SSA And Cerebellum

Question 1

What are the special visceral afferent (SVA) neurons??

Answer 1

Smell and taste

CN I
CN VII, IX, X

Question 2

What are the special visceral efferent neurons?

Answer 2

Supply motor innervation to muscles of pharyngeal arch

CN V, VII, IX, X, and XII

Question 3

What are the special somatic afferent (SSA) neurons??

Answer 3

Vision. Hearing and balance

CN II
CNVIII

Question 4

The _________ retinae receives light from the peripheral visual fields. Do these axons cross at the optic chiasm?

Answer 4

Nasal ; yes

Question 5

The __________ retinae receives light from the binocular vision field. Do these axons cross over at the optic chiasm?

Answer 5

Temporal; no

Question 6

How do visual fields differ in predator and prey animals

Answer 6

Prey- eyes more laterally placed, have wide peripheral vision

Predator- eyes more rostral; overlapping visual field increase depth perception

Question 7

What is the site where optic nerves cross?

Answer 7

Optic chiasm

Question 8

Optic tracts synapse onto the __________________ of the thalamus

Answer 8

Lateral geniculate body

Question 9

Neurons within the optic tract can project to where?

Answer 9

Thalamus -> (primary visual pathway) conscious

Midbrain-> unconscious

Question 10

What is the primary visual pathway?

Answer 10

Nasal and temporal retina
Optic nerve
Optic chiasm -> nasal retinae cross over; temporal retinae remain ipsilateral
Optic tract
Lateral geniculate nucleus (thalamus)
Optic radiation (component of internal capsule)
Occipital cortex

Question 11

Once in the visual cortex, where can visual information be directed?

Answer 11

Contralateral visual cortex via corpus callosum

Bilateral motor fortifies (frontoparietal)

Cerebellum via pons

Tectum/rostral colliculus

Tegmentum

Nuclei of crainial nerves III, IV, VI via rostral colliculus

Question 12

What is the pathway of the menace response?

Answer 12

Primary motor pathway to occipital lobe -> motor cortex via internal capsule -> pons and cerebellum -> facial nuclei -> facial nerve-> orbcularis oculi m.

Question 13

A small percentage of optic tracts for unconscious reflex travel and synapse at what two nuceli?

Answer 13

Pretectal nuceli (at junction of midbrain and thalamus)

Rostral colliculi (tectal nuceli)

Question 14

In pupillary light reflex and visual accommodation, what nuceli does the optic tract synapse to?

Answer 14

Pretectal nuceli

Question 15

In somatic motor responses of the eye what nuclei does the optic tract synapse to?

Answer 15

Rostral colliculi (tectal nuclei)

Question 16

What is the pathway for pupillary contraction?

Answer 16

Optic nerve -> optic chiasm -> optic tract -> pretectal nuclei (ipsilateral and contralateral) ->PSNS oculomotor nucleus -> oculomotor nerve -> ciliary ganglion -> constrictor muscle

Question 17

What is the pathway of pupillary dilation ?

Answer 17

Optic nerve -> optic chiasm -> optic tract -> rostral colliculus nuclei -> descend in lateral horn (sympathetic =throacolumbar) -> cervical sympathetic chain -> crainal cervical ganglion -> dilator muscle

Question 18

Tectobulbar axons and tectospinal axons both arise from the rostral colliculus. What cranial nerves do each of these axon tracts influence ?

Answer 18

Tectobulbar –> eye movement
CN III, IV, and VI

Tectospinal –> head movement
CN XI

Question 19

Circadian rhythms us the ___________ pathway. Stimulated by dark/night the pineal gland releases _____________

Answer 19

Retinohypothalmic; melatonin

Pineal gland is sympathetic innervated -> must descend to thoracic level and ascend back to the superficial cervical ganglion before stimulating the pineal gland

Question 20

What stimulates the cochlear afferent neuron?

Answer 20

Movement of stapes at vestibular window > displace perilymph -> defect cochlear hairs (mechanoreceptor ) -> cochlear neurons

Question 21

Where are the cell bodies of the cochlear neuron (SSA) located>

Answer 21

Spinal ganglia

Question 22

What is the conscious auditory pathway?

Answer 22

Cochlear nerve -> spiral ganglia -> cochlear nuceli (medulla) -> caudal colliculus -> medial geniculate nucleus (thalamus) -> internal capsule -> auditory cortex

Question 23

The hearing reflex pathway goes through what nuclei to what tract?

Answer 23

Caudal colliculus -> tectospinal tract –> motor neurons

Question 24

A reflex elicited by a sudden onset of tactile, vestibular, or acoustic stimuli that exceeds a certain intensity threshold

Answer 24

Startle reflex

Question 25

In a startle reflex, descending pathways of the tectospinal tract causes?

Answer 25

Flexion of almost all skeletal muscle

Question 26

What type of hearing loss results because of damage to structures of external or middle ear preventing conduction of sound waves to the internal ear?

Answer 26

Conductive hearing loss

Question 27

What type of hearing loss results due to damage of structures of the inner ear preventing stimulation of electrical impulses or due to damaged central nuclei/pathways

Answer 27

Sensorineural

Question 28

Organ that senses balance and acceleration and aids in maintaining stable orientation relative to gravity

Answer 28

Vestibular organ

Question 29

What motor pathways does the vestibular organ influences

Answer 29

Position of eyes, neck, trunk, and limbs relative to movement of head

Question 30

What are the vestibular organs?

