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Neuroendocrine Exam 2 > Motor Tracts > Flashcards

Motor Tracts Flashcards

1
Q

Apraxia

A

-inability to perform learned movements on command

recognize position of limb but cannot perform correct motor sequence

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2
Q

Agnosia

A
  • loss of the ability to recognize objects, faces, voices, or places
  • right-left disorientation
  • can still do things with dominant hand (autonomic-voluntary dissociation)
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3
Q

Encephalization

A

dominant influence of primary motor cortex on subcortical systems

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4
Q

Primary Motor Cortex

A
  • corticospinal fibers
  • precise movements of digits/distal extremities
  • pre-central gyrus
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5
Q

Pre-Motor Cortex

A
  • anterior to precentral gyrus
  • Broca’s Area
  • ideation and programming of movement patterns
  • receives input from cerebellum via ventral anterior nucleus of thalamus
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6
Q

Upper Motor Neurons

A
  • arise from cerebral cortex or brainstem
  • axons travel in descending tracts
  • synapse with lower motor neurons or interneurons of spinal cord
    ex. Corticospinal tract and corticobulbar tract
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7
Q

Lower Motor Neurons

A

-directly innervate skeletal muscles
-cell body in spinal cord or brainstem and synapses on skeletal muscle fibers
classified as:
1. Gamma motor neuron - medium sized, myelinated, project to intrafusal fibers in muscle spindle
2. alpha motor neuron - large cell bodies and large myelinated axons project to extrafusal muscle fiber

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8
Q

Lesions of Lower Motor Neurons

A

affects nerve fibers traveling from the anterior horn of the spinal cord to the associated muscle

  • flaccid paralysis: limp muscle with no resistance to passive movement
  • areflexia: loss of efferent component of reflex arc/no muscle reflex
  • atonia: absence of muscle tone due to destruction of gamma motor neurons
  • atrophy: denervated muscle atrophies due to loss of stimulation from motor neurons
  • fasciculations: twitchings of denervated muscle due to hypersensitivity of motor end plate
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9
Q

Lesions of Corticospinal Tract

A

unilateral lesions = contralateral spastic hemiplegia or hemiparesis

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10
Q

Lesions of Lateral Corticospinal Tract

A

unilateral lesions = ipsilateral paralysis or paresis of distal limb musculature innervated by the spinal segments below level of lesion

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11
Q

Lesions of Upper Motor Neurons

A

lesion of the neural pathway above the anterior horn of the spinal cord or motor nuclei of the cranial nerves

  • spastic paralysis of axial and proximal limb muscles and some spastic paralysis of distal limb muscles esp in UE
  • hypertonia
  • hyperreflexia
  • Babinski sign
  • clonus
  • rigidity
  • disuse atrophy
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12
Q

Corticospinal Tract

A
  • arise from pyramidal Betz cells in primary motor and pre motor cortices = UMNs
  • UMNs arise in cortex and synapse on LMNs in spinal cord
  • CST descends through corona radiata > internal capsule > cerebral peduncles > pons > upper medulla
  • decussation of most fibers in lower medulla = lateral CST
  • continuation of remainder of fibers that don’t cross = anterior CST
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13
Q

Occlusion of the Lenticulostriate Arteries

A
  • lenticulostriate arteries of the MCA supply internal capsule
  • weakness of face, arm, leg
  • hyperreflexia
  • Babinski sign
  • Clonus
  • Spasticity
  • contralateral weakness and sensory loss
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14
Q

Central Seven Palsy/Central Facial Paralysis

A
  • lesion of corticobulbar tract involving CN VII
  • muscles of upper face are controlled by equal number of fibers from both hemispheres
  • muscles of lower face controlled by contralateral hemisphere
  • lesion rostral to facial motor nucleus results in drooping of muscles at corner of mouth on OPPOSITE side of lesion
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15
Q

Bell’s Palsy

A

ipsilateral flaccid paralysis of upper and lower face

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16
Q

Corticobulbar Tract Function

A

controls muscles of face, chewing, speech, swallowing

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17
Q

Corticobulbar Tract Blood Supply

A

lentriculostriate arteries of MCA and anterior choroidal arteries

18
Q

Corticispinal Tract Function

A

fine motor control of hand, motor neuron recruitment to increase force, inhibition of postural reflexes

