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neuromuscular pt 1 > Motor Tracts > Flashcards

Motor Tracts Flashcards

1
Q

What are motor Tracts?

A
  • Descending tracts
  • start in CNS/made of UMNs
  • Project from cortical and brain stem centers to LMN’s (alpha and gamma) and to interneurons in the spinal cord and brain
  • different descending motor tracts control different types of movements, depending on where they synpse
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2
Q

General Classification of Motor Tracts

A
  • Fine volitional motor control
  • automatic postural control
  • Background control
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3
Q

General Classification of Motor Tracts

Fine volitional motor control motor tracts

A
  • located laterally in the spinal cord
  • control distal muscles usually flexors
  • lateral - fractioned movements, face and neck
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4
Q

General Classification of Motor Tracts

Automatic postural control tracts

General

A
  • located medially in the spinal cord
  • control postural muscles, usually extensors
  • medial UMNs = postural and girdle
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5
Q

General Classification of Motor Tracts

Background Control

A
  • located throughout the ventral horn
  • background levels of excitation in the cord and facilitate local reflex arcs
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6
Q

Unilateral tract

A
  • influences LMNs on ONE side of the body
  • either ipsliateral or contralateral to the origin of the tracts fibers
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7
Q

Bilateral tract

A
  • excites LMNs bilterally from each side of the tracts origin
  • some fibers cross and some stay ipsilaterally
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8
Q

Hemiparesis vs hemiplegia

A
  • Hemiparesis = 1 side is weak
  • Hemiplegia = 1 side is paralysed
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9
Q

What are the lateral descending tracts

A
  • Lateral corticalspinal tract (LCST)
  • cortiobrainstem tract
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10
Q

Lateral corticospinal tract

A
  • important for fractionation of movement of the limbs (selective motor control/activating specific muscles)
  • most important pathway controlling voluntary movement
  • activates inhibitory interneurons to prevent unwanted muscles from contracting
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11
Q

Lateral corticospinal tract pathway

A
  • starts in motor areas of cortex such as: primary motor cortex, premotor cortex, supplementary motor area (all have somatotopic representation)
  • through internal capsule
  • through the cerebral peduncles in the midbrain through ventral pons
  • through the pyramids in the medulla (crosses) and then through the lateral column of the spinal cord to the ventral horn of the spinal cord
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12
Q

Functions of

  1. primary motor cortex
  2. premotor area
  3. supplementary motor area
A

Primary Motor Cortex - Voluntarily controlled movements

Premotor area - Control of trunk and girdle muscles, anticipatory postural adjustments

Supplementary motor area - Initiation of movement, orientation planning

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13
Q

Where does the LCST decussate and what does it control

A
  • the first axon crosses in the medulla
  • left motor cortex controls right-sided voluntary movement and vice-versa
  • 10% of fibers do stay on the same side
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14
Q

What would happen with a lesion to the LCST above the pyramids

A
  • symptoms contralateral to the lesion side
  • body and face affected with some cranial nerve involvement
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15
Q

What would happen with a lesion to the LCST below the pyramids

A

same side of the body is affected

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16
Q

LCST synapes

A
  • none in the brain
  • first synpase is in the spinal cord
  • the motor neurons then travel to their target structure (muscles)
17
Q

What are some pyramidal/LCST lesion signs

A
  • pyramidal flaccid paralysis
  • hypertonia and spastic paralysis
  • babinski

pyramidal signs = UMN signs

18
Q

Corticobrainstem tract

pathway

A
  • Originates in the motor cortex (where face, tongue, throat and largest muscles the move the head are represented)
  • initially travels with lateral corticospinal tract
  • ends in differnt regions of the brainstem on cranial nerve nuclei
19
Q

