Descending Tracts
part 1
bundles of axon from the cortex or subcortical centers that
come down and causes a response in an effector systems
brings motor decisions from higher centers in the CNS to
lower centers in the CNS
central sulcus (fissure of rolando) is the dividing line
between the sensory and motor cortex.
motor is anterior and sensory is posterior
Descending Tracts 1
, How did neurologists know which areas of the brain were in
charge of which function?
1. by electrical stimulation
2. by observing what neurological deficit presented whenever
there were destructive lesions in the brain
Three different areas of the cortex control the motor system:
primary motor cortex -
precentral gyrus and its
extension medially on the
cerebral hemisphere
pre motor cortex
supplementary motor cortex
Descending Tracts 2
, Pre motor cortex - plans the motor activity and makes a motor
program. It also plans fine movements like when u talk
eg. seeing a cup of coffee and thinking about taking it up
and putting it to your mouth
supplementary motor cortex - concerned with primitive
movements
eg. trunk and hip movements, bilateral movements
🧠 premotor neurons do not have a direct connection with
the muscles. hence it cannot initiate a voluntary
movement
Motor programs are generated in the premotor cortex and these
stimulate neurons in the primary motor cortex.
These stimulated neurons in the primary motor cortex send
axons that eventually come down and connect to neurons that
stimulate the muscles
Descending Tracts 3
part 1
bundles of axon from the cortex or subcortical centers that
come down and causes a response in an effector systems
brings motor decisions from higher centers in the CNS to
lower centers in the CNS
central sulcus (fissure of rolando) is the dividing line
between the sensory and motor cortex.
motor is anterior and sensory is posterior
Descending Tracts 1
, How did neurologists know which areas of the brain were in
charge of which function?
1. by electrical stimulation
2. by observing what neurological deficit presented whenever
there were destructive lesions in the brain
Three different areas of the cortex control the motor system:
primary motor cortex -
precentral gyrus and its
extension medially on the
cerebral hemisphere
pre motor cortex
supplementary motor cortex
Descending Tracts 2
, Pre motor cortex - plans the motor activity and makes a motor
program. It also plans fine movements like when u talk
eg. seeing a cup of coffee and thinking about taking it up
and putting it to your mouth
supplementary motor cortex - concerned with primitive
movements
eg. trunk and hip movements, bilateral movements
🧠 premotor neurons do not have a direct connection with
the muscles. hence it cannot initiate a voluntary
movement
Motor programs are generated in the premotor cortex and these
stimulate neurons in the primary motor cortex.
These stimulated neurons in the primary motor cortex send
axons that eventually come down and connect to neurons that
stimulate the muscles
Descending Tracts 3
