Spinal cord Ascending

Question 1

What’s another name for the dorsal column pathway (DCP)?

Answer 1

Medial lemniscus pathway

Question 2

What 3 types of info are relayed along the dorsal column pw?

What 3 letter abbreviation?

Answer 2

• 2 pt discrimination
• Vibration
• Proprioception (conscious)
  GSA

Question 3

What part of the brain does unconscious proprioception?

Answer 3

Cerebellum

Question 4

What Brodmann’s area is the precentral gyrus (motor)?

Answer 4

4

Question 5

What Brodmann’s area is the postcentral gyrus (sensory)?

Answer 5

3,1,2

Question 6

What exactly are the “dorsal columns” (what’s another name for each of them)?

Answer 6

Fasciculus cuneatus and fasciculus gracilus

Question 7

In the DCP, first-order axons from the upper limb synapses in the ___________________? First-order axons from the lower limb synapses in the ___________________?

Answer 7

• Nucleus cuneatus

- Nucleus gracilus

Question 8

What is the spatial arrangement of nucleus gracilus vs nucleus cuneatus?
In what part of the sc/brain would you find the synapse?

Answer 8

• Both in dorsal funiculus, gracilus is medial (just like lower limbs rotate medially)
• Medulla

Question 9

Do neurons of the DCP decussate?

If so, where?

Answer 9

• Yes

- After synapsing at the nuclei in the medulla

Question 10

After leaving the medulla, what is the tract of neurons of the DCP known as?

Answer 10

Medial lemniscus

Question 11

Where do the second-order axons of the dorsal column pw synapse, specifically?

Answer 11

VPL (ventral posterolateral nucleus) of thalamus

Question 12

What are the names of the fibers that span from the nuclei gracilus/cuneatus to the medial lemniscus (*crosses midline here)?

Answer 12

Internal arcuate fibers

Question 13

Where do 3rd order axons of the dorsal column pw synapse, specifically?

Answer 13

In Brodmann’s area #3,1,2 of the cerebral cortex (post-central gyrus)

Question 14

Why doesn’t the sensory homunculus in area 3,1,2 contain the head?

Answer 14

Head is done by trigeminal n. complex

Question 15

What types of receptors would lead to use of the dorsal column pw?

Answer 15

• Meissner’s corpuscles (2 pt discrim)
• Pacinian corpuscles (vibration)
• Muscle spindles (proprio)
• Golgi tendon organs (proprio)

Question 16

How does neurosyphilis affect the sc?
What is the name of the symptom the pt would show?
What clinical sign would indicate this?

Answer 16

• Destroys the dorsal spinal column and DRGs (dorsal stuff)
• Sensory ataxia
• Positive Romberg’s sign (pt closes eyes w/feet close together, see if they can stand)

Question 17

If the pt does the Romberg test but falls before they even close their eyes, they are showing signs of what symptom?

Answer 17

Cerebellar ataxia

Question 18

What is the name of the main/probably most important pain pw in the body?

Answer 18

Spinothalamic tract/pw (STT)

Question 19

Where does pain, temp, and crude (simple) touch info from the spinothalamic tract come into the sc?
(we only need to know it does pain)

Answer 19

Lateral division of the dorsal root

Question 20

Where do first-order axons of the spinothalamic tract synapse?
Where do they decussate, if they do at all?

Answer 20

• Nucleus proprius (“proper sensory nucleus”) at level nerve enters sc
• Decussate upon entering sc

Question 21

How many sensory inputs does the nucleus proprius receive?
Have many interneurons does it have?
What levels of the sc is it found?
What part of the gray mater is it found?

Answer 21

• Many
• Many
• All levels
• Dorsal horn

Question 22

What are “tract cells”?

Answer 22

Neurons of the nucleus proprius that project contralaterally as the spinothalamic tract

Question 23

Where do tract cells cross the midline?

Where do the axons of the STT then “pile up”?

Answer 23

• Anterior commissure (white matter), upon entering the sc

- Lateral, and part of the anterior, funiculus

Question 24

Originating in the nucleus proprius, where do second-order axons of the STT go on to synapse, specifically?
Where do the 3rd-order axons finally synapse?

