Ascending and Descending pathways Flashcards
what pathway serves touch, proprioceptive info and vibration ?
dorsal column-medial lemniscal pathway
where do the ipsilateral large sensory axons (Ab) of dorsal column pathway enter first ?
the ipsilateral dorsal column of the spinal cord, the white matter tract medial to the dorsal horn.
what information is carried to the brain via the dorsal column pathway
tactile sensation and limb position
what is the dorsal column composed of ?
primary sensory axons and second-order axons from neurons in the spinal gray matter.
where do the axons of the dorsal column terminate ?
in the dorsal column nuclei, which lie at the junction of the spinal cord and medulla
where do the axons from cells of the dorsal column nuclei decussate ?
at the ventral and medial medulla.
which tract do axons of the dorsal column nuclei ascend by ?
within a conspicuous white matter tract called the medial lemniscus ?
what does the medial lemniscus rise through ?
the medulla, pons, and midbrain
which axons of the medial lemniscus synapse with?
with neurons of the ventral posterior (VP) nucleus of the thalamus.
where do thalamic neurons project to ?
specific regions of the primary somatosensory cortex, or S1
what are the lateral pathways involved in ?
voluntary movement of the distal musculature and are under direct cortical control
what are the ventromedial pathways involved in?
control of posture and locomotion and are under brain stem control
name two tracts of the lateral pathways ?
corticospinal and ribrospinal tracts
what is the longest and largest tract in the CNS ?
the corticospinal tract
where do the axons of the corticospinal tract originate ?
in areas 4 and 6 of the frontal lobe, collectively called motor cortex
what areas do the axons from the cortex pass through
through the internal capsule, course through the base of the cerebral peduncle (a large collection of axons in the midbrain), then pass through the pons, and collect to form a tract at the base of the medulla
how would you describe the medullary pyramid
a tract that forms a bulge, running down the ventral surface of the medulla
what is another name for the corticospinal tract ?
the pyramidal tract
where does the pyramidal tract decussate ?
at the junction of the medulla and spinal cord. this is known as the pyramidal decussation
where do the axons in the corticospinal tract collect in the spinal cord ?
in the lateral column of the spinal cord and form the lateral corticospinal tract
where do the corticospinal tract axons terminate ?
in the dorsolateral region of the ventral horns and intermediate grey matter, the location of the motor neurons and interneurons that control the distal muscles. particularly the flexors
