Flashcards in Lecture 4 Deck (26):
There are 31 pairs of spinal nerves. Break 'em down.
What are the 2 enlargements of the spinal cord?
Cervical (enter upper extremities)
What is the lumbar cistern? Clinical significance?
Subarachnoid space enlargement between L2-S2 (CSF, cauda equina...)
Lumber puncture between L4/5
Where is gray vs white matter in the spinal cord? What is the ventral dorsal situation?
Gray = inside, white = outside
Makes sense! You know the tracts run on the outside of the spinal cord (white matter)
Normal ventral/anterior and dorsal/posterior situation
What is the central landmark on the front and back of the spine?
Anterior median FISSURE
Posterior median SULCUS
(Where blood vessels travel)
How is gray matter divided in the spinal cord?
HORNS: anterior/ventral, intermediate, posterior/dorsal
What are major white matter divisions? What additional structures may you see (2)?
FUNICULI: anterior, lateral
Posterior - gracilis (always) and sometimes cuneatus depending on where you are! Will be separated by posterior intermediate sulcus
There are different ratios of white and gray matter at different spinal segments. Why is this?
Fiber pathways going down and up the spinal column terminating at different levels depending on what they innervate
Ex: S4 gray > white, C3 white > gray
Describe neurons in the DRG.
Ganglion = PNS cell bodies
Bipolar or pseudounipolar neurons (both sensory - into dorsal horn)
Round cell body
1 axon that bifurcates - 1 branch to periphery, 1 to spinal cord
What neurons synapse at the lateral horn? Ventral?
How many laminae are in the spinal cord gray matter? Where are they located?
1-7 = dorsal
- Smaller pain neurons enter into superficial layers
- Medium --> large myelinated neurons for touch and position into deeper layers
8 & 9 = ventral
10 around central canal
Do pain nerves throw collateral branches into fasciculi?
NO - direct to dorsal horn (reflex arch foreshadowing?)
Which 2 information travels via nerves with collateral branches into fasciculi then onto the brain?
Tactile and proprioceptor nerves
What are lamina 1 input and output?
Input = nociception (harmful stimuli)
Output = Contralateral spinothalamic tract
Describe L2 & L3.
Interneurons - connect L1 and deeper laminae
L2 = substantia gelatinosa
What is the nucleus proprious? Function, input and output.
= L3, 4, 5
Input = mechanoreceptive afferents and terminal branches from group 1 muscle afferents
Output = CONTRAlateral spinoTHALAMIC tract
*Cross to the other side!*
What is the difference between 1st, 2nd, 3rd, and 4th order neurons?
1.The first order sensory neurons are in the dorsal root ganglia or the sensory ganglia of cranial nerves.
2. The second order sensory neurons are in the dorsal gray column or various sensory nuclei of the brainstem.
3. The third order sensory neurons are in the thalamic nuclei.
4. Connect different parts of the brain
What are the input and output for L6 & 7?
Input = proprioceptive from Golgi tendons/muscle spindles
Output = Contralateral ventral spinocereBELLAR tract
Where is Clarke's/posterior thoracic nucleus? Inputs and outputs.
Medial base of dorsal horn
Thoracic levels of the spine
Output: Dorsal spinocereBELLAR tract
What are the neurons for L8 & 9?
8: motor interneurons
9: lateral and medial motorneurons
For neurons crossing over, where is the spinalthalamic tract? What senses is this tract for?
Ventral and lateral white matter
Temp, pain, touch
Describe pain pathway.
1st order = into dorsal horn
2nd order = cross to spinothalamic tract in ventral-lateral horn
3rd order = somato-sensory nucleus in the thalamus
4th order = into post-central gyrus
Describe the dorsal column (G&C funiculi) pathway.
1st order = incoming axons throw branches into the dorsal funiculi
2nd order = synapse at medulla
Describe the ventral and dorsal spinocerebellar pathway.
L6 & 7 neurons (proprioceptor info)
Axons to the cerebellum
Describe the cortico-spinal tract.
Lateral and ventral options
Pre-central gyrus, cerebral peduncles, pons, pyramids collect here
Give off axons into ventral horns (motor)