Motor Systems Flashcards
describe the sensory reflex arc
- Sensory input from the skin travels via the afferent nerve through the spinal cord via an interneuron, and leaves the spinal cord to travel to the muscle (effector) via the efferent nerve.
in terms of reflex arcs, all movements contain what?
- All movements include 1 or more reflex arc.
what do spinal reflex arcs avoid?
the brain
where is the primary motor cortex?
(Brodman area 4) in the posterior frontal cortex.
what can be found in the primary motor cortex?
o The motor homunculus is here (more fine motor movements are bigger on the homunculus)
role of premotor cortex
processes external environment
what is at brodmann area 4?
primary motor cortex
what is found at the outer area of brodman 6?
premotor cortex
where is the premotor cortex?
outer area of brodman 6
role of supplementary motor area
prepares plan
where is the supplementary motor area?
medial area of brodman 6
what is at medial brodman 6?
supplementary motor area
role of basal ganglia
initiates movement and suppresses unwanted movement
name a condition the basal ganglia is important in
parkinsons
role of cerebellum
coordinates ingoing movement
two types of spinal tracts
ascending and descending
descending spinal tract
corticospinal tract
is the corticospinal tract ascending or descending
descending
where is the corticospinal tract?
from cerebellum to spinal cord
role of corticospinal tract
Corticospinal tract (from cerebellum - decussation of the pyramids in the medulla – conveys motor commands to the muscles)
which spinal tract is is responsible for:
decussation of the pyramids in the medulla and conveying motor commands to the muscles?
corticospinal tract
ascending spinal tracts
spinocerebellar tract
dorsal columns
spinothalamic tract
is the spinocerebellar tract ascending or descending?
ascending
is the spinothalamic tract ascending or descending?
ascending
are the dorsal columns ascending or descending?
ascending
role of spinocerebellar tract
to cerebellum – provides sensory feedback to motor structures allowing for real-time error correction)
which tract is this?
to cerebellum – provides sensory feedback to motor structures allowing for real-time error correction
spinocerebellar
role of dorsal columns
(proprioception of fine motor movements)
which tract is this?
(proprioception of fine motor movements)
dorsal columns
role of spinothalamic tract
gross movements
what tract is this?
gross movements
spinothalamic tract
example reflex - tapping a ligament
- Tap a ligament
- Stretches muscle and muscle spindle
- Mechanosesnsitive strcutre
- Fires AP when stretched to a certain point
- Travels along 1a (alpha) afferent neuron to the spinal cord etc. (interneuron/relay neuron) connecting to efferent neuron to muscle for a response (e.g. pull away)
- Alpha motor neuron: makes the muscle contract
- Gamma motor neuron: causes contraction of the muscle spindle
Sensitive to stretch
describe lower motor neurons
- In reflex arc
- Out of ventral route
- All movements follow this wiring
describe upper motor neurons
- Allow exertion of voluntary control
- Originate in the brainstem and cortex
- Synapse with lower motor neurons rather than lower motor neurons directly (usually)
where are lower motor neurons?
in reflex arc out of ventral route
where are upper motor neurons?
originate in brainstem and cortex
what do upper motor neurons allow?
exertion of voluntary control
what do upper motor neurons synapse with?
- Synapse with lower motor neurons rather than lower motor neurons directly (usually)
example sensorimotor pathway - nociceptors
- Nociceptor
- Dorsal root ganglion
- Posterior horn
- Interneuron
- Anterior horn
- Alpha motor neurons
- Muscles
order of spinal cord segments from head to toe
- Cervical
- Thoracic
- Lumbar
- sacral
