Are the cell bodies for the LMNs for the extensors generally found dorsally or ventrally in the spinal cord?
Ventrally, the flexors are found dorsally
Can motor neuron pools extend over multiple spinal segments?
What two areas does the cortex send signals to other than the brainstem leading to the spinal cord? Where does the signal go from each of these?
Basal Ganglia-to the thalamus back to cortex
Cerebellum-to the thalamus and to brainstem and to spinal cord. The thalamical tract goes back to the cortex while the brainstem tract goes to the spinal cord
What are the major brainstem pathways that affect LMNs other than the corticospinal? What do they generally do?
Reticulospinal-awareness and arousal
Rubrospinal-comes from Red nucleus
Tectospinal-located at the top of the midbrain, turns head in response to noise or light
Which tracts contribute to the flexors, and which to the extensors in the spinal cord?
Flexor-Corticospinal, rubrospinal, medullary reticulospinal
Extensors-Vestibulospinal and pontine reticulospinal
What areas of the brain give rise to the corticospinal tract?
Premotor cortex, Primary motor cortex, Primary sensory cortex, Supplementary motor area
What area of the brain modulates the activity of the corticospinal tract?
The posterior Parietal Cortex
What areas of the body have the most area in the motor cortex dedicated to them?
What occurs in infants that causes the Babinski sign to go away?
Myelination fo the Upper Motor Neurons
Where do most motor cranial nerve LMNs receive their upper motor neuron stimulation from? What is the exception? How does it manifest?
Most LMNs of the CNs receive their stimulation from UPNs from both cortices, but LMNs projecting to the lower face from CN VII are stimulated by UPNs from the contralateral cortex. It manifests in that if there is an UMN lesion the opposite side or smile is pulled down, while the ipsilateral side is pulled up. If it is a LMN lesion, the ipsilateral side will be pushed down, while the opposite side goes up.
What are the signs of a LMN lesion?
Atrophy of the muscel
What are the signs of a UPN lesion?
Paralysis or paresis