Descending Neural Pathways Flashcards
what does the body need to do a purposeful movement
- goal or purpose
- activation of relevant movement
- feedback of movement
- refinement/correction of movement
- cessation on completion
where is the motor cortex located and what are its sub areas
- anterior to central cortical sulcus
- primary motor area
- premotor area
- supplementary area
primary motor cortex
topographical representations mapped by electrical stimulation of motor cortex areas
- more than half the primary motor cortex controls hands and muscles of speech
- excitation of a single umn usually excites a specific movement not one specific muscle
PATTERNS
Premotor area
similar topographical regions to primary motor cortex
nerve signals give more complex patterns of movement
supplemental motor area
contractions elected are often bilateral
usually functions together with premotor area
- gives background movement onto which promotor and primary motor cortex and finer control
rehearsal - planning - action
corticopspinal tract
transmission of signals from motor cortex to muscles
- carriers signals direct from cortex to spinal cord
- cortex to pyramids of medulla to (majority) cross in lower medulla and then go on to the lateral corticospinal tracts and mainly terminate on interneurones
ONES THAT DO NOT CROSS PASS IPSILATERALLY IN VENTRAL CORTICOSPINAL TRACTS
conscious movement - lateral pathways
principally controlled by the cerebral cortex via two corticospinal tracts
general control of voluntary movement
mainly associated with control of distal muscles
unconscious movement - ventromedial pathways
principally controlled in the brainstem
control of posture and rhythmic movements associated with locomotion
control axial and proximal muscles
extra pyramidal tracts
reticulospinal tracts - posture, locomotion and autonomic function
vestibulespinal tracts - balance and posture
rubrpspinal tract - red nucleus, influences by cerebellum and reticular nuclei, excitatory flexors
tectospinal tract - head and neck moevemtns for visual tracking
control of motor functions by the brains stem
- extension of the spinal cord upward into the cranial cavity
- control of respiration, CV system
- Partial control GI function
- Control of many stereotyped body movements, equilibrium, eye, movements
serves as a way station for command signs;s for higher neural centres
posture
position of the body and its parts relative to each other. is a compromise between balance and movement
how do we maintain balance
posture is adjusted predominantly by involuntary movement driven both predictively (postural set - preparing) and reactively (compensation - falling)
- is controlled and driven by the brainstem and is where the postural set is governed
what are the sensory inputs to postural control
muscle proprioceptors (detect changes in muscle length and tension)
sense of balance derived from movements fo the head relative to the earths gravitational field (vestibular apparatus)
visual inputs (detecting movements in visual field representing movement of the body
INTEGRATED IN THE BRAINSTEM
reticular nuclei
- pontine (in pons)
- medullary (in medulla)
Mainly function antagonistically to each other
vestibular nuclei
every other place in the brainstem
