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Neuro > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

semicircular canals

A

responds to head turning (angular acceleration)

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2
Q

what are the 2 otolith organs and what do you they respond to?

A

utricle and saccule

- respond to head positions and linear acceleration

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3
Q

One ______ and a number of ______ protrude from the top of the hair cells, and these get bent by the movement of the ______ during angular acceleration of the head. what does this cause?

A

kinocilium, stereocilia

  • cupula
  • change in membrane potential –> synapse with primary vestibular neurons
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4
Q

if your head turns to the right, the endolymph moves what direction?

A

left

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5
Q

the utricle and saccule (otolith organs) also contain hair cells, but instead of a cupula, on top of hair cells sits an ________ _______ which contains crystals of ______ _______

A

otolithic membrane

calcium carbonate

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6
Q

The utricle is positioned ________ with respect to the head, and the saccule is _______.

A

horizontal, vertical

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7
Q

what are the inputs to the vestibular nuclei? (4)

A
  1. primary vestibular neurons
  2. projections from flocculonodular lobe of cerebellum
  3. projections from spinal cord carrying information about posture and body orientation.
    These arrive directly as spinovestibular fibres (traveling with the posterior
    spinocerebellar tract) or indirectly via the cerebellum or reticular formation
  4. projections from contralateral vestibular nucle
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8
Q

what are the outputs of the vestibular system/ nuclei? (6)

A
  1. the cerebellum, providing information to aid equilibrium
  2. spinal cord (medial and lateral vestibulospinal tracts)
  3. thalamus and then from there information goes to the parietal lobe of the cortex, leading to conscious awareness of equilibrium and spatial orientation
  4. cranial motor nuclei of the extraocular muscles (oculomotor, trochlear, abducens), via the medial longitudinal fasciculus (MLF). This output is important for the vestibulo- ocular reflex (VOR).
  5. reticular formation including the center controlling vomiting
  6. contralateral vestibular nuclei
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9
Q

Lateral vestibulospinal tract

A

Efferent: the lateral vestibulospinal tract projects to all levels of ipsilateral spinal cord and leads to postural changes in response to body tilt

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10
Q

Medial vestibulospinal tract

A

Efferent: the medial vestibulospinal tracts project bilaterally to cervical spinal cord and are responsible for postural changes of neck muscles

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11
Q

the vestibulooccular reflex depends on what connections?

A

This reflex depends on the connections between the vestibular nuclei and the nuclei of the extraocular muscles via the medial longitudinal fasciculus

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12
Q

if the eyes move slowly to the left and then quickly back to the right, this is ______ nystagmus

A

right

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13
Q

Nystagmus can occur pathologically after vestibular lesions; if so, what way is the quick phase?

A

away from the side of the lesion

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14
Q

nystagmus can cause from damage to what?

A

medial longitudinal fasiculus (often targeted early in MS)

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15
Q

damage to the vestibular system could be caused by ? (5)

A
  1. Inner ear infection
  2. Toxic reaction to certain antibiotics (e.g. streptomycin, gentamycin).(in some cases can permanently damage hair cells)
  3. Traumatic head injury
  4. Stroke
  5. Meniere’s disease (caused by excess endolymph)
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16
Q

what is meniere’s disease caused by?

A

excess endolymph (or if the endolymph does not drain properly)

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17
Q

damage to the vestibular system could lead to?

A
  1. balance deficits, vertigo
  2. spontaneous nystagmus (pathological)
  3. involuntary rhythmic movements of one or both eyes at rest (horizontally, vertically, or rotary)
  4. impaired gaze stabilization
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18
Q

What is BPPV? (Benign Paroxysmal Positional Vertigo)

How can it be treated?

A
  • occurs when debris in one of the semi-circular canals (usually displaced otoliths from the utricle or saccule) leads to inappropriate firing of the vestibular nerve.
  • It can be treated by the Epley Maneuver, in which a series of head position changes lead to the debris being repositioned back into the utricle or saccule.
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19
Q

what does the Romberg sign indicate? how do you test for it?

A

damage to proprioceptive fibers

- ask patient to stand and close yes, if he loses balance this is a POSITIVE romberg sign

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20
Q

in order to stand and keep balanced you need two of?

A
  • vestibular input
  • vision
  • proprioceptive input
21
Q

the cerebellum integrates sensory and motor systems to influence: (6)

A
  1. balance and equilibrium
  2. muscle tone
  3. postural reflexes
  4. co-ordination
  5. fine motor control
  6. intrinsic (motor) learning
22
Q

climbing fibers receive input from ?

mossy fibers receives all other input, which includes? (4)

A
  • inferior olivary nucleus
    1. Axons from the vestibular nuclei
    2. Dorsal spinocerebellar tract
    3. Cuneocerebellar tract
    4. Corticopontocerebellar pathway (described below as part of the neocerebellar
    functional division)
23
Q

what does the inferior olivary nucleus play a role in?

