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Motor tracts Flashcards

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1
Q

upper motor neuron

A

arise and are contained within the cerebral cortex or brain stem

axons travel in desscending tracts and will synapse with LMN or interneurons of the spinal tract

Corticospinal tract, and the corticobulbar tract

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2
Q

Lower motor neurons

A

Directly innervate the skeletal muscle

Gamma motor neuron: medium sized myelinated, project to intrafusal fibers in muscle spindle

alpha motor neuron: large cell bodies and large myelinated axons, project to extrafusal skeletal muscle

Ex: Peripheral nerves and cranial nerves

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3
Q

Corticospinal tract pathway

A

Direct pathway ( from cerebral cortex to spinal cord and out to muscles)

Medial corticospinal tract: postrual muscles (not clinically significant 10 percent of fibers)

Lateral corticospinal tract: limb muscles and fractination
-90percent of fibers

Pathway:
-Cell bodies arise in the cortex
-Descends from the cortex through the posterior limb of the internal capsule
-Continues through the cerebral peduncles, anterior pons, Pyramids
-fibers deccusate in the pyramids in the lower medulla (decusation of the pyramid)
descends the lateral column of the spinal cord and will synapse on the LMN

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4
Q

Voluntary motor control

A

Primary Motor cortex (brodmanns area 4)

  • Precentral gyrus
  • initiates voluntary mvmt
  • other supplementary motor area and premotor cortex give input to the primary motor cortex as well

similar somatotopographic distribution to somatosensory: Feet medial, arms hand middle, face is lateral

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5
Q

How does the corticospinal tract ascend from the cortex and what is its blood supply in this structure

A

Posterior limb of the internal capsule

  • anterior=Arms
  • posterior= legs

blood supply: lenticulostriate arteries

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6
Q

What travels in the sublenticular limb of the internal capsule

A

Auditory radiation

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7
Q

What travels in the Retrolenticular limb of the internal capsule

A

Optic radiation

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8
Q

Where does the Corticospinal tract travel in the midbrain and whats its blood supply

A

Posterior Cerebral A (P1)

and in the middle 1/3 of the Cerebral peduncle

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9
Q

Where does the corticospinal tract travel in the pons and what is its blood supply

A

Found in the anterior pons with the pontine nucleus and fibers around it

Paramedian branch of the basilar artery

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10
Q

Where does the corticospinal tract travel in the medulla and what is its blood supply

A

found in the pyramid where it will decussate at the caudal medulla

Anterior spinal artery specifically the sulcal branch

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11
Q

Where does the corticospinal tract travel in the spinal cord and what is its blood supplyy

A

Posterolateral region in the lateral corticospinal trct

the Arms (medial portion of the tract) get blood supply by the anterior spinal artery

the legs (lateral portion of the tract) get blood supply by the posterior spinal A

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12
Q

Where does the UMN synapse in the spinal cord

A

on the ventral horn with the LMN

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13
Q

What travels in the medial Corticospinal tract

A

Controls postrual and proximal movements of the neck, shoulder and trunk muscles

has the same pathway as the corticalspinal tract until the medulla it does not cross and will travel in the medial corticospinal tract
(only 10 percent of the fibers travel this route)

blood supply will be the anterior spinal A

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14
Q

what is the somatotopographic organization all the way down the Corticospinal tract

A

cortex: legs medial and hand lateral

cerebral peduncle: legs anterior and lateral, hand posterior and medial

pons: legs lateral, hand medial
medulla: legs lateral, hand medial

spinal cord: legs lateral, hand medial

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15
Q

What is the Corticobulbar tract and what does it carry

A

also called corticonuclear

arises from ventral part of the cortical area 4

descends brain stem and influences muscels innervated by cranial nerves including motor nuclei:

Trigeminal
Facial
glossopharyngeal
vagus
spinal accessory
hypoglossal

axons will decussate and control muscles on contralateral side

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16
Q

Where does the corticobulbar tract travel in the internal capsule, and in the midbrain , pons, and medulla

A

the genu

just medial to the corticospinal tract in the cerebral peduncle

in the anterior pons

and in the pyramids

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17
Q

Location of the CN V, VII, IX, X, XII, XI in the brain stem

A

pons: V, VII
medulla: IX, X, XII

spinal cord: XI

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18
Q

What type of input: ipsilateral, contralateral, bilateral does each CN recieve: V, VII, IX, X, XI, XII

A

V: bilateral input

VII: bilateral forehead
contralateral lowerface

Muscles of the palate: contralateral

  • Uvula will deviate in lesion
  • ipsilateral to UMN damage
  • Contralateral LMN damage

Muscles of the tongue: Contralateral

  • tongue protruds in a lesion
  • contralateral to UMN damage
  • ipsilateral to LMN

Accessory: Ipsilateral

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19
Q

LMN topographically organization of the ventral horn

A

Medial LMN project to axial muscles
Lateral LMN project to limb muscles

LMN innervating the flexors are tend to be posterior
LMN innervating the extensors tend to be anterior

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20
Q

Indirect pathways: Medial UMN tracts

Study These Flashcards
A

Tectospinal tract
Medial reticulospinal tract
Lateral vestibulospinal tract
medial vestibulospinal tract

These go to activate antigravity axial muscles

21
Q

Indirect pathways: Lateral UMN tracts

Study These Flashcards
A

Rubrospinal tract
Lateral reticulospinal tract

To activate antigravity LMN of limb muscles

22
Q

Lateral vestibulospinal tract

Study These Flashcards
A

Vestibular nuclei to spinal cord

Ipsilateral LMN
Innervating postural muscles of Limb extensors against gravity

23
Q

Medial Vestibulospinal tract

Study These Flashcards
A

Vestibular nuclei to spinal cord

to cerviical and thoracic (neck and shoulder muscles)
coordination of head movements