Function of the corticobrainstem tract

A
  • provides input to muscles of the face, tongue, pharynx, larynx, trapezius and SCM muscles
  • most cranial nerve nuclei receive bilateral input (CN VII is the exception)
  • CN I, II are in CNS and are not receiveing input from here
  • Projection usually:
    Bilateral (therefore, upper facial mm’s often spared with CVA)
  • Exception – CN VII: Projection to lower face muscle mns Contralateral

LMN to mm’s of lower face are controlled by contralateral corticobrainstem fibers; LMN’s to muscles of the upper face are bilaterally controlled by corticobrainstem fibers

20
Q

Corticobrainstem tract pathway

A
  • originates in motor coretx
  • initially travels with LCST
  • ends in different regions of brainstem on cranial nerve nuclei
21
Q

Differentatie between bells palsy and a CVA

A
  • UMN lesion with a stoke will lose voluntary control of lower muscles of fascial expression due to the unilateral expression
  • forehead muscles will be spared due to bilateral innervation
  • with Bells palsy CN 7 is affected (LMN) and therefore affects both upper and lower parts of the face
22
Q

Medial descending tracts

A
  • Medial corticospinal tract
  • reticulospinal tract
  • medial vestibulospinal tract
  • lateral vestibulospinal tract
23
Q

Describe how medial and lateral tracts generally travel in the spinal cord

A
  • Medial UMNs descend in the anterior column of the spinal cord and synapse with LMNs and interneurons located in the anteromedial gray matter
  • Lateral corticospinal tract descends in the lateral column of the spinal cord and synapses with LMNs located in the anterolateral gray matter
24
Q

Medial corticospinal tract

function

A
  • innervates muscles of trunk, neck, shoulder
25
Q

Desribe the pathway for the medial corticospinal tract

A
  • first axon travels from the cortex
  • through internal capsule
  • through cerebral peduncles in midbrain
  • through ventral pons
  • through medulla
  • descends medially in spinal cord
  • to ventral horn of spinal cord (cervical and thoracic only)
  • some fibers cross in the spinal cord/Some will stay
26
Q

Reticulospinal tract

what it is important for

A
  • important in postural control and gross limb movemetns
  • coordinates gait
  • involved in reaching for objects
  • postural control
  • neck reflexs
  • anticipatory postural control
27
Q

What does the reticulospinal tract get input from

A
  • cerebral cortex
  • cerebellum
  • sensory information from the body
28
Q

Pathway of the reticulospinal tract

A
  • starts in the reticular formation of the PONS and medulla
  • through medulla
  • through anterior column of spinal cord
  • ventral horn of the spinal cord
  • descends bilaterally synapses on LMN
  • goes cervical, thoracic and lumbar
29
Q

Flexion synergy

abnormal

A
  • one arm is unale to combine shoulder flexion with elbow extension during reaching
  • action of reticulospinal tracts unopposed by corticospinal tracts
30
Q

Medial vestibulospinal tract pathway

also what do the LMN in this pathyway faciliate

A
  • starts in medial vestibular nuclei in medulla and pons
  • descends bilaterally from upper medulla
  • to anterior column of the spinal cord
  • to lower motor neurons in cervical and thoracic spinal cord (ventral horn)
  • lower motor neurons facilitate back and neck muscles
  • information about head movement and position
31
Q

Lateral vestibulospinal tract

pathwayand what LMNs will faciliate

A
  • starts in lateral vestibular nucleus of pons and medulla
  • travels ipsilaterally to anterior column of the spinal cord
  • to ventral horn of spinal cord
  • goes cervical, thoracic, lumbar
  • LMNs facilitate extensors and inhibit flexors important to keep use upright
32
Q

Non-specific motor tracts

A

Ceruleospinal tract
raphespinal tract

33
Q

ceruleospinal tract

A
  • starts in locus ceruleus of brain stem
  • release NE
  • facilitates spinal motor neurons
34
Q

raphespinal tract

A
  • starts in raphe nucleus of brainstem
  • releases serotonin
  • helps modulate activity of spinal motor neurons

neuromuscular pt 1 (32 decks)

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