spinal cord

Question 1

The word dermatome comes from two Latin words which mean what?

Answer 1

Derma = skin; tome=slice

Question 2

the intervertebral foramen is what?

Answer 2

a hole which nerves emerge from the bony protection of the spinal cord; the start of the PNS

Question 3

the central canal (CNS) contains what?

Answer 3

spinal roots and rootlets (before they join to become nerves, which is PNS)

Question 4

a nerve is what?

Answer 4

a bundle of both efferent and afferent axons

Question 5

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

Answer 5

dorsal; ventral

Question 6

the spinal cord, unlike the brain, has only one layer of dura. Why?

Answer 6

flexibility

Question 7

neural crest cells differentiate into _____ cells, which later become what important part of this afferent pathway

Answer 7

somatosensory; dorsal root ganglion

Question 8

small branches off of nerves are called

Answer 8

rami (sing. ramus)

Question 9

rami are involved in a variety of functions. Name two

Answer 9

sympathetic chain ganglia activation like sweat gland innervation(ventral), and sensation from back muscles (dorsal)

Question 10

the central canal is to the spinal cord as the ____ is to the brain

Answer 10

ventricular system . (CSF flows thru central canal)

Question 11

why is there a dorsal root ganglion but no ventral?

Answer 11

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

Question 12

which is the only monosynaptic reflex in the body

Answer 12

the patellar tendon (deep tendon) reflex ( knee jerk)

Question 13

the very end of the spinal cord is called

Answer 13

conus medularis

Question 14

where are the spinal enlargements and why are they there?

Answer 14

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.

Question 15

the caudal equina is

Answer 15

the horses tail, after the conus medularis. It is dorsal and ventral roots from sections below L2, which exit thru an intervertebral foramen.

Question 16

the cauda equina contains which important structure for anchoring the spinal cord in the sacral region to the pelvic bone

Answer 16

the filum terminale

Question 17

why are shingles often confined to one dermatome

Answer 17

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

Question 18

Anterolateral spinothalamic pathway is involved in which sensation

Answer 18

PAIN, BITCH

Question 19

the pathway which is invovled in touch/pressure is known as

Answer 19

the dorsal column medial leminscus pathway

Question 20

detail the dorsal column medial leminscus pathway and how touch/pressure info gets into the brain

Answer 20

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

Question 21

detail the Anterolateral spinothalamicpathway and how pain/temperature info gets into the brain

Answer 21

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.

Question 22

the fastest conducting axons in our body communicate what kind of info

Answer 22

touch/pressure. pain is quite slow and heavily modulated

Question 23

a lesion to the left dorsal horn in the midthorassic region would produce

Answer 23

no sensation on the left side of the body from that zone and lower in the spinal cord (sacral, lumbar)

Question 24

if you damaged the point of pain decussation in S3, what deficits would follow

Answer 24

bilateral lack of pain sensation, but limited to the S3 dermatome

Question 25

red nucleus is red because of ____ and is in which part of the neuraxis?

Answer 25

iron; mesencephalon

Question 26

explain the ruberocorticospinal pathway

Answer 26

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)

Question 27

fractionated movements are controlled by which pathway

Answer 27

dorsolateral corticospinal tract

Question 28

what is syringomyelia and how do you get it?

Answer 28

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

Question 29

feeding, walking, posture are all controlled by what pathway?

Answer 29

ventromedial pathway

Question 30

what differentiates the ventromedial pathway from the corticospinal pathways?

Answer 30

no decussation, instead bifrucation. This is because this pathway controls the trunk, which cannot operate its two sides independently.

Question 31

What is the function of the following structures in movement:
vestibular nuclei
superior colliculus
reticular formation

Answer 31

1) vestibular nuclei :balance and posture
2) superior colliculus: head movements related to visual information
3) reticular formation : control of coordinated movements like walking

Question 32

what is stocking and glove syndrome and why does it preferentially affect feet and hands?

Answer 32

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.

Question 33

the nucleus of clark is located where and does what?

Answer 33

projects to cerebellum ipsilaterally, located lateral to gray commisure in thorracic

Question 34

the cervical section of the spinal cord is the only section where __ is visible

Answer 34

gracile/cuneate (separated by median septum) . All other sections just have posterior funiculi

Question 35

the sacral region is the only section of the spinal cord where the ____ is visible

Answer 35

cauda equina

Question 36

syringomyelia is caused by ____ and is characterized by what symptoms?

Answer 36

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

Question 37

Brown-Sequard syndrome is…?

Answer 37

when half the spinal cord is damaged. Loss of pain in that area and loss of ipsilateral touch to the damage

Question 38

dorsal column syndrome is caused by..?

Answer 38

damage to dorsal columns (sometimes via syphilis) loss of touch pressure info

Question 39

what is Friedrich’s ataxia?

Answer 39

an inherited, slow degeneration of the dorsal columns as well as spinal input to the cerebellum