Lecture 12: Motor Tracts Flashcards
How many neurons are involved in motor tracts?
2: Upper Motor Neurons (UMN) and Lower Motor Neurons (LMN)
Where do UMN come from?
Cerebral Cortex or Brainstem
Where do LMN come from?
Cell body in spinal cord or brainstem that directly innervates skeletal muscle
What are examples of LMN?
Peripheral and motor component of Cranial Nerves
What is the direct somatic motor pathway?
Cerebral Cortex –> brainstem/spinal cord –> muscle
What is the indirect somatic motor pathway?
Direct pathway + synapses in brainstem, basal ganglia, thalamus, reticular formation, and cerebellum
Briefly, how does the corticospinal tract work?
UMN from cortex synapses at LMN at spinal cord, which allows voluntary movement
What does the medial and lateral corticospinal tract do?
Medial: Postural muscles (not imp)
Lateral: Voluntary movement
In the corticospinal tract, how do UMN reach LMN?
- Leave motor cortex via posterior limb of internal capsule
- Descend to middle ⅓ of cerebral peduncle
- Travel down anterior pons and medulla
- Decussate in pyramids of medulla
- Synapse at LMN in spinal cord
What initiates voluntary movement?
Mostly the Primary motor cortex in precentral gyrus
*controls opposite side of the body
What supplies the cerebral peduncle?
P1 of Posterior Cerebral Artery
What supplies anterior pons?
Paramedian Branches of Basilar Artery
What supplies pyramid?
Sulcal Branches of Anterior Spinal Artery
