UMNs Flashcards
Cell bodies are located where?
Motor Cortex
OR
Brainstem
UMNs that arise from Brainstem project to…
Medial ventral horn
UMNs that arise from Motor Cortex project to
Lateral ventral horn
Which pathways go Brainstem –> Medial horn (3)
Vestibulospinal
Reticulospinal
Colliculospinal
Which pathway goes Cortex –> Lateral horn
Lateral Corticospinal
Which pathway goes Brainstem –> Lateral horn
Rubrospinal
Vestibulospinal Tract function
Balance & posture
Medial Vestibulospinal Pathway
- Semi Canals & Otolith –> Vestibular Nuclei (CN 8).
2. Vestibular –> Medial cord (BILATERAL)
Reticulospinal Tract function
Balance & posture
Reticulospinal Pathway
Reticular Formation (pons + medulla) –> Medial cord
Difference between Vestibulospinal & Reticulospinal
Vestibulo uses FeedBack - responds to postural changes.
Reticulo uses FeedForward - postural adjustments to stabilize before/during movement.
Colliculospinal Tract function
Head/neck movement
Colliculospinal Pathway
- Optic tracts –> Superior Colliculus (midbrain)
2. Superior Colliculus –> Medial C-spinal cord
Rubrospinal Tract function
Arm/shoulder movement
Rubrospinal Pathway
- Red Nucleus (midbrain) –> intermediate & lateral C-spinal cord
Motor Cortex receives input from (3)
Basal Ganglia
Cerebellum
Sensory
Corticospinal projects from Cortex –>
Spinal Cord
Corticobulbar projects from Cortex –>
Brainstem
Primary Motor Cortex fires when?
During movement
Premotor Cortex fires when?
Before movement
Lateral Premotor Cortex (PMA) invx which muscles? Selects movements based on what?
Proximal
Based on external events
Medial Premotor Cortex (SMA) invx which muscles? Selects movements based on what?
Distal
Based on internal cues
Corticospinal Tract function
Trunk/extremity movement
Lateral Corticospinal Pathway
- Axons –> Internal Capsule –> Cerebral Peduncles –> Pons –> Medulla.
- Cross in Caudal Medualla.
- Synapse on alpha-Motor N in lateral ventral horn.
Ventral Corticospinal Pathway
- Axons –> Internal Capsule –> Cerebral Peduncles –> Pons –> Medulla.
- Some do not cross.
- Synapse on axial muscle N pools.
- Some send collaterals that cross over for bilateral trunk motion.
Corticobulbar Tract function
Head/neck movement
Corticobulbar Pathway
- Axons synapse on CN Motor Nuclei
Some CN receive bilateral, others receive from contralateral Cortex
Upper Facial Motor Nucleus: receives bilateral or contralateral invx?
Bilateral
Lower Facial Motor Nucleus: receives bilateral or contralateral invx?
Contralateral
Facial Paralysis symptoms
Lower muscles on contralateral side - weak/paralyzed.
Upper muscles on both sides - intact.
UMN Syndrome Phase 1
Acute/Spinal Shock
Flaccidy & hypotonia on contralateral side.
Muscle activity & reflexes temporarily lost.
UMN Syndrome Phase 2
Consistent Pattern After several days, circuits regain function. Babinski & Clonus. Hypertonia & Hyperreflexia. Loss of fine motor movement.