spinal cord Flashcards
The word dermatome comes from two Latin words which mean what?
Derma = skin; tome=slice
the intervertebral foramen is what?
a hole which nerves emerge from the bony protection of the spinal cord; the start of the PNS
the central canal (CNS) contains what?
spinal roots and rootlets (before they join to become nerves, which is PNS)
a nerve is what?
a bundle of both efferent and afferent axons
the gray matter of the ___ horns often comes right up to the edge of the spinal cord, whereas the ___ horns often have white matter in between
dorsal; ventral
the spinal cord, unlike the brain, has only one layer of dura. Why?
flexibility
neural crest cells differentiate into _____ cells, which later become what important part of this afferent pathway
somatosensory; dorsal root ganglion
small branches off of nerves are called
rami (sing. ramus)
rami are involved in a variety of functions. Name two
sympathetic chain ganglia activation like sweat gland innervation(ventral), and sensation from back muscles (dorsal)
the central canal is to the spinal cord as the ____ is to the brain
ventricular system . (CSF flows thru central canal)
why is there a dorsal root ganglion but no ventral?
DRG is the cell bodies of somatosensory cells, but the cell bodies for the ventral pathway are in the spinal cord, which go to innervate muscles
which is the only monosynaptic reflex in the body
the patellar tendon (deep tendon) reflex ( knee jerk)
the very end of the spinal cord is called
conus medularis
where are the spinal enlargements and why are they there?
in the cervical and lumbar regions. It is because there is heavy innervation in these regions as these are dermatomes which pass over limbs and limb movement is highly important.
the caudal equina is
the horses tail, after the conus medularis. It is dorsal and ventral roots from sections below L2, which exit thru an intervertebral foramen.
the cauda equina contains which important structure for anchoring the spinal cord in the sacral region to the pelvic bone
the filum terminale
why are shingles often confined to one dermatome
the virus which causes shingles lies dormant in the DRG. When you experience heavy stress, it travels along the axons until it gets to the end and multiplies and bursts, causing the painful rash known as shingles
Anterolateral spinothalamic pathway is involved in which sensation
PAIN, BITCH
the pathway which is invovled in touch/pressure is known as
the dorsal column medial leminscus pathway
detail the dorsal column medial leminscus pathway and how touch/pressure info gets into the brain
1) primary sensory neurons pick up information from receptors, axons bipass dorsal horns and travel medially and upwards ipsilaterally until the
2) medial leminscus of the medulla, where they synapse onto secondary neurons and decussate and travel up to the
3) ventral posterior thalamus, where they synapse onto tertiary neurons which project to S1. This is a CLASSIC trisynaptic pathway
detail the Anterolateral spinothalamicpathway and how pain/temperature info gets into the brain
1) free nerve endings on primary neurons pick up pain info and enter the dorsal horns on small, unmyelinated axons,
2) which immediately decussate within the spinal cord onto secondary neurons, then travel up to the
3) VP thalamus, whose tertiary neurons go to S1 as well.
the fastest conducting axons in our body communicate what kind of info
touch/pressure. pain is quite slow and heavily modulated
a lesion to the left dorsal horn in the midthorassic region would produce
no sensation on the left side of the body from that zone and lower in the spinal cord (sacral, lumbar)
if you damaged the point of pain decussation in S3, what deficits would follow
bilateral lack of pain sensation, but limited to the S3 dermatome
