CorticoSpinal and Cortico Bulbar fibers-1 Flashcards
Artery supply of hip and below on Primary motor cortex
Anterior Cerebral artery
Broadman’s area 4 overlaps largely with
the precentral gyrus and the anterior paracentral, lobule
Premotor cortex receives projections from
posterior parietal area BA-5,7 Basal Ganglia via thalamus cerebellumvia thalamus
primary motor cortex receives input from
PSC - BA-3,1,2 Poterior parietal cortex BA-5,7(integrates sensory info for motor planning in concert with frontal areas Basal ganglia via thalamus and premotor area Cerebellum via thalamus
the lateral aspects of the premotor cortex project to _______ and also contribute to ____________
pirmary motor cortex, corticospinal and coritcobulbar tracts.
main function of the lateral corticopsinal tract is
voluntary contraction and relaxation of muscles but has a stronger influence over flexor muscles.
mental rehearsing of a sequence is done by the
supplementary motor area
finger flexion is done by the
motor cortex and somatosensory cortex
sequence of finger flexions shows activity in
both supplementary and motor/somatosensory regions
Lateral corticospinal tract originates in
pyramidal somata of layer 5 of the precentral gyrus and paracentral lobule (Broadman’s area 4)
End of the corticospinal tract is
the contralateral spinal ventral horn where the axons of upper motor neurons synapse with the alpha and gamma lower motor neurons
route of the corticospinal tract
cortex, corona radiata, internal capsule, crus cerebri, basilar pons, pyramids(medulla), pyramidal decussation, corticospinal tracts in spinal cord, synapses in alpha and motor neurons ins spinal ventral horn
upper motor neurons commonly release
glutamate onto AMPA receptors either directly or indirectly sitmulating alpha and gamma lower motor neurons
damage to corticospinal rostral to the pyramidal decussation produces
contralateral paresis
damage to corticospinal tract caudal to the decussation produces
ipslateral paresis
bilateral damage to the motor cortex or corticospinal and corticobulbar axons and initially lead to
muscular flaccidity and arreflexia which is called shock, (spinal shock if arising from spinal injury
generally shock riddled spinal circuits caudal to lesion regain
function after a few weeks
upper motor neuron lesion sumptoms
above DEC-contralateral below DEC-ipsilateral -Hyperreflexia- brisker than normal reflex -Extensor plantar response -first flaccid paralysis and later spastic paralysis(hypertonia) -no wasting muscle because 2nd motor neuron is not impaired -Clonus
Lower motor neuron lesion
ipsilateral Hyporeflexia/areflexia- due to disruption of the eferent motor limb of the sensory motor reflex arcs. Hypotonia or atonia flaccid paralysis or paresis wasting of muscles Fasiculations fibrillations Examples ALS, Peripheral nerve trauma.
Brown Sequard Syndrome
-CS tract- below lesion, upper motor syndrome usually occurs ipsilaterally ALS- contralateral loss of pain and temp DCML- loss of touch, vibration, proprioception ipslaterally below lesion LMN- Segmental syndrome occurs at the level of the lesion
Paraplegia
ALL BILATERAL -Hyper reflexia -Extensor plantar response -transient flaccid paralysis below level of lesion followd by spastic paralysis -increased clonus -early transient retention of urin with painless destension of the bladder and overflow -paraplegia in flexion -loss of all somatosensation from below the lesion.
Motor Homonuculus man
