

Middle ear -> inner ear -> hair cells in cochlea -> spiral ganglion in temporal bone -> auditory part of vestibulocochlear nerve -> left and right cochlear nuclei

Ventral cochlear nuclei -> superior olivary nucleus (pons) -> inferior colliculus -> medial geniculate nucleus (thalamus) -> auditory cortex

Dorsal cochlear nuclei -> inferior colliculus -> medial geniculate body (thalamus) -> auditory cortex

Front 10

What is the pathway of the startle reflex?

Back 10

Inferior colliculus -> autonomic motor centers

Front 11

What is the auditory radiation?

Back 11

Thalamus -> temporal gyrus pathway

Front 12

What are the two primary portions of the vestibular system?

Back 12

Vestibulocochlear nerve + peripheral connections, cerebellum.

Front 13

Describe the pathway of the vestibular system.

Back 13

Hair cells -> vestibular ganglion (inside internal acoustic meatus) -> vestibulocochlear nerve -> axons terminate on vestibular nuclei (medulla) -> inferior cerebellar peduncle -> cerebellum -> flocculonodular lobe -> the fastigial nucleus of the cerebellum -> bilaterally to vestibular nuclei on ipsilateral and contralateral side of original input (cerebellar-vestibular feedback) -> lateral vestibular nucleus descends ipsilaterally in lateral vestibulospinal tract to synpase on anterior horn cells, superior, medial, and inferior descend ipsilaterally/contralaterally in medial vestibulospinal tract to synpase on anterior horn cells.

Front 14

What is the receptor organ of the inner ear composed of?

Back 14

Utricle and sacculus (two fluid filled sacs), endolymph, and hair cells.

Front 15

Describe the vestibulo-ocular tracts

Back 15

Receptor cells in semicircular canals -> impulses to vestibulocochlear nerve -> ganglion fibers synapse on vestibular nuclei -> travel bilaterally in medial longitudinal fasciculus to oculomotor, trochlear, abducens nuclei.

Front 16

How is the mesencephalic nucleus of V special?

Back 16

*does not involve gussarian ganglion
* only nucleus in the brainstem where you have no synapses in a ganglion
*nucleus does not go up the thalamus

Front 17

When dura is compressed, you can get vomiting and nausea. What nerves primarily carry these sensations?

Back 17

Vagus and trigeminal.

Front 18

What are the 4 causes of true visceral pain?

Back 18

1) Ischemia (lack of blood supply)
2) Chemical stimuli (burns)
3) Spasm of hollow viscus
4) Overdistension of a hollow viscus

Front 19

What are disorders that can cause pain that is thought to be from the TMJ?

Back 19

1) Intracranial lesions (brain tumors of vascular abnormalities)
2) Extracranial lesions (tumors/infections of parotid gland, orbit, ear)
3) Rheumatic or athritic conditions
4) Vascular conditions
5) Myofascial disorders
6) Causalgia
7) Neurogenic conditions (neuritis, neuralgia)
8) Psychogenic problems
9) Cranial arteritis
10) Acoustic neuroma
11) Trigeminal neuralgia

Front 20

What is causalgia?

Back 20

Reflex sympathetic dystrophy - continuous intense pain out of proportion to severity of initial injury

Front 21

What is an acoustic neuroma? What causes it? What are the symptoms?

Back 21

Radiating pain from mandible, twitching, lack of balance. Facial nerve and vestibulocochlear nerve exit skull through internal acoustic meatus, acoustic neuroma is a slow growing tumor in that area.

Front 22

What is tic douloureux? What nerves is it associated with?

Back 22

Trigeminal neuralgia - pain in the face that it is horrible. Primarily associated with maxillary and mandibular branches of cranial nerve V

Front 23

If you have a strong enough force that can blow out the tympanic membrane, why can you lose taste too?

Back 23

Branch of facial nerve that carries taste from the anterior 2/3 of the tongue is called chorda tympani, and it runs with the tympanic membrane. You can blow both of these out and lose both hearing and taste from the anterior 2/3 of the tongue.

Front 24

If a lady is repeatedly hearing a song when there is no sound around, where could she have a tumor?

Back 24

Superior temporal gyrus - involved with hearing, memory of hearing, perception of hearing, and interpretation.

Front 25

What two parts of the brain are involved in balance?

Back 25

Brainstem and cerebellum

Front 26

If you're spinning drunkenly, how do you get nystagmus?

Back 26

You're messing with the vestibular nuclei, which are sending bilateral axons up to the oculomotor, abducens, and trochlear nuclei. Your eyes start spinning left and right.

Front 27

How do ice skaters not get sick when they spin?

Back 27

They focus on one spot - sends feedback to vestibular nuclei that you're not spinning, overrides barfing mechanism.