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neuro exam 3 > descending pathways > Flashcards

descending pathways Flashcards

1
Q

motor system evolution

A

-as animals evolved with more complex nerous systems and motor capabilities more pathways evolved

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2
Q

steps of motor system evolution

A
  • reticular formation
  • vestibular system
  • development of tectum
  • development of red nucleus
  • development of cerebral cortex to control the above systems
  • then the devlopment of the pyramidal tract
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3
Q

how are the descending pathway neurons of the limbs organized in the ventral horn
- example

A
  • somatotopic organization
  • more medial you are in the spinal cord the more medial the muscles are
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4
Q

what are the 2 groups of descending pathways

A

lateral ( lateral cortico spinal tract) and medial pathways ( vestibulo spinal tract, reticulospinal, tectospinal)

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5
Q

why are the lateral cortico spinal tract lateral?

A

◼ Control of distal musculature
- such as hands and fingers

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6
Q

why are vestibulo spinal , reticulospinal, and tectospinal tracts medial

A

◼ Control of axial and proximal
musculature
- such as balance and equilibrium

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7
Q

what cells are located in the cortex

A

Giant pyramidal cells
- (betz cells)

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8
Q

when does the motor cortex fire

A

Fires impulses prior to muscle
movement

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9
Q

how is the motor cortex organized to produce

A

◼ Organized to produce simple
movements of individual body parts

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10
Q

what does the motor cortex determine

A

Determines direction, amplitude,
speed, and force of movement

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11
Q

the motor cortex is not organized to control ______ muscles

A

individual

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12
Q

what is the somatotopic organization of of the primary motor cortex

A

More area given to parts of body that perform
more precise and delicate movements as compared
to those that perform less precise movements.

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13
Q

what is the efferent patheay

A

pathway:
-axons travel through white matter  internal capsule
 cruscerebri/cerebral peduncle
 pyramidal fibers pierce the pons  pyramids of medulla
 lateral
corticospinal tract

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14
Q

where is the the crus ceribri and sunstantia ( cerbral peduncle )

A
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15
Q

where are the pyranidal fibers in the pons ( cortical spinal tract)

A
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16
Q

what does the premotor cortex produce movements in response to
- what types of movements does it direct?

A
  • visual and other stimuli
  • Directs reaching and grasping
    movements
17
Q

what is the supplementary motor cortex concerned with

A

Concerned with movement that is
self- generated

18
Q

what is included in the motor asscocaiation cortex

A
  • premotor cortex
  • supplementary motor cortex
19
Q

photo of premotor and primary motor cortex

A
20
Q

what is the corticobulbart tract pathway

A

◼ Cell bodies in motor cortex (lateral
convexity)
◼ Fibers leave through internal capsule
◼ Exit in midbrain, pons and medulla
◼ Innervate cranial nerve motor nuclei
◼ Crossed and uncrossed fibers

21
Q

what nuclei are innervated by the corticobulbar tract

A

Trigeminal motor nucleus
Nucleus ambiguus
Facial motor nucleus (upper face)
Facial motor nucleus (lower face)
Hypoglossal nucleus

22
Q

what are the functions of:
Trigeminal motor nucleus
Nucleus ambiguus
Facial motor nucleus (upper face)
Facial motor nucleus (lower face)
Hypoglossal nucleus
responsible for

A

trigeminal: muscles of mastication
- Ambiguus: pharynx and larynx muscles
- 2 subnuclei for facial nucleus upper face and lower face
- Hypoglossal: tongue muscles

23
Q

what is the organization of the fibers of the corticobulbar tract
- how is this different than corticospinal

A
  • crossed and uncrossed fibers
  • completely crossed - cortico spinal
24
Q

how are the nerves of the lower face and tongue organized
- ex
- what does this resemble

A
  • theyre completely crossed
  • so left buccinators are controlled by the right motor cortex
    -similar to corticospinal r=tract
25
Q

what is bells palsy produced by

A
  • lesion to the facial nerve and facial nucleus
26
Q

what does a lession to the left facial nerve cause

A
  • paralysis to the left half of the face including the eye, mouth, and forehead
27
Q

what happens when you get a lesion to the cortex before it gets to the motor nucleus of 7 on the right side

A
  • the axons will degenerate and pt loses control of the lower part of the face of the left side
28
Q

what does it mean a pt has paralysis to the lower half of the face vs the whole half

A
  • lower half = stroke ( central weakness/lesion)
  • whole half = bells palsey (peripheral weaknes/lesion)
29
Q

how many neurons in the upper face vs lower face
- what happens if there is a stroke in the right side

A
  • upper face has 2 neurons ( one goes right the other goes left)
  • lower face has 1
  • lower left face droops but upper doesnt since the left neuron is still functional
30
Q

what are the 2 categories of pahthophysiology of the motor cortex

A

epilepsy
lesions

31
Q

jacksonian march

A
  • observed epileptic seisures
    and observed the pattern of spread of the convulsion
  • he came up with a somatatopic map of the motor cortex
  • he observed the convulsion would spread to different body parts ( this is the jacksonian march)
32
Q

what occurs in LMN lesions

A

Severee muscle atrophy
fasciculation ( rippling)
hyporeflexia
decreased/ flacid muscle tone

33
Q

what occurs in UMN lesions

A
  • slight muscle atrophy
  • no fasciculation
  • hyperreflexia
  • increased/spastic muscle tone
34
Q

why should their be spasticity in the UMN lesion

A

cerebral cortec acts on the reticuloformation in a inhibatory way.
- if inputs of the cerebral cortex are removed the reticuloformation is no longer inhibited causing spasticity

35
Q

spastic hemiplegia

A
  • paralysis of the lower half of the face
  • arm has excess tone ( flexion in the elbow,)
  • excess tone in the lower limb as well
36
Q

babinski response
- what is normal and abnormal

A
  • response that appears with a person with a stroke
  • if you stroke the the sole of the foot you get flaring of the foot ( midly interitating stimulus that induces withdrwal response)
  • normal would cause toes to curl
37
Q

how does the babinski respose affect babies? what does this mean?
what occurs if you have stroke

A
  • babies flare toes when you touch the foot but get surpessed as you begin to walk and become an adult. however if you have a stroke this resposne will reappear

neuro exam 3 (10 decks)

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