Motor systems Flashcards
Alpha motoneuron
contact muscle fibers, final pathway brain uses to control motor output
gamma motoneuron
class of motoneuron that only innervates intrafusal fibers
motor unit
a single alpha motoneuron and all the muscle fibers it innervates
muscle spindle
composed of intrafusal fibers that measure the length of the muscle
golgi tendon organ
detect muscle tension, innervated by 1b afferents
myotatic reflex
stretch reflex, group 1a fibers travel up dorsal horn, contact interneurons in intermediate zone, and then contact the alpha motoneuron in the ventral horn to innervate the same muscle that the signal came from, a monosynaptic reflex
flexor reflex
flexors are excited while extensors are inhibited, example is removing hand from hot stove
crossed extensor reflex
extensors are excited on the opposite side of the body that has excited flexors, example is stepping on a nail
corticobulbar projections
terminate in the brainstem, influence cranial nerve motor nuclei via pontine and medullary reticular formations
corticopontine projections
terminate in pontine nuclei, influence cerebellum
red nucleus
source of the rubrospinal tract
ventromedial tracts
maintain posture by controlling axial skelelton, limb girdles, and proximal limb
_________tract stimulates flexors, inhibits extensors
reticulospinal
________tract stimulates extensors, inhibits flexors
vestibulospinal
_________ tract is involved with muscles of the neck and upper trunk; orienting responses
tectospinal
dorsolateral tracts
control distal muscles of the limb, voluntary movements
_________tract affects forelimb muscles
rubrospinal
_________tract affects distal muscles of both limbs
corticospinal
motor component of the corticospinal tract
primary motor cortex (MI) in the brain
non-motor component of the corticospinal tract
somatic sensory cortex (SI) in the brain
central pattern generators
operate at the local spinal level and generate a basic rhythmic motor output, modulated by tectospinal, rubrospinal, and corticospinal tracts, interconnected CPGs provide the basic rhythm of locomotion
sensory-motor basal ganglia loop
sensory-motor and premotor cortex>putamen>global pallidus and substantia nigra>pars reticulata>ventrolateral thalamus
limbic basal ganglia loop
limbic cortex>ventral striatum>ventral pallidum>mediodorsal thalamus
cerebrocerebellum input
pontine nuclei
cerebrocerebellum output
dentate nucleus, then red nucleus, motor thalamus, motor and premotor cortex
cerebrocerebellum fxn
planning movements and fine motor control
spinocerebellum input
spinal cord, vestibular n, trigeminal n.
IT’S THE MOST WONDERFUL TIME
OF THE YEARRRRRRR!!!!!!!!
spinocerebellum output
fastigial, globose, emboliform nuclei, then to brainstem motor centers
spinocerebellum fxn
- vermis: posture and locomotion
- medial hemisphere: motor coordination of extremities
vestibulocerebellum input
vestibular nerve and nuclei
vestibulocerebellum output
vestibular nuclei
vestibulocerebellum fxn
equilibrium, coordination of head and eye movements
rostral cerebellar peduncle:
output to red nucleus and VL thalamus
middle cerebellar peduncle:
input from pons
caudal cerebellar peduncle
input from vestibular nuclei and spinal cord
deep cerebellar nuclei
generate outputs from the cerebellum to other brain regions