A

role in error signals and motor timing

- inferior olivary nucleus catches the error and sends info to cerebellum

24
Q

what are the 4 deep cerebellar nuclei

A
  1. Dentate nucleus
  2. Interposed Nuclei (emboliform and globose)
  3. Fastigal Nucleus
25
Q

what are the 3 functional division of the cerebellum? and what are there roles

A
  1. vestibulocerebellum- postural responses to vestibular input
  2. neocerebellum- coordinationof voluntary movements
  3. spinocerebellum- muscle tone and postural control of the limbs
26
Q

damage to the flocculonodular lobe leads to?

and what are the symptoms? (3)

A 
medulloblastoma 
- truncal ataxia (difficulty walking)
- loss of equilibrium (balance) 
- staggering wide based gait 
(no tremor, and reflexes and m tone normal)
27
Q

how many fibers does the cerebral crus pathway contain?

how many go to the cerebellum ?

A

21 million (and only 1 million continue down the pyramids and 20 million go to cerebellum via pontine nuclei)

28
Q

damage to lateral posterior lobe of cerebellum causes what? what are the symptoms?

A
  • Neocerebellar syndrome
    1. hypotonia
    2. hyporeflexia
    3. problems with coordination of voluntary movements
  • take longer to initiate
  • problems stopping movements or changing direction
  • overshoot or undershoot targets (dysmetria)
  • intention tremor
  • rapid alternating movements especially difficult (dysdiadochokinesia)
  • jerky or slurred articulation of speech -(dysarthria)
29
Q

anterior lobe syndrome is caused by what? and causes what?

A

malnutrition from chronic alcoholism
(degeneration of cerebellar cortex starting at anterior end, bilaterally)
Causes:
- mainly effects legs - incoordination (ataxia) of leg movements
- broad based staggering gait

30
Q

what is Friedreich Ataxia ?

A

a genetic condition in which there is progressive degeneration of the PROPRIOCEPTIVE pathways (dorsal spinocerebellar and cuneocerebellar pathways, and dorsal columns pathway) as well as degeneration of the PYRAMIDAL system. There may also be cell loss in the cerebellum. Affected individuals typically have an ataxic gait and problems co- ordinating movements.

31
Q

the subthalamus is functionally connected to ? and structurally connected to?

A
  • basal ganglia

- continuous with midbrain tegmentum

32
Q

the thalamus forms part of the _____, _____ and ______ pathways

A

motor, sensory, limbic

33
Q

relay nuclei vs association nuclei

A

Relay nuclei receive well-defined fibers and project to specific areas of cortex. Association nuclei receive inputs from a variety of places and project to broad areas of association cortex

34
Q

damage to what thalamic nuclei has similar effects as a prefrontal lobectomy

A

medial dorsal (association nuclei)

35
Q

most damage to the thalamus is from what?

A 
vascular problems (sometimes tumors) 
- not often trauma because so deep in the brain
36
Q

damage to posterior thalamus leads to?

A
  1. Thalamic Pain Syndrome (contralateral to lesion): somatosensory stimuli causes pain, and other stimuli might be perceived abnormally.
  2. severe damage to VPM and VPL can lead to total loss of contralateral sensation (medial lemniscus pathway aka dorsal columns)
  3. which leads to Sensory Ataxia (loss of conscious proprioception)
37
Q

thalamic pain syndrome

A

a vague sense of pain but unable to localize it

- damage to posterior thalamus

38
Q

6 functions the hypothalamus is involved in

A
  • the control center of autonomic NS
  • temperature regulation
  • regulation fo food and water intake
  • emotion and behavior
  • control of circadian rhythms
  • sexual maturation and function
39
Q

the hypothalamus forms the floor of?

A

the 3rd ventricle

40
Q

what are the key structural features of the hypothalamus ?

A

Key structural features are the - mammillary bodies

  • tuber cinereum
  • neurohypophysis: median eminence, infundibular stalk and posterior lobe of pituitary gland.
41
Q

what structure does the pituitary gland attach to (where it gets ripped off)?

A

tuber cinereum (swelling below optic chiasm)

42
Q

what connects the hypothalamus and amygdala

A

the Stria Terminalis

43
Q

what are the 3 limbic system afferents of the hypothalamus?

A
  • septal area (reward and pleasure)
  • fornix (memory formation)
  • amygdala (emotion)
44
Q

4 neural inputs to hypothalamus

A
  1. brainstem (sensory info)
  2. frontal lobe
  3. midbrain reticular formation (sleep/wake cycle)
  4. limbic system
45
Q

two physical inputs of hypothalamus

A
  • sensitive to:
  • temperature
  • concentration of glucose and other hormones in bloodstream
46
Q

what are the hypothalamus efferents

A
  • septal area
  • hippocampus
  • amygdala
  • MD of thalamus
  • brainstem
  • reticular formation
47
Q

why will a lesion to the hypothalamus cause damage to more than one system?

A

Because the hypothalamus has large number of nuclei with different functions, all situated
in a small area

48
Q

damage to the hypothalamus produces a large number of symptoms that are grouped together and called what?
what are these symptoms?

A

hypothalamic syndrome

  • Sexual disorders: sexual retardation of precocity, impotence or amenorrhea
  • hyperthermia or hypothermia
  • obesity or wasting; eating disorders
  • diabetes insipidus (increased urine production)
  • disturbances of sleep
  • emotional disorders

Neuro (10 decks)

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