Physiology II for pharmacy students
Sheet no. 4: motor tracts Dr. Faisal Mohammad
done by: Liliana Al-qadi. Checked by: Qabas Mansour.
Before you start: this sheet does NOT include all of the pictures in the
slides, and you need to check them in order to understand the motor tracts.
Spinal cord functions as a reflex center and has other functions represented
in sensory and motor tracts, in the previous sheet spinal sensory tracts were
explained. And in this s
The pathway of the spinal motor tract in general:
Motor Tracts of Spinal Cord (descending tract):
These tracts are arranged in systems: pyramidal and extrapyramidal
systems.
1
, Pyramidal tracts:
1.Corticospinal tract: has two divisions: Anterior & Lateral.
In the lateral division, efferent nerves descend from the motor cortex (pre
central gyrus) down and decussate at the level of medulla oblongata. the
-
nerve decussation area forms a pyramid like structure and so these tracts are
=
called pyramidal tracts.
functions of the corticospinal tract: control the precise fine voluntary
movements of distal muscle of the limbs and tongue, ex: writing & talking.
Remember: Since these tracts decussate then they are contralateral, never
forget.
NOTE: more than 90% of fibers do
cross and less than 10% do not, these
fibers are located in the Anterior
column (division) although they cross
at the level of the spinal cord.
.
2.corticobulbar tract: motor neurons descend
from the cortex to the nuclei of cranial nerves
in the brainstem. It is located in the
extrapyramidal area.
Extrapyramidal tracts: tracts that do not cross
over at the level of the pyramids in the
medulla, also mentioned as indirect tracts.
nsidered as a tract by itself, not
pyramidal not extrapyramidal.
2
Sheet no. 4: motor tracts Dr. Faisal Mohammad
done by: Liliana Al-qadi. Checked by: Qabas Mansour.
Before you start: this sheet does NOT include all of the pictures in the
slides, and you need to check them in order to understand the motor tracts.
Spinal cord functions as a reflex center and has other functions represented
in sensory and motor tracts, in the previous sheet spinal sensory tracts were
explained. And in this s
The pathway of the spinal motor tract in general:
Motor Tracts of Spinal Cord (descending tract):
These tracts are arranged in systems: pyramidal and extrapyramidal
systems.
1
, Pyramidal tracts:
1.Corticospinal tract: has two divisions: Anterior & Lateral.
In the lateral division, efferent nerves descend from the motor cortex (pre
central gyrus) down and decussate at the level of medulla oblongata. the
-
nerve decussation area forms a pyramid like structure and so these tracts are
=
called pyramidal tracts.
functions of the corticospinal tract: control the precise fine voluntary
movements of distal muscle of the limbs and tongue, ex: writing & talking.
Remember: Since these tracts decussate then they are contralateral, never
forget.
NOTE: more than 90% of fibers do
cross and less than 10% do not, these
fibers are located in the Anterior
column (division) although they cross
at the level of the spinal cord.
.
2.corticobulbar tract: motor neurons descend
from the cortex to the nuclei of cranial nerves
in the brainstem. It is located in the
extrapyramidal area.
Extrapyramidal tracts: tracts that do not cross
over at the level of the pyramids in the
medulla, also mentioned as indirect tracts.
nsidered as a tract by itself, not
pyramidal not extrapyramidal.
2
