Anatomy - PCML Flashcards
where do fibers from the DRG go into the spinal cord in PCML
posterior horn
large-diameter fibers relay what kind of info
touch, flutter, vibrations, proprioception
how do fibers of PCML enter the spinal cord
via medial division of posterior root
once in the spinal cord where do fibers of the PCML go
synapse onto second order neurons at, above, or below level of entry
the largest set of branches of PCML from the DRG do what once in the spinal cord
ascend cranially to form the fasciculus gracilis or fasciulus cuneatus (posterior/dorsal columns)
describe the topographical organization of the posterior columns
from medial to lateral:
sacral/coccygeal levels –> lumbar and thoracic levels below T6 –> thoracic levels above T6 –> low cervical levels –> upper cervical levels
what makes up the fasciculus gracile
sacral and coccygeal levels, lumbar and thoracic levels below T6
what makes up the fasciculus cuneatus
thoracic levels above T6, lower cervical, and upper cervical levels
spinal cord lesions of the PCML result in ____
ipsilateral loss of discriminative, positional, and vibratory tactile sensations at or below the level of injury
if patient has a wide based stance and is placing feet to the floor with force, what might you susepct
damage to PCML (they are trying to create the missing proprioceptive input)
describe the segregation of tactile inputs within the nuclei gracile and nuclei cuneatus and also the VPL
the core clusters receive inputs from rapidly and slowly adapting afferents
the outer shells receive input from muscle spindles, joints, and pacinian corpuscles
describe the tract of the PCML once it hits the medulla
the axons cross in the medulla as internal arcuate fibers and then ascend as the medial leminiscus to the thalamus contralateral to where the fibers originated in the spinal cord
how does the organization of the upper and lower extremities change in the pons for the PCML
as the medial leminiscus ascends it rotates laterally in the pons which causes the upper extremity fibers to lie medially and the lower extremity fibers to lie laterally
where does the medial leminiscus terminate in the PCML
the ventral posterolateral nucleus (VPL)
what is the arterial supply for the PCML in the spinal cord and then once its gets to the medulla
spinal cord: posterior spinal a.
medulla: anterior spinal a.
