DESCENDING SPINAL PATHWAY Flashcards
Descending spinal pathway
somatic motor (skeletal muscles)
What are lower motor neurons
motor neurons located in
1. spinal cord (ventral horn) for spinal nerves
2. brain stem for cranial nerves
What are upper motor neurons
motor neurons located in
1. cerebral cortex (pyramidal system)
2. brainstem (extra pyramidal system)
Pyramidal system (cortico spinal tract) function
VOLUNTARY AND CONSCIOUS
UMNs in cerebral cortex
LMNs in spinal cord ventral horn/ brainstem
Where is the first order motor cortex?
pre central gyrus
Where does the pyramidal system originate from?
cerebral cortex
What is the pathway of pyramidal system
- pre central gyrus
Corona radiata
-> 2. internal capsule
-> 3. midbrain: crus cerebi
-> 4. medulla: pyramids
-> 5a) decussate to lateral CST 90%
5b) do not decussate , goes to ventral CST, then decussate at anterior CST 10%
Extrapyramidal system function
controls muscle tone , posture, reflex movements
INVOLUNTARY AND SUBCONSCIOUS
Where does the extrapyramidal system originate from
brain stem
What are the tracts of extrapyramidal system?
- rubro-spinal tract
- tecto-spinal tract
- vestibulo- spinal tract
- reticulo-spinal tract
What is the rubro-spinal tract?
THINK RED NUCLEUS
- from red nucleus at the level of midbrain
- excitatory to flexor muscles: upper limb muscle tone and movement
What is the tecto-spinal tract?
- from tectum, at the level of midbrain
- mediate reflex stimulus
- in response to visual stimulus
What is the vestibulo-spinal tract?
- from vestibular nuclei
1. lateral vestibulo-spinal tract - control extensor (antigravity) muscles
- tone and eqm
- maintenance of posture and balance
- medial vestibulo-spinal tract
-control correct position of head and neck
What is the reticulo-spinal tract?
- from reticular formation located in pons and medulla
- controls muscle tone/ voluntary movemnet
- reflex activities
-CVS, Respi
