Corticospinal Tract Flashcards
Three types of movements performed by Corticospinal Tract
Reflexes
automatic postural adjustments
Voluntary (goal directed, internally generated, get better with practice)
The Corticospinal tract has an UMN that projects to:
Lower motor neurons in the ventral horn of ALL levels of the spinal cord
The Corticospinal tract UMN projects to LMN in the _____ horn in which sp cord levels
Ventral horn
all levels
What is the function of the UMN–> LMN in the corticospinal tract
Voluntary movement of DISTAL extremeties
When does the corticospinal tract decussate to the other side?
At the medulla/sp cd junction
Which three descending motor pathways project to sp cd
Cortical structures (primary motor cortex, prefrontal motor and somatosensory and parietal) Subcortical strucutes (basal ganglia, cerebellum, thalamus) Brainstem
The UMN for the corticospinal tract begins in:
Cerebral cortex… primary motor cortex
What is the approximate location of cortical lesion in pt who has facial weakness?
within the longitudinal fissure of the lateral cortical surface
Blood supply for the lateral part of the cortex (face)
the MCA
What is the blood supply for the lower limbs?
ACA
The motor map of the cortex overlaps and exhibits plasticity meaning….
it can change with increased use or disuse of a body part (PRACTICE… you can recover use of limbs from stroke!)
Primary motor neurons connect to __________ that innervate a skeletal muscle via corticospinal tract
alpha motor neurons
The corticospinal tract will ________ flexors and __________ extensors
excite flexors
inhibit extensors
Four areas of cortex CST arise from
- Primary motor cortex
- Betz of lamina V (precnetral gyrus)
- Premotor cortex/Supplementary Cortex
- Pariatal lobe
Order the CST pass through from cortex
cortex–> corona radiata–> posterior limb of internal capsule–> middle of cerebral peduncle–> medullary pyraminds
CST go from Cortex –> _______–> posterior limb of internal caplse –> _________—> medullary pyramids
corona radiata
middle of cerebral peduncle
90% of the tracts will _______ at the cervicomedullary level and travel down the _______
decussate
Lateral corticospinal tract
The fibers that descend in the lateral corticospinal tract will descend in
lateral fasciculus to all cord levels
10% of the fibers will _______ at the cervicomedullary level and travel down the _______
stay ipsilateral
Anterior or Ventral corticospinal tract
Fibers that travel down the Anterior or ventral corticospinal tract decussate:
in the ventral white commisure to thoracic sp cd.
Lesions above the decussation result in _____ weakness
CONTRA
Lesions below the decussation result in______weakness
IPSI
The lateral wall of the third ventricle is the
thalamus
What lies between the caudate and putamen then alongside the thalamus
Internal capsule
which stroke would have more diffuse effects, corona radiata or the internal capsule
Internal capsule
Where in the midbrain does the CST pass through
the middle cerebral peduncle
What is the somatotopy of the spinal cord motor system?
All motor in the Ventral part of horn: trunk muscles more medial… extending out most lateral as digits and fine motor control
What is the major pathway for voluntary movement?
Corticospinal tract
As the Cerebral Crus goes into the Pons, what Neve is it close to?
Oculomotor Nerve III
What nerve sits right on top of the Medullary Pyramid?
Hypoglossal Nerve
What nerve lies in the Ponto/medully junction (close to start of pyramid)
Abducent Nerve
After the Pyramidal decussation, the Lateral Corticospinal tract will
stay lateral!, and ventral stays ventral
Weber Syndrome in the midbrain affects CN
III (oculomotor, vision)
Key CN in the pons
VI (abducens) abducting the eye
Medial medullary syndome in the medulla would affect CN
XII
A lesion in the Posterior Limb of the internal capsule would result in
Contralateral hemiplegia
A lesion in the cerebral peduncle or the Crus cerebri could rsult in which syndrome?
Weber Syndrome
Symtpoms of Weber syndrome
Contralateral paralysis of lower face/tongue/arm/leg and Ipsilateral oculomotor palsy (eye deviates laterally, ptosis, pupil is dialatead and fixed)
Weber syndrome could result from
Lesion in cerebral peduncle, Occulsion of PCA
What is the result of a CN III injury and what would cause it?
Ipsilateral oculomotor palsy:
eye deviates laterally, ptosis, pupil is dialated and fixed
A corticospinal tract lesion in the Cerebral peduncle would result in:
contralateral paralysis of lower face, tongue, arms and leg
A Lesion in the medullary pyramid is called
Medial Medullary syndrome
What is a possible cause of medial medullary syndrome?
Occulsion of Verterbral artery or anterior spinal artery
What three lesions result because of Medial medullary syndrome
Corticospinal tract lesion
CNXII lesion
Medial Lemniscus injury
Symptoms of Medial Medullary Syndrome
Corticospinal tract lesion: contralateral hemiparasis of arm, leg (FACE SPARED)
CNXII injury: Ipsilateral paralysis of tongue (lick wound)
Medial Lemniscus injury: Contralateral loss of touch, vibration, joint position, sensation for half of body
What happens to the Medial Lemniscus in a medial medullay syndrome ( occusion of vertebral or anterior spinal artery)
Medial Lemniscus injury: Contralateral loss of touch, vibration, joint position, sensation for half of body
What happens to the CNXII in a medial medullay syndrome ( occusion of vertebral or anterior spinal artery)
Ipsilateral paralysis of tongue
What happens to the Corticospinal Tract in a medial medullay syndrome ( occusion of vertebral or anterior spinal artery)
Corticospinal tract lesion: contralateral hemiparasis of arm, leg (FACE SPARED)
Occusion of the vertebral artery or anterior spinal artery could lead to
Medial Medullary Syndrome
See signs of ipsilateral spastic paralysis and an ipsilateral Babinski Sign could be
a lesion in the spinal cord on the SAME side
