Functions Of Descending Motor Tract Flashcards
GR: The name of the pyramidal tract
Because some fibers arise from the pyramidal (Betz) cells present in motor area 4
Functions if pyramidal tract
- Controls fine skilled motor movements especially in the distal joints
- Shares with extrapyramidal tract in gross movements and postural adustment as background for fine movements
- Facilitatory to superficial & deep reflexes
- Inhibits primitive withdrawal reflex
- Conrticobulbar tract controls lateral eye movemts
Mention parts of medial brain stem
Work via vertical corticospinal tract
PRS & MRS, vestibulospinal, tectospinal tracts
Describe termination of medial brain stem pathways
-Terminate on interneurons in ant horn of spinal cord to control axial & proximal muscles
-Some terminate directly on motor neurons to control axial muscles
Describe lateral brain stem pathway
Arise from red nucleus of midbrain which has a somatotopic representation like area 4 but less fine, terminate on interneurons in ventral horn of spinal cord controlling distal muscles, it excited flexor & inhibits extensor muscle, may be a weak alternative in fine skilled movement in case of pyramidal lesion
Enumerate functions of extrapyramidal tract
- Control gross movements if axial & proximal muscles.
- Provide postural background for performance of fine skilled movements
- Associated with basal ganglia in semiautomatic movements
- In selective corticospinal tract lesion, rubrospinal tract can control fine movements of hand & wrist but not fingers.
- Regulation of muscle tone
- Med tectospinal —reflex head turning in response to sound, lateral tectospinal —protective eye reflexes, head turning in response to visual stimuli.
- Vestibulospinal tract activate antigravity muscles.
- Autonomic functions
Describe autonomic functions of extrapyramidal tract
- Respiratory center to AHCs of respiratory muscles
- Vasomotor tract to LHCs in thoraco-Lumbar region
- Sweat secretion (from heat regulating center in hypothalamus)
Compare pyramidal to extrapyramidal with respect to termination & when function starts
Pyramidal, terminate on cranial nerve nuclei & alpha & gamma (AHCs) , begins one year after birth
Extrapyramidal, terminate on alpha & gamma neurons, during first year
Mention site of termination of medial & lateral motor systems
M, medial or ventral portion of anterior horn
L, lateral portion of anterior horn