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
red nucleus is red because of ____ and is in which part of the neuraxis?
iron; mesencephalon
explain the ruberocorticospinal pathway
1) m1 neurons come together make synapses in
2) red nucleus, along with cerebellar inputs which descend and decussates in
3) meduallry-pontine region, which
4) make synapses in ventral horns to control distal limb movements (gross motor control, but not the fine fractionated movements. You ain’t playing piano with this pathway)
fractionated movements are controlled by which pathway
dorsolateral corticospinal tract
what is syringomyelia and how do you get it?
An enlargement/cyst that starts in the central canal of the spinal cord, which represents the loss of tissue. Whiplash often can cause this, as well as bacterial infection. Enlargement can grow and cause pressure-related damage and pain
feeding, walking, posture are all controlled by what pathway?
ventromedial pathway
what differentiates the ventromedial pathway from the corticospinal pathways?
no decussation, instead bifrucation. This is because this pathway controls the trunk, which cannot operate its two sides independently.
What is the function of the following structures in movement:
vestibular nuclei
superior colliculus
reticular formation
1) vestibular nuclei :balance and posture
2) superior colliculus: head movements related to visual information
3) reticular formation : control of coordinated movements like walking
what is stocking and glove syndrome and why does it preferentially affect feet and hands?
it is a weakness in the hands/feet due to the presence of a metabolic toxin. because these limbs are the most distal and have the longest axons, they are the most metabolically costly and so are the first to experience fatigue.
the nucleus of clark is located where and does what?
projects to cerebellum ipsilaterally, located lateral to gray commisure in thorracic
the cervical section of the spinal cord is the only section where __ is visible
gracile/cuneate (separated by median septum) . All other sections just have posterior funiculi
the sacral region is the only section of the spinal cord where the ____ is visible
cauda equina
syringomyelia is caused by ____ and is characterized by what symptoms?
an enlargement to the central canal (usually in the cervical region), loss of touch/pain sensation as the crossing is damaged in the uppermost region. Paralysis at and below the lesion as well
Brown-Sequard syndrome is…?
when half the spinal cord is damaged. Loss of pain in that area and loss of ipsilateral touch to the damage
dorsal column syndrome is caused by..?
damage to dorsal columns (sometimes via syphilis) loss of touch pressure info
what is Friedrich’s ataxia?
an inherited, slow degeneration of the dorsal columns as well as spinal input to the cerebellum