Answer 24

• VPL (ventral prosterolateral nucleus) of the thalamus

- Area 3,1,2

Question 25

The aqueduct of Sylvius and superior cerebellar peduncles can be seen together in which part of the brainstem?

Answer 25

Midbrain

Question 26

What is syringomyelia?

Which fibers of the STT are last to be destroyed and why?

Answer 26

• Synrix = “vacule, hole or tube,” forms near central canal of sc. It can grow and eventually transect the cord.
• Sacral fibers of the STT (positioned most laterally, [C > T > L > S])
• Fibers are spared above and below the lesion (usually)

Question 27

Why is the loss in syringomyelia said to be “vested”?

Answer 27

Fibers are spared above and below the lesion (unless it’s bad enough)
- For the STT, only fibers that are entering and decussating at level of lesion are lost.

Question 28

What are the classic signs of a Brown-Sequard Lesion?

Answer 28

• Proprioception lost ipsilaterally below lesion (DCP destroyed)
• Pain/temp lost contralaterally below lesion (STT destroyed)

Question 29

Review: where do neurons of the DCP decussate?

What about neurons of the STT?

Answer 29

• Medulla

- Sc

Question 30

Not being able to feel L side of the body and R side of the face would be caused by what type of CVA?
What arteries would likely be occluded?

Answer 30

• Wallenburg syndrome–right medullar stroke (contralateral side of body and ipsilateral side of face affected)
• Either vertebral a. or PICA

Question 31

What type of info is transmitted in the spinocerebellar tracts (SCTs)?
What types of receptors?

Answer 31

• Unconscious proprioception

- Muscle spindles (and to a lesser extend) Golgi tendon organs

Question 32

Where do neurons of the dorsal spinocerebellar tract (DSCT) first synapse?
What vertebral levels?
What vertebral levels does the cuneocerebellar tract synapse and w/what nucleus?
Where do they decussate?

Answer 32

• Clark’s nucleus (AKA nucleus dorsalis) and Rexxed VII (occur at some point in sc)
• *C8-L2. *C1-C7 done by cuneocerebellar tract (CCT) @ lateral/accessory cuneate nucleus, not really different except higher up
• Neither decussate

Question 33

What part of the sc do first-order axons of SCTs run in?

Answer 33

Lateral funiculus

Question 34

Which have axons that decussate, VSCT, DSCT, both, or neither?

Answer 34

• VSCT axons cross (twice–can’t be assessed clinically)

- DSCT’s don’t

Question 35

What does damage to the dorsal spinocerebellar tract results in?

Answer 35

The loss of nonconscious proprioception and coordination ipsilateral to the lesion.

Question 36

In terms of peduncles, what’s the different b/w the DSCT and CCT vs. the VSCT?

Answer 36

• DSCT is C8-L2, CCT is C1-C7, use inferior cerebellar peduncle
• VSCT uses superior cerebellar peduncle

Question 37

What nucleus does the CCT use instead of Clarke’s nucleus?

Answer 37

Lateral cuneate nucleus

Question 38

Muscle info from upper body reaches the Lateral cuneate nucleus via the __________________.

Answer 38

Fasciculus cuneatus

Question 39

Muscle afferents from below L3 use _________________ (hitch a ride) to reach Clark’s nucleus.

Answer 39

Fasciculus gracilus

Question 40

Define Friedrich’s ataxia.

Answer 40

Sclerosis of the posterior and lateral columns of the spinal cord; characterized by muscular weakness and abnormal gait; occurs in children An autosomal recessive disease, usually of childhood onset, characterized pathologically by degeneration of the spinocerebellar tracts, posterior columns, and to a lesser extent the corticospinal tracts.

Question 41

Prognosis for Friedreich’s ataxia:

Answer 41

Generally, within 15 to 20 years after the appearance of the first symptoms, the person is confined to a wheelchair, and in later stages of the disease, individuals become completely incapacitated. Most people with Friedreich’s ataxia die in early adulthood if there is significant heart disease, the most common cause of death. Some people with less severe symptoms live much longer.