Week 5 - Spinal cord Flashcards
Where is the spinal cord found?
Enclosed in the vertebral canal
How many spinal nerves per body segment?
One
What is a spinal cord segment?
A slice that gives one pair of spinal nerves
Where is the region that # of nerves differs from vertebrae?
The cervical spine - there are 8 cervical nerves and only 7 vertebrae. This is because the nerve coming out between the skull and the axis is called C1
Is the vertebral column or spinal cord longer?
Vertebral gets longer, though they’re equal orginally
The greater mismatch is at the lower segments
Where does the spinal cord end in adults?
At L1 - average is L1-L2
How do nerves exiting the spien account for vertebral column and spinal cord height difference?
Nerve exits remain fixed, so the lower nerve roots descend as a bunch
Cauda equina - tail
What are meninges?
The covering for the CNS
What is the Dura Mata?
A tough, thick layer that is a tube-like extension in the vertebral canal, for nerves
What is the arachnoid mata?
The spiderweb like, delicate layer within the dura mata. This ends at the lower sacral levels
What is the Pia mata?
Follows the surface of the brain very very closely
What is within the arachnoid?
Subarachnoid space. This contains only nerve roots + CSF below L1
What are the two roots of the spinal nerve?
Dorsal (sensory)
Ventral (Motor)
Each root has multiple rootlets
Where is the dorsal root ganglion?
Nearly the intervertebral foramen
Describe the two primary rami
Both are mixed nerves
One is dorsal
One is ventral
The anterior is much larger than the posterior
What does the dorsal rami supply?
Posterior muscles of the vertebral column + band of overlying skin
What do the thoracic ventral rami do?
These are intercostal nerves
T1 also contributes to brachial plexus
T12 is a subcostal nerve - no rib after rib 12
What do the cervical ventral rami do?
C1-C4 are cervical plexus
C5-C8 are brachial plexus
What do sacral and lumbar ventral rami do?
L2-S3 are the lumbar + sacral plexuses
What are the venterolateral and dorsolateral sulci?
Where the rootlets attach to the spinal cord
Where do you find the grey matter of the spinal cord?
In the middle - looks like an H.
There are ventral and dorsal horns, which reach ut towards their corresponding rootlets
What divides white matter into three regions?
The H-shaped grey matter
What are the three regions of white matter? What are their proper names?
There are three white funiculi:
Dorsal white funiculus, lateral … and ventral …
Is gray matter uniform?
No, there are functionally distinct groups of neuron bodies, with indistinct boundaries
What is in the ventral horn?
Neurons with motor function, arranged in groups
What’s in the dorsal horn?
Neuron bodies with sensory function
Where do you find autonomic neuron bodies?
In the intermediate (lateral) gray horn
What do autonomic neuron bodies do?
Unconscious things
What do you find in the gray matter aside from neuron bodies?
There are a high number of interneurons and glia
Where are neurons for flexors?
These are more dorsal - opposite to body plan
Where are neurons for extensors?
More ventral
Where are neurons for proximal and distal muscles?
Proximal - medial
Distal - lateral
Where are neurons for proximal and distal muscles?
Proximal - medial
Distal - lateral
What are white matter tracts?
These are bundles of functionally similar fibres in the CNS. They’re either ascending or descending and can cross the spinal cord.
There can be overlap between neighbouring tracts
Where is the origin of a white matter tract?
Where the specific neuron bodies are
Where is the termination/destination of a white matter tract?
Where the axons end
Where is the termination/destination of a white matter tract?
Where the axons end
How are most tracts named?
By their origin and termination
AKA - a tract begins in cerebral cortex, terminates at all levels of the spinal cord and is in the lateral white funiculus of the spinal cord.
Therefore, it is the lateral corticospinal tract