24
Q

Medial (pontine) Reticulospinal tract

Study These Flashcards
A

Pontine reticular formation to spinal cord
ipsilateral

Ipsilateral LMN innervating postural extensors and postural reflexors

25
Lateral (medullary) reticulospinal tract
Medullary reticular formation to spinal cord ipsilateral Facilitates flexor motor neurons and inhbits extensor motor neurons (innhibit of spinal segmental reflexes)
26
Rubrospinal tract
Red nucleus to spinal cord contralateral innervates upper limb flexors
27
Tectospinal tract
superior colliculus to upper spinal cord contralateral to neck muscles to help with coordination of the head with eye movements
28
Corticospinal tract
Fine motor control of hand and limbs motor neuron recruitment to increase force inhibition of postural reflexes
29
Corticobulbar tract
control muscles of face, chewing, speech, nd swallowing
30
What happens if their is a LMN lesion
Flaccid paralysis Wasting or atrophy Hyporeflexia or areflexia due to denervation hypotonia - decreased muscle tone Denervation hypersensitivity - fasciculations
31
Upper motor neuron signs or lesion
direct: loss of distal extremity strength and dexterity babinski sign indirect: Hypertonia Spasticity: rate dependant resistance, with collapse of the resistance at the end of the range of motion: clasp knife phenomenon Rigidity: not rate or force dependant, constant throughout range of motion Hyperflexia: may see clonus Pronator drift
32
either UMN or LMN will tell you the exact level of the lesion?
LMN
33
If the UMN lesions at or above the lower medulla what side will the clinical signs be on
contralateral
34
if the UMN lesions at the level of the spinal cord what side will the clinical signs be on
ipsilateral
35
What is affected when a paitent presents with decorticate posture
lesion above the level of the red nucleus, usually includes the midbrain thumb tuucked under flexed fingers in a fist position, pronation of forearm, flexion at elbow with lower extremity extension with foot inversion
36
what is affected when a paitent presents with decerebrate posture
Lesion below red nucleus but above reticulospinal and vestibulospinal nuclei upper extremity in pronation and extension and the lower extremity in extension
37
spinal shock mirrors what type of lesion characteristics
LMN lesions
38
hemisection of the spinal cord
Also called Brown-sequard syndrome pain and temp from contralateral side of body loss 2 segments below the lesion Discriminative touch and proprioception on ipsilateral LMN signs at level of lesion: flacid paralysis UMN signs on ipsilateral side of lesion
39
Syringomyelia
Formation of a cyst within the spinal cord Pain and temp affected first -Anterior white commissure resulting in cape like deficit area Motor loss: - May have LMN signs if Ventral horns are affected - May have UMN signs if lateral corticospinal tract is affected Highly correlated with Chiari I
40
Anterior cord syndrome
Compression or damage to anterior part of spinal cord -usually due to spinal cord infarction, intervertebral disc herniation and radiation myelopathy - also can have damage to anterior spinal A - Lose bilateral Corticospinal tract, ALS and Anterior fasciculus
41
Central cord syndrome
Compression and damage of central spinal cord caused by usually cervical hyperextension symptoms similar to syringomyelia
42
Medial medullary syndrome
usually an issue with the Anterior spinal Artery Pyramid is affected= contralateral UMN damage Medial Lemniscus= contralateral vibration, proprioception, and Discriminative touch is loss Hypoglossal nucleus = LMN problems so the tongue will potray towards the lesion Dejerine syndrome
43
Lateral Medullary syndrome
usually arise with loss of Posterior Inferior Cerebellar Artery Wallenberg syndrome ALS = Contralateral Pain and temp to the body Spinal trigeminal nucleus = ipsilateral Pain and temp to the face Nucleus ambiguus= ipsilateral hoarseness and swallowing issue, uvula deviate away from lesion Vestibular nuclei = dizziness and nausea Restiform body = ataxia and wide base gate Hypothalamicspinal tract = ipsilateral horners syndrome
44
Central Seven Palsy
lesion to the corticobulbar tract involving the CN VII muscles of the upper face are controlled by bilateral so no deficits there muscles of the lower face are controlled contralateral so there will be drooping of muscles at the corner of the mouth on the contralateral side of the lesion
45
Bells palsy
LMN damage causing ipsilateral flaccid paralysis of upper and lower face
46
Weber syndrome
supplied by the Posterior Cerebral Artery P1 in the midbrain Corticospinal tract = contralateral UMN problems Corticobulbar tract = Contralateral facial drop Oculomotor N = dilated pupil and eye looks down and out
47
Spastic Cerebral palsy
Movement dysfunction : - abnormal sypraspinal influences - failure of normal neuronal selection - consequent aberrant muscle development Motor disorders: - Paresis - Abnormal tonic stretch reflexes, both at rest and during movement - Reflex irradiation - lack of postural preperation prior to movement - abnormal cocontraction of muscles
48
Amyotrophic Lateral Sclerosis (ALS)
Lou Gherigs disease Destroys only the somatic motor neurons: -UMN and brainstem and spinal cord LMN Leads to Paresis, myoplastic hyperstiffness, hyperreflexia, babinskis sign, atrophy, fasciculations and fibrillations Cranial nerve involvement leads to difficulty breathing swallowing and speaking
49
Polyneuropathy
involvement of sensory motor and autonomic progressing from distal to proximal due to dying back or impaired axonal transport demyelinization may also contribute glove and stocking

Neuro Endocrine 2 (24 decks)

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