Spinal Cord Flashcards
What gives rise to the cauda equina?
Conus Medularis.
In the brain, the grey matter cortex is on the outside, is the spinal cord the same or different?
In the spinal cord the central area has the grey processing matter.
The rest is white matter, and there is a vast amount
What is the posterior median sulcus?
Halfway point for the spinal cord.
Difference between post. and ventral median sulcus?
Ventral Median Sulcus has a significant rift, whereas the Dorsal is tightly packed
Where do the dorsal roots come in?
The Dorsolateral sulcus.
What are white matter ‘funniculi’?
larges white matter tracts/ropes. Make up ~50% of the spinal cord. There is a ventral, lateral and dorsal funiculus
Dorsal funiculus —>
ventral funiculus —>
lateral funiculus —>
Dorsal funiculus —> sensation
ventral funiculus —> pain + temp
lateral funiculus —> motor
What are the 2 subdivisions of the Dorsal Funiculus
Gracile fasiculus
Cuneate fasiculus
Purpose of the Gracile Funiculus?
Carries all the sensory info from the leg/foot as it comes in from the dorsal root ganglion to a part of the gracile fasiculus.
Brought in froma Psuedo unipolar neuron (unyelinated).
Sensory Info from my toe would go where in the gracile funiculus?
Medial most part, wheres hip would be lateral.
Organised like a homonculus.
The gracile fuciculus is present at ___ levels of the spinal cord. Why?
All levels, as it takes info from the Lower Limbs
The cuneate fusiculus is present at ___ levels of the spinal cord. Why?
As it carries sensory info from the upper limbs, and therefor will not be present further down.
Why does injury your foot hurt more then injuring your knee?
There are more nerves present in the foot (see pg 45)
What’s in grey matter
Dorsal Horn
Ventral Horn
Lateral Horn
What’s in white matter
Columns
tracts
Fasiculi
Funiculi
Cell that can pick up information about pain and temperature come through the ‘Tract of Lissauer’. Where do they synapse
Rexas Lamine
Synapse at Lamina 1 or 2, where the 2nd order neurons then decussate to the ventral funinculus and travel up to the thalamus via the spinothalamic tract
Describe Lamina 1 fibres
Slow Conducting
Un-myelinated
Convey info on pain and temp
Convergence of the spinal cord.
Occurs on lamina 3/4 and allows the huge surface area of the body to be condensed into the spinal cord, means that many fibres that come into the lamina also synapse onto the funniculus —> brain
Lamina 2
- Pain and temp
- Aren’t really affected by anasthetic, except opiod analgesics (as they have opiod receptors)
Lamina 3 + 4
- Convergence of touch and pressure sensory neurons
- Nucleus proprios
- These neurons then still travel to their respective areas of the gracile and cuneate fasiculus
Lamina 5 + 6
Info on noxious visceral stimuli
Lamina 7
All involved in ANS
Centrally: “Dorsal Nucleus of Clark” which is involved in the cerebellum tract and unconscious proprioreception
Lamina 8+9
where Lower motor neurons pass through (from previously synapsing with UMNs in the lateral funinculus) where they then pass out via the ventral root > muscles of the body
Extensors: periphery
Flexors: medially
What type of cells does each lamina have? Remember granule=sensory and pyramidal=motor
L1-4: granule
L5-7: mixed
L8-9: pyramidal
Where does Pain and temp info from L1/2 go?
To the OPPOSING Ventral Funiculus, then up to the brain via the ‘spinothalamic tract’
Where does the info from Lamina 3/4 go?
To the dorsal columns upto the spinal cord on the SAME SIDE
What passes through lamina 8/9 and then where does it go?
UMN from the lateral funiculus (from the motor cortex) come in, synapsing with LMN at 8/9 to travel to the the body via the ventral root
Myotactic Reflex
Happens bc the discriminative ifor from the periphery, instead of going to the gracile/cuneate fasiculi, it comes down to 8/9 and informs them, the flexor/extensor neurons coordinate for movement such as walking.
Brain only informed AFTER
Withdrawal Reflex
Due to pain or heat, also occurs at the spinal segmental level.
Info synapses in 1/2, and then from there another fibre comes down to 8/9, then ANOTHER fibre that comes down through ventral roots.
Theese 3 fibres cause us to pull away before the brain even realises
