MEDICININE LEVEL 1 NEUROANATOMY AND PHYSIOLOGY: MOTOR SYSTEM

2. PYRAMIDAL TRACT EXTRAPYRAMIDAL TRACT
CONNECTION Monosynaptic and controls
small group of muscles
Polysynaptic and controls large
group of muscles
Corticobulbar tract
Corticospinal tract
Reticulo-spinal tract
Rubrospinal tract
Olivo-spinal tract
Vestibulospinal tract
ORIGIN CC (80% @precentral gyrus) to
spinal cord
Brainstem nuclei
FUNCTION Lateral: Fine movement
Ventral: Postural movement
Control body posture
Involuntary/ autonomic
movement

4.  UNILATERAL PYRAMIDAL TRACT LESION (R)
= CONTRALATERAL (L) PARALYSIS

5.  Fibers of pyramidal tract that synapse w/
CNs’nuclei (III, IV, V, VI, VII, IX, X, XI, XII)
@ BRAINSTEM
 Movements of eyes, tongue, swallowing,
expression, and speech

6.  Bilateral innervation – L and R Cranial nuclei are innervated from both c.hemisphere
 UNILATERAL LESION = (-) PARALYSIS bc BILATERAL INNERVATION (although
not strong anymore)
EXCEPT CN XII (tongue protrusion) and VII (lower face m.)
– receive (1) CONTRALATERAL innervation
 UNILATERAL UPPER MOTOR NEURON LESION = CONTRALATERAL face droop/
tongue protrusion, other parts functioning w/ (-) paralysis
 e.g left colticobulbar tract lesion  R side face droop/ R side tongue protrusion

8. UPPER MOTOR NEURON LOWER MOTOR NEURON
• Type of 1st order neuron
• Unable to leave the CNS
• Pyramidal tract – most
direct UMN tract
• Extrapyramidal
• Type of 2nd order neuron
• Cell bodies at SC but can
leave CNS  synapse m.
• Cranial and Spinal nerves:
ALL spinal n. are LMN but not
all cranial n. are LMN
• aka FINAL MOTOR PATHWAY
 damage: voluntary,
autonomic and reflexive mvmt.

10. UMN LESION LMN LESION
Origin CNS PNS
Common cause Stroke, trauma, infectious
disease, multiple sclerosis, ALS
Trauma, stroke, tumor, polio
alcoholism, ALS
Structures
involved
Motor cortex, internal capsule,
pyramidal tract
Brainstem/ spinal cord, lower
motor neuron/ axon
Voluntary mvmt. Paralysis/ paresis esp. fine
mvmts.
Paralysis