Lecture 4: Spinal Cord

Question 1

Number of spinal nerves in each segment?

other associated structes and their level?

Answer 1

8 Cervical

12 Thoracic

5 Lumbar

5 Sacral

1 Coccygeal nerve

Cauda equina begins at L2 and the Filum Terminale anchors the cord to prevent movement.

Question 2

Subdivisions of the Gray matter?

draw this if you’re up for it

Answer 2

I = posteromarginal nucleus

II = substantia gelatinosa

III and IV = nucleus proprius

VII = intermediated zone

• contains the intermediolateral nucleus and dorsal nucleus of clark

VIII = medial motor column

IX = lateral motor column

X = central gray band

Question 3

Pain and temperture pathways?

Answer 3

1. Free nerve ending in periphery and unmyelinated fibre
2. cell body found in dorsal root ganglion
3. Synapses in nucles I (posteromarginal nucleus) or II (substantia gelatinosus).
4. normally info passes across the ventral white commissure to the ventral funiculus to head to the brain.
5. under extreme conditions a withdrawl of polysynaptic reflex occurs with fibres is the IX lateral motor column.

Question 4

Major difference between nuclei I and II

Answer 4

Both are for synaptic junctions of pain and temperature sensation but Substantia Gelatinosus (II) have opoid receptors meaning a cut can be dulled by opoids but a burn not as much.

Question 5

Discriminitive sensation pathway?

Answer 5

1. Myelinated fibres come in with their cell bodies in the Dorsal root gangloin
2. Some fibres head directly to the Dorsal funiculi (cuneate and gracile fasciculi) and head up the spinal cord
3. Some fibres head to nucleus proprius before a fibre heads back to the dorsal funiculi
4. Some fibres head to the dorsal nucleus of Clarke to inform the cerebellum of what’s going on.
5. Others head directly to the lateral motor column to elicit a Myotactic reflex.

Question 6

Organisation of the lateral motor column?

Answer 6

Flexors more dorsal and extensors more ventral

distal more lateral and proximal more medially

Question 7

Explain the final steps of the corticospinal tract for voluntary muscle movement?

Answer 7

1. Info comes down UMN in the Lateral funiculus/motor columns
2. Synapses with a LMN in the lateral motor column (VIII and IX)
3. LMN heads out the ventral root to innnervate muscles.

Question 8

Area between the dorsal root and nuclei I?

Answer 8

Dorsolateral tract of Lissauer

Question 9

Function of area V and VI and VII?

Answer 9

V and VI = Involved with visceral input to/from the inner organs

VII = intermediate zone/horn relates to sympathetic input

Question 10

Trend from top to bottom of spinal cord in relation to white and gray matter amounts?

Answer 10

As you travel down the spinal cord you get an increased ratio of Gray matter compared to White matter.