subcortical control of movement Flashcards
what is the Basic layout of the subcortical motor
system
- spinal cord
- medulla
- pons
- cerebellum
- midbrain
- thalamus
- basal ganglia
how do muscles contract
Stretching a muscle is detected in the muscle and
leads to increased activity in sensory neurones that in
turn leads to an increase in the activity of motor
neurons that innervate the same muscle, while
inhibiting the motor neurons that innervate
antagonists
features of a reflex
rapid automatic control of movement.
* little or no voluntary control.
* some are very simple:
* stretch reflex.
* some are more complex:
* swallowing, breathing.
* these mainly happen in the spinal cord and low in the brain
stem.
3 parts of the brain stem + location
the brainstem sits at the top
of the spinal cord and is
made of three parts:
1. medulla
2. pons
3. midbrain
what are the 2 important brain stem nuclei groups
reticular formation
vestibular nuclei (VN)
what is the vestibular nuclei (VN)
The vestibular nuclei (VN) are the
nuclei for the vestibular system
and are located in the brainstem.
what is the reticular formation
The reticular formation is a set of
interconnected nuclei that are
located throughout the brainstem.
what is the Vestibulospinal tract
The vestibulospinal tract originates
in the vestibular nuclei. They send
most of their output to the spinal
cord and to the muscles that move
the eyes.
what is the vestibular system?
The vestibular system is the
sensory system that provides the
sense of balance and spatial
orientation for the purpose of
coordinating movement with
balance.
what is the Vestibulospinal tract function
the function is to alter posture
what is the reticular formation?
he reticular formation is a set of
interconnected nuclei that are
located throughout the brainstem.
* It is a very old part of the brain
what is the reticulospinal tract
The reticulospinal tract originates in
reticular formation.
* These tracts function in maintaining
tone, balance, and posture
functions of the Reticulospinal Tract
the reticulospinal tract functions to maintain
our posture. Before we lift a weight with our
arm, muscles of the leg are excited to
support our body posture. This postural
control is via the fast-acting excitatory
action of the reticulospinal tract
features of the cerebellum
the cerebellum has a very
conserved, highly folded
structure in all animals
* 10% volume of the brain.
* More than neurones than
the cortex.
* 69B v 16B
* input:output connections
ratio.
* 40:1
the 3 parts of the cerebellum
superior cerebellar peduncle
middle cerebellar peduncle
inferior cerebellar peduncle
features of the superior cerebellar peduncle
- efferent (out) pathway to the red
nucleus and the cortex (via the
thalamus) & sup colliculus.
functions of the middle cerebellar peduncle
- most fibres originate in the pons
- input from sensory, visual, vestibular
and motor systems. - but its largest input is from the cortex.
features of the inferior cerebellar peduncle
carries information to and from the the
spinal cord (and the body) and
vestibular nuclei.
The red nueclues
The red nucleus is a roughly spherical
collection of cell bodies in the midbrain.
It is called the red nucleus because it is
extremely vascular. In fresh tissue the
red nucleus is distinctly pinker than the
surrounding tissue.
The red nucleus receives a very large
input from the cerebellum and from the
primary motor cortex.
location of the rubrospinal fibers
rubrospinal fibers that originate in the red
nucleus cross the midline immediately after
exiting the nucleus. Then they course in the
ventrolateral part of the brainstem to the cord.
In the cord rubrospinal fibers occupy the same
part of the white matter as the corticospinal
tract.
where do the rubrospinal fibers terminate
Rubrospinal fibers terminate primarily in the
cervical and lumbar enlargements of the
cord, which contain motor neurones for
muscles in the fore- and hindlimbs,
respectively.
functions of the basal ganglai
movement regulation
* skill learning
* habit formation
* reward systems
* selection of appropriate
behaviours
* self-initiation of
behaviours
describe the 2 pathways of the BG
he DIRECT pathway
that runs DIRECTLY
through the basal
ganglia
- the INDIRECT
pathway takes a
longer loop through
the basal ganglia
features of the direct loop
short loop though the basal
ganglia.
* has excitatory effect on
cortex.
* Net effect is pro-movement.