Roles in
Postural control
Brainstem
Motor systems
Ventromedial Pathway
Ensure the generation of coordination
of appropriate muscles to control the
body’s position and movement in space
Pyramidal tracts:
concerned with voluntary motor
activities of the body.
Corticobulbar pathway:
connecting motor cortex in the cerebral cortex to
the medullary pyramids
Function: muscles of the face, head and neck.
Innervates: v,vii, motor part of x,xi,xii.
Extrapyramidal pathway:
- Adjust body posture to provide stable
background for movement.
- Concerned with grosser movements
and posture.
Vestibulospinal tract:
▪ Carries information from vestibular nucleus
for reflex control of equilibrium .
Cerebellum:
▪ Spinocerebellum :
- Regulates the postural reflexes by modifying
muscle tone.
- It facilitates the gamma motor neurons in the
spinal cord via cerebello-vestibulo-spinal
neurons in the spinal cord.
- Cerebello-reticulo-spinal tracts :
The gamma motor neurons reflexly modify the
activity of alpha motor neurons and thus
regulate the muscle tone.
- Thus, cerebellum forms an important site of
linkage of alpha-gamma systems responsible
for muscle tone
Basal ganglia:
▪ Control the muscle tone.
▪ Basal ganglia are responsible for the
coordination and integration of impulses
for these reflex activities.
Tectospinal tract:
▪ Originates in tectum for control of head and
eye movements .
Medial reticulospinal tract:
▪ Originates in reticular formation for
maintaining posture by activation of
extensors.
Lateral reticulospinal Rubrospinal tract:
pathway Originates in reticular formation
for maintaining posture by activation of
flexors
Visual pathway:
Rubrospinal tract:
▪ The rubrospinal tract begins in the
magnocellular red nucleus.
▪ The rubrospinal tract terminates in the
cervical segments of the spinal cord 24 and
therefore only innervates upper limbs.
▪ It is believed that in humans it is responsible
for arms swinging while walking or baby
crawling motion.
Has neurons that are specialized in
responding to movement of the
retinal image across the retina.
Vestibular apparatus:
Maintaining posture and equilibrium
through statokinetic reflexes.
semi-circular canals
Superior Semicircular Canal:
gives response to rotation in anteroposterior plane
(transverse axis), i.e. front to back movements like
nodding the head while saying ‘yes – yes’.
Horizontal Semicircular Canal:
gives response to rotation in horizontal plane
(vertical axis), i.e. side to side movements (left to
right or right to left) like shaking the head while
saying ‘no – no’.
Posterior Semicircular Canal:
gives response to rotation in the vertical
plane (anteroposterior axis) by which head is rotated
from shoulder to shoulder.
Postural reflexes:
The postural reflexes help to maintain the
body inupright and balanced position.