19
Q

Corticospinal Tract Blood Supply

A

anterior and posterior spinal arteries, vertebral arteries, paramedian branches of caudal portions of basilar artery

20
Q

Corticobulbar Tract

A
  • arises in premotor and primary motor cortex
  • descends into brainstem and influences muscles innervated by cranial nerves V, VII, IX, X, XI, XII including motor nuclei
  • axons will cross and control muscles on contralateral side
  • when descending will travel through genu of internal capsule
  • continues passing through cerebral peduncles, anterior pons, and pyramids
  • stops at specific motor nucleus
21
Q

Oculomotor N Motor Components

A
  • medial rectus
  • superior rectus
  • inferior rectus
  • inferior oblique
  • levataor palpebrae superioris
22
Q

Trochlear N Motor Components

A

superior oblique

23
Q

Trigeminal N Motor Components

A
  • muscles mastication
  • mylohyoid
  • ant belly digastric
  • tensor tympani
  • tensor veli palatini
24
Q

Abducens N Motor Components

A

lateral rectus

25
Q

Facial N Motor Components

A
  • muscles of facial expression
  • posterior belly of digastric
  • stapedius
26
Q

Glossopharyngeal N Motor Components

A

stylopharyngeal muscle

27
Q

Vagus N Motor Components

A

pharyngeal muscles

laryngeal muscles

28
Q

Spinal Accessory N Components

A

trapezius and SCM

29
Q

Hypoglossal N Components

A

intrinsic and extrinsic muscles of tongue

30
Q

Amytrophic Lateral Sclerosis

A
  • LMN deficits: anterior horn cells, hypoglossal nucleus, nucleus ambiguus, facial motor nucleus
  • UMN deficits: chronic progressive degeneration of corticospinal tracts
  • ALS causes LMN paresis and atrophy of upper extremity muscles
  • dysarthria, dysphagia, tongue paresis
  • involvement of CST causes spastic paralysis, hyperreflexia, Babinski sign
  • no sensory deficits of ALS but there can be sensory deficits from other diseases
  • death happens bc of bulbar paralysis (resp centers)
31
Q

Decorticate Posturing

A
  • UMN lesion
  • regidity
  • lesion above red nucleus above midbrain
  • thumb tucked under flexed finers in fisted positoon
  • pronated forearm
  • flexion at elbow
  • LE in extension with foot inverted
32
Q

Decerebrate Posturing

A
  • UMN lesion
  • lesion below red nucleus but above reticulospinal and vestibulospinal nuclei
  • UE pronation and extension
  • LE extension
33
Q

Complete Spinal Transection

A
  • all sensation lost 1 or 2 levels below lesion
  • hyperactive reflexes, clonus
  • Babinski
  • spasticity
  • LMN signs at level of lesion
34
Q

Syringomyelia

A
  • most often at C4/5
  • associated with Chiaris Type 1
  • formation of cyst within SC
  • pain and temp first affected (ant white commissure, resulting pattern is caped shaped)
  • motor loss (LMN signs if ventral horns affected; UMN signs if lateral corticospinal tract affected)
35
Q

Frontal Lobe

A

attention in motion

36
Q

Pre-Frontal Lobe

A

motivation and memory in motion

37
Q

Ideomotor Apraxia

A

inability to correctly mimic hand gestures due to lesions in left parietal lobe and premotor cortex

38
Q

Pyramidal System

A

corticospinal and corticobulbar tracts

39
Q

Lenticulostriate Infarct

A
  • ischemia within areas supplied by branches of Middle cerebral artery or internal carotid artery
  • secondary to cardiac embolisms
  • clinical signs: motor/sensory deficits and cognitive dysfunction
40
Q

Spasticity

A
  • caused by lesions in the pyramidal tract (UMN of CST)
  • weakness present
  • more resistance in one direction vs other
  • velocity dependent (more noticeable with fast motions)
41
Q

Rigidity

A
  • Seen in extrapyramidal lesions (i.e. Parkinson’s) such as the rubrospinal or vestibulospinal tracts
  • Same resistance in all directions
  • Not velocity dependent – does not vary with speed of movement of muscle groups involved

Neuroendocrine Exam 2 (11 decks)

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