Answer 30

``` Maculae (utricli and sacculi) Cristae ampulares (semicircular canals) ```

Question 31

Where are the cell bodes of the vestibular organs (SSA) located?

Answer 31

Vestibular ganglia

Question 32

What are the three vestibular pathways?

Answer 32

Ascending medial longitudinal fasciculus (brainstem) -> control eye movement Vesibulospinal tract -> cerebellum to adjust posture and balance Thalamocortical pathway -> thalamus -> cortex for conscious perception of balance

Question 33

What is the overall effect of stimulation of the vestibular organ?

Answer 33

Goes to vestibular nuclei -> spinal cord -> Ipsilateral : inhibit flexors and stimulate extensor Contralateral: inhibit extensor Prevents falling

Question 34

A lesion the the left vestibular organ/pathway will make the animal feel like there is movement to the _________________ side. To compensate, the animal will move their poster and balance to the ________ side.

Answer 34

Right (away from lesion) ;left (toward lesion) LEFT lesion: feel right, go left

Question 35

The _____________reflex produces neck and forelimb movement that counteracts the tilt of the head

Answer 35

Vesibulocollic

Question 36

A lesion to the RIGHT vestibulocollic pathway causes the animal to feel movement toward the ___________ side. The animal will counteract this by tiling the head to the __________

Answer 36

Left; Right RIGHT lesion: feel left, go right

Question 37

Describe the vestibule-ocular reflex

Answer 37

Eye maintains a fixed position while the head moves Head movement toward any side will stimulate vestibular organ on that side -> both eyes move in opposite direction to maintain position (compensatory) -> eyes rapidly move in same direction as head rotation for new focus point

Question 38

What is physiological nystagmus?

Answer 38

Normal movement of the eyes in response to head movement First in opposite direction (slow phase) followed by fast phase movement toward direction of head turn

Question 39

Rapid movement of the eyes when the head is not moving or when the body changes position

Answer 39

Resting/positional nystagmus NOT normal -> vestibular problems Slow phase followed by fast phase

Question 40

In a peripheral vestibular disorder, the fast phase nystagmus is (toward/away) the side of the lesion and the slow phase it (toward/away) the side of lesion ?

Answer 40

In a peripheral vestibular disorder, the fast phase nystagmus is AWAY from the side of the lesion and the slow phase it TOWARD the side of lesion

Question 41

What nystagmus can be present with disorders of the central vestibular system?

Answer 41

Horizontal, vertical, or rotary Peripheral vestibular disorders-- only horizontal or rotary

Question 42

A peripheral disorder of the vestibular system can be a lesion in the ?

Answer 42

Vestibular receptors

Question 43

A central vestibular disorder can result from lesions in the ?

Answer 43

Vestibular ganglion CN VIII Vestibular nuclei

Question 44

Excessive stimulation of the vestibular system to the ______ center causes nausea

Answer 44

Emetic center Eg motion sickness

Question 45

The cerebellum is made up of a __________, located between right and left hemispheres

Answer 45

Vermis

Question 46

What is located on the ventral cerebellum and is the major pathway of communication with he vestibular nuclei?

Answer 46

Flocculonodular lobe

Question 47

What is the main function of the cerebellum>?

Answer 47

Determine rate, range and force of movements Does NOT initiate movement --> frontal lobes job

Question 48

Afferents project to the cerebellum cortex and cerebellar nuclei via what tracts?

Answer 48

Cerebellar peduncles

Question 49

What 4 afferent pathways can project to the cerebellum

Answer 49

General proprioception (spinocerebellar) Special proprioception (vesibulocerebellar) Special somatic (tectocerebellar) UMN (extrapyramidal)

Question 50

Efferent from the cerebellum can project through the cerebellar peduncles to what three nuclei?

Answer 50

Vestibular nuceli (spinal cord- vesibulospinal tract) Reticular formation (cerebral cortex) Extrapyramidal nuceli (motor cortex)

Question 51

The _____________ cerebellar peduncles communicates from the spinal cord to the cerebellum containing mostly primarily afferent neurons

Answer 51

Caudal

Question 52

The ___________ cerebellar peduncle is a tract from the pons to the cerebellum containing entirely afferent fibers

Answer 52

Middle

Question 53

The ________ cerebellar peduncle is a tract from the cerebellum to the mesencephalon (midbrain) containing mainly efferent fibers

Answer 53

Rostral

Question 54

On the brainstem, the cerebellar peduncles are found in what order from medial to lateral?

Answer 54

Rostral, caudal, middle

Question 55

___________ species have early cerebellum development and can get up soon after birth

Answer 55

Precocial

Question 56

______________ species have a longer development of the cerebellum and develop their motor skills, coordinator, and senses later

Answer 56

Altricial

Question 57

Cerebellar disease causes?

Answer 57

Inadequate/inappropriate motor response | Incoordination

Question 58

What are the three types of ataxia?

Answer 58

Cerebellar Proprioceptive Vestibular

Question 59

Cerebellar ataxia has what signs

Answer 59

Dysmetria -inability to judge distance or force Hypermetria -overmeasurement of gait Burst effect of movement because it is delayed and exaggerated response Wide-based stance, intention tremors, truncal sway, delay onset of menace response

Question 60

Cerebellar ataxia can be due to lesions where?

Answer 60

Cerebellar cortex Cerebellar peduncles Cerebellar nuclei