Lecture 18

Question 1

What is the former magnum and what is its purpose?

Answer 1

The hole in the skull which connects the spinal cord to the brain.

Question 2

Between what levels of the vertebrae column does the spinal cord exist?

Answer 2

Cervical 1 and lumbar 1 (C1-L1).

Question 3

What is the spinal cord surrounded by?

Answer 3

A cavity (meningeal sack) filled with fluid and a layer of fat.

Question 4

What is the tapered cone shaped structure at the end of the spinal cord (L1/L2 region)?

Answer 4

conus medularis.

Question 5

What is the spinal cavity and where is it located?

Answer 5

A spinal cavity exists between the end of the lumbar level and sacral level, where there are no vertebrae located.

Question 6

What is the Filum Terminale and what does it do?

Answer 6

A long section of bone that extends down from the conus medularis all the way to the end of the spinal cavity.

• It anchors the spinal cord

Question 7

Where do the spinal nerves exit and where do they go?

Answer 7

• some spinal nerves exit between the cervical and thoracic levels and go to the arms and thorax.
• The spinal nerves in the L1/2 levels and below, descend down into the spinal cavity and hang there, these nerves go to the legs, pelvis and abdomen.

Question 8

What is the collection of spinal nerves in the spinal cavity called that descend down from the lumbar, sacral, and coccygeal vertebral column levels called?

Answer 8

Cauda equina (horse’s tail).

Question 9

What is the posterior and anterior parts of the vertebrae called?

Answer 9

Anterior = Ventral
Posterior = Dorsal

Question 10

What is the central nervous system of the vertebrae made up of?

Answer 10

Grey matter (cell bodies) + white matter (axons).

Question 11

What is the peripheral nervous system of the vertebrae made up of?

Answer 11

Dorsal root ganglion + spinal nerve.

Question 12

What is the dorsal and ventral sections of white matter called and what do they do?

Answer 12

White matter are axons.
Dorsal white matter - dorsal columns
Ventral white matter - ventral columns

These axons run both up and down from the brain.

Question 13

What is the dorsal and ventral sections of grey matter called?

Answer 13

Grey matter are cell bodies.
Dorsal grey matter - dorsal horn.
Ventral grey matter - ventral horn.

Question 14

Where does the peripheral nervous system start in the vertebrae?

Answer 14

The dorsal and ventral nerve roots.

Question 15

What kind of information does the dorsal side of the vertebra take in and in which direction does it go?

Answer 15

• Sensory information - flowing into the CNS of the vertebrae and up towards the brain (ascending)

Question 16

What kind of information does the ventral side of the vertebra take in and in which direction does it go?

Answer 16

• Motor information - flowing out from the brain to the CNS of the vertebrae and to muscles (descending).

Question 17

Which directions does the posterior, lateral and anterior columns flow?

Answer 17

Posterior (dorsal) columns - flows upwards to the brain (ascending)

Anterior (ventral) columns - flows downwards (descending).

Lateral columns - flows both up and down (ascending and descending).

Question 18

What kind of motor neurons are in the ventral horns and lateral/ventrolateral horns?

Answer 18

Ventral horns - somatic motor neurons.

Lateral/ ventrolateral - autonomic motor neurons.

Question 19

What would happen if there was damage done to the somatic motor neurons in the ventral horns?

Answer 19

Paralysis of muscles supplied by the spinal nerves from this level, on the same side only.

Question 20

What end of the spinal nerve does afferent information (sensory) enter the spinal cord?

Answer 20

The dorsal root.

Question 21

What is the dorsal root ganglion?

Answer 21

Where the cell bodies of sensory neurons are located.

Question 22

What would happen if the dorsal horn (grey matter) was damaged?

Answer 22

Loss of sensation in regions of the body innervated by neurons from this level, on the same side only.

Question 23

Describe the spinal nerve and how to is split into 2 parts.

Answer 23

The spinal nerve is both the ventral and dorsal roots combined.

The ventral nerve root - flow of information out of the CNS.

The dorsal nerve root - flow of information into the CNS.

Question 24

What happens to spinal nerves once they leave the spinal column (CNS)?

Answer 24

They branch off into a dorsal ramus and ventral ramus (plural= rami).

The ventral ramus communicates with the sympathetic chain via two sympathetic rami.

Question 25

Describe the structure of a peripheral nerve.

Answer 25

• Axon
• Myelated / not myelated
• Covered by endoneurium
• A bunch of endoneurium covered axons form a fascicle
• Fascicles are covered by perineurium
• Fascicles are bundled with each other and with blood vessels to form a nerve.
• Nerves are then covered by the epineurium.

Bundles of axons in the CNS are called a tract.