Spinal Cord and Nerves Flashcards
Subdivisions of the nervous system

What is gray matter? What is it called in the CNS/PNS?
A collection of nerve cell bodies.
CNS: Cortex and nucleus
PNS: Ganglion

What is white matter? What is it called in the CNS/PNS?
Axons with glial sheath (myelin).
CNS: pathway e.g. tract/fascicle
PNS: nerve

How many spinal nerves are there?
31 pairs:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
Where do the spinal nerves emerge from the spinal cord?
Intervertebral formaina (space between each vertebrae)
how many spinal vertebrae are there?
- 7 cervical
- 12 thoracic
- 5 lumbar
- Sacrum (5 fused)
- Coccyx (3-4 fused)

- Where does the spinal cord extend from/to?
- How does it terminate?
- What is it continuous with superiorly?
- Extends from: foramen magnum
- Continuous with medulla oblongata superiorly
- Extends to: vertebral levels L1-L2
- Terminates as conus medullaris
What is the conus medullaris?
The tapered, lower end of the spinal cord. It occurs near lumbar vertebral levels 1 (L1) and 2 (L2), occasionally lower.
Cross section of spinal cord
- Spinous process posteriorly
- Vertebral body anteriorly

Dorsal view of spinal cord. What is cauda equina?
The long collection of nerves that leave the spinal cord at the lower end of the spinal cord (i.e. below the conus medullaris)

View of termination of spinal cord as the conus medullaris as well as cauda equina

What is the filum terminale?
- A delicate strand of fibrous tissue proceeding downward from the conus medullaris to insert into the coccyx
- Provides an inferior attachment for spinal cord –> secures it into the coccyx to prevent excessive movement

Describe the meningeal arrangement surrounding the spinal cord
- Dura mater –> only one layer: the meningeal layer
- Dural sac:
- Membranous sheath of dura mater that surrounds the spinal cord and caudal equina
- Contains CSF
- Extends lower than termination of spinal cord –> encompasses cauda equina nerves
- Under dura mater is the arachnoid layer
- Under the arachnoid layer is the subarachnoid space, filled with CSF

What are the cauda equina nerves suspended in?
CSF
What 2 enlargements are found along the spinal cord?
- Cervical enlargement
- Lumbar enlargement

What are the regions of the spinal cord?
Based on spinal nerves: each spinal nerve segment gives rise to 1 pair of segmental spinal nerves.
- 8 Cervical segments (C1-C8)
- 12 Thoracic segments (T1-T12)
- 5 Lumbar segments (L1-L5)
- 5 Sacral segments (S1-S5)
- 1 Coccygeal segment (Co1)
- Conus medullaris
- Cauda equina
- Filum terminale

Are the pairs of spinal nerves part of the CNS or PNS?
PNS
Where does the dural sac extend to?
S1/S2

What is the lumbar cistern? What does it contain?
- Refers to the subarachnoid space in the lower lumbar spinal canal.
- The cistern is an enlargement of the subarachnoid space in the dural sac, distal to the conus medullaris.
- It contains CSF and the nerve roots of the cauda equina.

Why is the cervical spinal region thicker (cervical enlargement)?
- Cervical region is where you find all the motor cell bodies (gray matter) that innervate the upper limbs
- Including collections of nerves that form the brachial plexus (C1-C8)

What is the lumbosacral enlargement?
- A widened area of the spinal cord that gives attachment to the nerves which supply the lower limbs
- Lumbosacral plexus (L1-S4)
- It commences about the level of T11 and ends at L2

What roots does the cauda equina contain?
Dorsal and ventral roots of lower lumbar, sacral and coccygeal spinal nerves

Why is there 7 cervical vertebrae (C1-C7) but 8 cervical nerves (C1-C8)?
C1–C7 emerge above their corresponding vertebrae, while C8 emerges below the C7 vertebra (and just above T1 vertebrae)

how do the cervical spinal nerves emerge in relation to their corresponding cervical vertebrae?
C1–C7 emerge above their corresponding vertebrae, while C8 emerges below the C7 vertebra (and above T1)












































