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Neuroanatomy > Spinal cord Descending > Flashcards

Spinal cord Descending Flashcards

1
Q

What is the purpose of having a corticospinal tract (CST)?

What’s another name for the CST?

A
  • Fine dexterity (e.g. piano playing)

- Pyramidal tract

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2
Q

What is the name of the CST 1st neuron, starting rostrally? What about the 2nd?

A
  • Upper motor neuron

- Lower motor neuron

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3
Q

Where does the CST begin, specifically?

A

Brodmann’s area #4, or the pre-central gyrus (motor)

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4
Q

Before reaching the brainstem, where do upper motor neurons find themselves after leaving area #4?

A
  • Internal capsule, then cerebral peduncle
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5
Q

In what part of the brain are the cerebral - peduncles located?
What’s another name for the peduncles?

A
  • Midbrain

- Crus cerebri

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6
Q

Once the fibers of the CST traverse the pons and reach the medulla, what are the fibers traveling in?

A

Pyramids (hence pyramidal tract)

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7
Q

What region of the sc do CST fibers travel in?

A

Lateral funiculus

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8
Q

*At the end of their travel in the lateral funiculus of the sc, where do CST fibers synapse?

A

Anterior horn cells (of the medial and lateral motor nuclei in the ventral horn of the spinal cord)

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9
Q

*Where do fibers of the CST decussate?

A

At the medullary pyraminds, before entering sc

10% don’t cross until the ventral funiculus

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10
Q

Explain the cortical homunculus of the CST.

Where on the cortex are arm cells? Leg/trunk cells?

A

The corticospinal tract is somatotopically organized throughout its entire projection. The cells of origin functionally associated with the arm are located in the lateral convexity of the cortex, whereas the cells of origin functionally associated with the leg are located along the medial wall of the hemisphere. Head is even more lateral.
(devo hint: arms rotate laterally, legs medially)

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11
Q

What is the name of the white mater of the cerebral cortex where these fibers converge (not area #4)

A

Corona radiata

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12
Q

What 2 important nuclei occupy the same space as the these fibers that synapse in the anterior horn, and are found higher up in the cervical cord?

A
  • Phrenic nucleus (C3-C5)

- Spinal accessory nucleus (C1-C6)

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13
Q

Generally, what types of CST info terminates at the dorsal horn?

Intermediate gray?

Ventral horn?

A
  • Modulate sensory afferents
  • From somatosensory cortex
  • Gross, rapid movements
  • Fine movements (independent digit movements and flexors)
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14
Q

What are 2 names for the cells of origin of the CST, originating (mostly) in area #4?

A
  • Pyramidal cells

- Betz cells

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15
Q

In transverse sectioning, what main structures does the internal capsule run b/w, regarding the CST?
What about in coronal section?

A
  • Thalamus and striatum
  • Caudate and lentiform nucleus

*Caudate nucleus and thalamus run medial to it, lentiform nucleus is lateral to it

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16
Q

What’s the name of the area of the midbrain that is immediately dorsal to the cerebral peduncles?

A 
Substantia nigra
(Has nothing to do w/CST)
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17
Q

After leaving the medulla and traveling in the lateral funiculus, what are the names of the axons now called?

A

CST proper

18
Q

*What would be the repercussions of an upper motor neuron lesion?

A
  • Spasticity (m. rigidity)
  • Exaggerated reflexes
  • Hemiplegia (paralysis to 1 side)
19
Q

What cells of the CST would be considered lower motor neurons?

A

Anterior horn cells and their axons

“final common pw”

20
Q

*What would be the repercussions of a lower motor neuron lesion?

A
  • Fasciculations (brief, spontaneous contractions of small groups of m.)
  • Hyporeflexivity
  • Flaccid paralysis
21
Q

Define motor unit.

A

Alpha motor neuron plus the skeletal muscle fibers it innervates

22
Q

Small motor units result in ________ movements, while large motor units result in ________ movements.

A
  • Precise

- Axial/course

23
Q

What part of the CST does ALS affect?

Would lower or upper motor neuron sx dominate?

A

ALS destroys the anterior horn cells and the pyramidal cells.
- Lower motor neuron signs dominate (fasciculations, hyporeflexivity, flaccid paralysis)

24
Q

A CVA in area #4 would affect what cells?

Would lower or upper motor neuron sx dominate?

A

Pyramidal/Betz cells

- Upper motor neuron signs dominate (spasticity, exaggerated reflexes, hemiplegia)

25
Q

How would one test to elicit the Babinski reflex?
What would a normal response be (negative)?
What would an abnormal (or infant) response be (positive)?

A
  • Stroke the sole of the foot
  • Neg: Toes curve inward, foot everts
  • Positive/infant: Hallux dorsiflexes, toes fan out
26
Q

Positive Babinski sign would indicate what specific pathology?

A

Upper motor neuron (CST) damage

27
Q

Which tracts would an anterior spinal artery occlusion wipe out?
Which would be unaffected?

A
  • CST, STT, SCT all wiped out

- DCP retained

28
Q

Subacute combined degeneration is a result of what deficiency?
What tracts would be affected?

A

Vitamin B12

- Would wipe out much of DCP, CST

29
Q

Neurosyphilis primarily affects what tracts/cells?

A

DCP and DRG

30
Q

Thru which part of the crus cerebri of the midbrain does the CST travel?

A

The middle part

31
Q

The nucleus proprius is a part of which tract(s)?

A

STT (“p” for pain)

32
Q

Area 312 is involved in which tracts?

Area 4?

A
  • 312: DCP and STT

- 4: CST

33
Q

Which tract(s) decussate in the sc?

A
  • STT
  • VSCT
  • DSCT (doesn’t really matter, 10%)
34
Q

The medial lemniscus is involved in which tract(s)?

A

DCP

35
Q

The nucleus dorsalis is involved in which tract(s)?

A

DSCT

36
Q

What is the name of the nucleus we have referenced so far in the thalamus?

A

VPL (ventral posterolateral nucleus)

37
Q

Clark’s nucleus is involved in which tract(s)?

A

DSCT

38
Q

The pyramids are involved in which tract(s)?

A

CST

39
Q

Which tract(s) involve decussation in the medulla?

A
  • CST and DCP
40
Q

The medial and lateral motor nuclei are involved in which tract(s)?

A

CST

41
Q

What types of neurons leave the IML (thoracic horn)?

A

Sympathetics

42
Q

Which tract(s) use(s) the inferior cerebellar peduncle (ICP)? What about the SCP?

A
  • DSCT and CCT

- VSCT

Neuroanatomy (20 decks)

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