Ascending spinal cord Flashcards
At what levels does the fasciculus gracilis exist?
all levels of the spinal cord
At what level does the fasciculus cuneatus exist?
t1-t6 and c1-c8
In the dorsal column pathway, axons of second order neurons travel as what?
internal arcuate fibers. They cross in the midline to form the medial lemniscus
What is the tract of the internal arcuate fibers in the DCP?
they cross in the midline to form the medial lemniscus, which ascends through th emedulla, pons, and midbrain, and terminates in the contralateral ventral posterolateral nucleus of the thalamus.
Where do the third order neurons go in the DCP?
They travel in the thalamus in the internal capsule and terminate in the sensorimotor cerebral cortex (area 312 of the post central gyrus)
What happens to the first order neurons in the DCP?
sensory fibers from the upper extremity use the fasciculus cuneatus to get to the nucleus cuneatus. Sesnroy fibers from the leg use fasciuculus gracilus to get to the nucleus gracilus.
From medial outward, describe the key sensory or ascending tracts of the spinal column
f. gracilus, f cuneatus, dorsal spinocerebellar, spinothalamic tract, ventral spinocerebellar tract
What is romber’s sign?
Damage to DCP, patient is asked to stand with feet together, if the patient requires vision to stand steadily then it’s a positive sign. Patients have sensory ataxia, not cerebellar ataxia.
What is the true origin of the spinothalamic tract?
Nucleus proprius in dorsal horn
Where do fibers in the spinothalamic tract cross?
Fibers from the nucleus proprius cross the middline in the anterior commissure of the spinal cord and pile up in the lateral and part of the anterior funiculus
Where does the nucleus synapse?
In the VPL and in area 312
How are the fibers of the STT organized? Why does it matter?
The sacral fibers are the most lateral, so they are the last to be destroyed by a syrinx (sacral sparing of pain and temp) (a type of cyst). The syrinx wipes out the spinothalamic fibers, creating a “vested” loss of sensation.
Where does Clark’s nucleus exist?
C8-L2
