L4 Motor learning and neurological syndromes Flashcards Preview

Theme 2: Sensory Inputs and Motor Outputs > L4 Motor learning and neurological syndromes > Flashcards

Flashcards in L4 Motor learning and neurological syndromes Deck (22)
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1
Q

Hierarchy of motor control

A

High: strategy
-Association areas of neocortex and basal ganglia

Middle: Tactic
Motor cortex, cerebellum

Low: Execution
-Brainstem and spinal cord

2
Q

Corticospinal tracts

  • Function
  • Origin
  • site of crossover
A
  • PATHWAY: primary motor cortex>internal capsule>cerebral peduncle>pons> pyramid of medulla>Ant/Lat c.s tract
  • Lateral tract: 80-90% decussate at pyramids (hands and fingers)
  • Anterior tract: 10-20% decussate ipsilaterally at specific level of spinal motor neurons (muscles of upper leg and trunk)
  • Destruction: loss of muscle strength, reduced manual dexterity
  • Brodmanns Area 4 (and 6)
3
Q

Reticulospinal tract

A

Ventromedial descending motor pathway

  • Facilitates extension of limbs (upper arm)
  • locomotion and postural control

Path:

  1. Originates in reticular formation of brainstem
  2. Descends down spinal cord to form medial [pontine] and lateral [medullary] tract

facilitate voluntary movement-medial tract
inhibit voluntary movement- lateral tract

4
Q

Tectospinal tract

A

Ventromedial descending motor pathway

  • controls muscles of the neck, upper trunk and shoulders
  • coordinates head and eye movements

Path:

  • Originates in superior colliculus in tectum
  • Recieves visual information from retina and cortex

-Fibres cross in midbrain and travel down anterior white column of spinal cord- contralateral control

5
Q

Rubrospinal tract

A

Lateral descending motor pathway

Activates flexor muscles in arms

PATH:

  • origin-red nucleus
  • crosses at midbrain
6
Q

Vestibulospinal tract

A

Ventromedial descending pathway
Path:
-originates in vestibular nuclei of medulla [medial and lateral]
-sensory information originates from vestibular labyrinth in ear
-no crossing-remains ipsilateral

Medial tract
-controls head and neck movements

Lateral tract

  • activates extensor muscles in arms and legs
  • maintains upright and balanced posture
7
Q

Tectospinal and medial vestibulospinal

A

Control head and neck movements.

8
Q

Lateral vestibulospinal and reticulospinal

A

Activate extensor muscles in arms and legs.

9
Q

Decorticate posturing

A

Due to lesion above the red nucleus
- Rubrospinal tract intact and more active as regulation from cortex is disrupted [disinhibition] therefore facilitate flexors in the UL

10
Q

Decerebrate posturing

A

Causes extension in all limbs.

Mechanism:

  • Lesion below the red nucleus, rubrospinal tract is inhibited due to disruption
  • Upper limbs are extended due to activation of lateral vestibulospinal and reticulospinal tract
11
Q

Stroke and posture

A

Stroke in middle cerebral artery can affect motor cortex and corticospinal tarct

  • upper limb flexion
  • lower limb extension

Other features

  • Increased tone (spasticity),
  • Brisk Reflexes (overactive reflex due to UMN lesion
  • Babinski reflex
  • Clonus(involuntary rhythmic contractions)
12
Q

Corticobulbar pathway

A

FACE

involuntary 
decussate in pons
movements of face, neck, tongue, eye
 -facilitates mastication 
-vocal cords/swallowing
13
Q

Lower Motor Neuron lesion

A

Bell’s palsy

  • Damage to CN7 motor nucleus beyond stylomastoid foramen (ipsilateral facial muscle paralysis)
  • Facial asymmetry; Atrophy of facial muscles; Drooping of the mouth corner;
  • Cannot taste in ant 2/3; Cannot close eye or stop welling up; Eyebrow droop;
  • Lips cannot be held tightly together;; sound hypersensitivity;
  • Flaccid paralysis of muscles; decrease superficial reflexes and tone; muscle atrophy; fasciculations
14
Q

Upper Motor Neuron lesion

A
  • Damage to neuronal cell bodies in cortex or their axons
  • No voluntary control of contralateral lower facial muscles (voluntary control of forehead remains)
  • Spasticity: exaggerated reflexes; hyperreflexia; clonus: jerky contractions following sudden muscle stretching; weakness; increase tone; Babinski’s sign; loss of voluntary movement
15
Q

Parasagittal Meningioma

A

commonly neoplasm of the meninges
can press on specific areas of the motor cortex controlling legs
bilateral leg weakness and spasticity

16
Q

Which tracts activate extensor muscles?

A

lateral vestibulospinal and reticulospinal tracts

17
Q

Brisk Reflex

A

Spasticity: increased tone to rapid passive muscle stretching
Spinal inhibitory interneurons altered

18
Q

Facial Palsy (Bell’s palsy)

A

Damage to CN7 motor nucleus beyond stylomastoid foramen (ipsilateral facial muscle paralysis)

Top half of face is innervated bilaterally
-Damage in one CN7 can still give sensation to top half of face

Lower half of the face is contralaterally innervated
-Lesion causes loss of control on lower face

Lesion in UMN affects the entire half of the face

19
Q

Apraxia

A

Inability to carryout purposeful movements in the absence of paralysis or paresis.

20
Q

Name 3 descending ventromedial pathways

A
  • reticulospinal
  • tectospinal
  • vestibulospinal

Maintain body and posture

21
Q

Which tracts activates extensor muscles?

A

lateral vestibulospinal

reticulospinal

22
Q

anterior cingulate gyrus

A

connections to both the “emotional” limbic system and the “cognitive” prefrontal cortex.

“smiling”