4.17. Suprasegmental Motor control Flashcards
basic pathway of segmental control (starting from motor areas in the brain to the muscle groups)
axial muscles innervated by __ (ventromedial/dorsolateral) neurons
limb muscles innervated by __ (ventromedial/dorsolateral) neurons
Motor cortex, premotor areas and supplementary motor areas project down to the spinal cord (specifically either directly to the lower motor neurons in the ventral horn, or they project to interneurons that then project to groups of LMNs)
Axial muscles are innervated by the ventromedial motor neurons
Limb muscles are innervated by dorsolateral motor neurons
The lateral neurons doesn’t really exist at the thoracic level (obviously there’s no need for them); they only exist in the cervical and lumbar spine
**that little green interneuron circled in red projects to limb muscles and innervates multiple segments**
3 types of motor skills in clinical medicine (plus examples of each)
Gross motor skills: walking, running, etc (so basically things that involve using major muscle groups)
Fine motor skills: writing
Visuo-motor skills: e.g. using blocks to build things (constructing; higher order functions compared to fine motor skills)
descending motor pathways
Corticospinal Tracts
Corticobulbar Tracts
Rubrospinal Tracts
Tectospinal Tracts
Vestibulospinal Tracts
Reticulospinal Tracts
pathways of descending motor pathways
(e.g. Corticospinal Tracts: Brain to S.C.)
Corticospinal Tracts: Brain to S.C.
Corticobulbar Tracts: Brain to brainstem
Rubrospinal Tracts: Red nucleus to S.C.
Tectospinal Tracts: Superior colliculus to S.C.
Vestibulospinal Tracts: Vestibular nuclei to S.C.
Reticulospinal Tracts: Reticular nuclei to S.C.
LMNs to the face, head and neck are located in the ___
The LMNs to your limbs are located in the ___
brainstem
ventral horn of the spinal cord
pathway of lateral corticospinal tracts
A lesion in the dorsolateral SC will cause weakness ___ (contralaterally or ipsilaterally)
cortex >> internal capsule >> cerebral peduncles >> basis pontis >> pyramids >> pyramidal decussation >> dorsolateral spinal cord (as lateral corticospinal tract) >> limb muscles
A lesion in the dorsolateral SC will cause weakness contralaterally
pathway of anterior corticospinal tracts
a lesion in the anteromedial SC will cause weakness ___ (contralaterally/ipsilaterally)
cortex >> internal capsule >> cerebral peduncles >> basis pontis >> pyramids >> anteromedial spinal cord (as anteromedial spinal cord) >> axial muscles
Lesion in the anteromedial spinal cord will cause weakness ipsilaterally
pathway of corticobulbar tracts
corticobulbar tracts control output to the ___, ___, and ___
These fibers start out in the cortex then go down the internal capsule (probably the genu), through the cerebral peduncles and from there, they could either continue downwards ipsilaterally or if they reach their target, they can cross at that level
face, head, neck
nuclei of cranial nerves __, __ and __ receive bilateral innervation
Nuclei of cranial nerves 5, 7 and some of 12 receive bilateral innervation
briefly describe the innervation of the facial nerve nucleus (differences between upper and lower face innervation)
Bell’s palsy (signs on the face; if forehead is affected or not)
what happens if you have a lesion in the motor cortex?
Lower face only has unilateral innervation; upper face has bilateral innervation
Bell’s palsy: LMN facial weakness; the entire face including the forehead is affected
If there’s a lesion in the motor cortex, you’ll get contralateral face weakness, but the forehead will be spared since it’s doubly innervated
pathway of rubrospinal tracts
if you lost innervation through the corticospinal tracts, which functions would you preserve and which ones would you lose?
red nucleus >> (crossing at level of origin) >> pons >> medulla (raustral >>caudal) >> lateral anterior horn of spinal cord >> flexor muscles of limbs
preserve: gross motor functions
lose: fine motor functions
tectospinal tract pathway
Superior colliculus >> (cross at level of origin) pons >> medulla >> (medial) cervical spinal cord >> axial muscles ( plus vision)
function of tectospinal tracts
reflexive head movements related to eye movements
vestibulospinal tract types
pathway of each
medial and lateral vestibulospinal tracts
Medial vestibulospinal tract descends bilaterally in the tegmentum; innervates the lower medulla and cervical spinal cord (anterior horn)
Lateral vestibulospinal tract descends unilaterally/ipsilaterally to the entire spine; innervates extensor muscles
reticulospinal tract pathway
function of reticulospinal tract
Pontine reticular formation >> medulla >> (medial) cervical spinal cord
innervation of axial muscles most likely since its medial
posture definition
2 components of posture
Posture: Position of a person’s body parts
Components:
Orientation – positioning of body parts in relation to each other
Balance – active resistance to external forces on the body
sway (definition)
higher centers that control balance (3 of them)
sway: deviation of body position away from a stable equilibrium
- Vestibular system
- Cerebellum
- Cerebral cortex
locomotion definition
role of central pattern generator; where does CPG activity come from?
ability to move in space
(Locomotion is basically automatically regulated (central pattern generators) )
spinal cord
motor equivalence
The idea that motor cortex controls the task of motor function, but the actual action is up to other parts of the body
In the primary motor cortex (precentral gyrus), the ___ and the ___ have the most representation because they do a lot of fine motor functions
3 main brain areas involved in voluntary movement
In the primary motor cortex (precentral gyrus), the hand and the face have the most representation because they do a lot of fine motor functions
Premotor cortex (right in front of the primary motor cortex); supplementary motor cortex in the interhemispheric fissure; primary motor cortex
what are the sensory areas (near the motor areas) that are also involved in voluntary movement?
postcentral gyrus (primary somatosensory) and posterior parietal cortex (more higher order)
other areas involved in voluntary movement (hint: the things he was saying were extra-pyramidal)
Basal ganglia
Thalamus
Brainstem
Cerebellum
(pyramidal tracts and extra pyramidal system)
The ___ lobe is important for making a sensory picture of the world
posterior parietal lobe
which area of the brain is linked to the posterior parietal lobe and is involved in making multiple sensory maps? (hint: its one of the 3 motor areas)
pre-motor cortex
which area of the brain is responsible for executing voluntary movement?
frontal lobe (premotor cortex + prefrontal cortex)
define readiness potential
Readiness potential: pre-set plan of action in your brain before you execute an action
coordination of muscle movements following the firing of motor neurons is done at the level of the ___
spinal cord
