Neuro 2: Spinal Cord function and Dysfunction Flashcards
How many spinal segments are there?
31
What does the 31 pairs of spinal nerves consist of?
\_\_\_ cervical \_\_\_ thoracic \_\_\_ lumbar \_\_\_ sacral \_\_\_ coccygeal
What does the 31 pairs of spinal nerves consist of?
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
Nerves leave the vertebral column through the _______ ______
Nerves leave the vertebral column through the INTERVERTEBRAL FORAMINA
Where are the 2 enlargements for the innervation of the limbs?
Cervical (C3-T1)
- has extra motor neurones that goes to muscles of the upper limb
Lumbar (L1-S3)
- has extra motor neurones that goes to the muscles of the lower limb
Lesion of nerve above C3-C5 would result in
Lesion of nerve above C3-C5 would result in :
- not being able to breathe
What is a major difference in the development of the spinal cord and the vertebral column?
- spinal cord stops growing early
- vertebral column keep on growing into adulthood.
What part can be used to sample CSF ?
- the lumbar cistern
What are the 3 layers of meninges?
What are the 3 layers of meninges?
- subarachnoid space
- pia mater (denticulate ligaments)
- extradural/epidural space
What is in the subarachnoid space?
CSF
What is the function of the denticulate ligaments?
- tethers the spinal cord
- holds it in the middle of the subarachnoid space
Where is extradural/epidural space located in?
would you find this in the cranial meninges?
- between outside of the dura + the bone
no.
What is epidural space fulled with ?
venous plexuses + fatty tissue
why is the epidural space clinically useful?
clinically useful:
because you can inject anesthetic by giving an epidural
What are the 3 most important tracts in spinal cord injury?
- Lateral Corticospinal Tract
- motor
- for fine movements - Dorsal Columns
- sensory
- touch, vibration, pressure - Spinothalamamic Tract
- pain, temp
What are the 2 stages of response to an injury to the lateral corticospinal tract?
STAGE 1 - spinal shock:
STAGE 2 - Return of reflexes:
Describe stage 1 response to injury to the lateral corticospinal tract
STAGE 1 - spinal shock: - lose all reflex activity below level of lesion - no direct damage (just stops working) - leads to flaccid paralysis (limbs = floppy, little muscle tone)
Describe stage 2 response to injury to the lateral corticospinal tract
STAGE 2 - Return of reflexes:
- hyperreflexia
(if you test knee jerk reflex, legs will go mad)
- spasticity occurs
(spontaneous muscle contraction occurs)
- there is very high muscle tone –> rigid paralysis
most probably due to lower motor neurons below level of lesion being cut off from their normal activating pathway
- -> so they have lowered threshold
- -> becomes more sensitive.
Lateral corticospinal tract neurones decussate at level of ______
Lateral corticospinal tract neurones decussate at level of the medulla
Unilateral lesion in mid thoracic region –> deficit is on same/opposite side as lesion
Unilateral lesion in mid thoracic region –> deficit is on same side as lesion
What is the Dorsal Column responsible for?
Dorsal Column responsible for:
- fine touch + proprioception
Describe the tract/organisation of the dorsal column
- sensory neurons enter the spinal cord
- they travel up same side of spinal cord
- also decussates at level of the medulla
- then goes to the somatosensory cortex
What is the Spinothalamic tract responsible for?
- pain and temperature
Describe the tract/organisation of the spinothalamic tract
- pain nerves cross over immediately as they enter spinal cord
- neurons goes into dorsal horn
- synapses with 2nd cell
- which sends its axon immediately across the midline
Left sided unilateral lesion at mid thoracic level doesn’t interrupt the spinothalamic tract from the ____leg
BUT
it will interrupt the spinothalamic tract going up the ____ side coming from the ___ leg
So lesion on the left causes loss of pain sensation in the ____ leg
Left sided unilateral lesion at mid thoracic level doesn’t interrupt the spinothalamic tract from the LEFT leg
BUT
it will interrupt the spinothalamic tract going up the LEFT side coming from the RIGHT leg
So lesion on the left causes loss of pain sensation in the RIGHT leg
List 3 factors affecting severity of spinal lesion
- loss of neural tissue
- vertical level
- transverse plane
Explain how loss of neural tissue affects severity of spinal lesion
usually trauma –> loss of neural tissue = small
metasases, degenerative diseases –> more extensive loss
Describe how vertical level affects severity of spinal lesion
higher the lesion, greater the disability
What is the most common cause of spinal cord injury?
- broken neck or back
What are the 3 tracts important for spinal cord injury?
- lateral corticospinal tract
- dorsal columns
- spnothalamic tract
Describe the Brown-Seuard syndrome
- with unilateral lesions, the relationship of the deficit to the lesion depends on where the tract decussates.
note:
at top vertebral level +spinal cord segment = correlates
at bottom there is greater discrepancy btw spinal + vertebral levels
–> place where spinal nerve emerges becomes more and more inferior in relation to the vertebral level
-
collection of nerves at bottom =
chordae equina
there are _ cervical vertebrae but ___ cervial nerves
there are 7 cervical vertebrae but 8 cervial nerves
note: there is no epidural space in the brain, but there is a epidural space in the spinal cord
-
why are the presence of meninges important?
- for reabsorption of CSF
- for protection
What is the difference between dermatome / myotomes?
area of skin(dermatome) or muscle (Myotome) innervated by one single spinal nerve/ segment
note: motor neurones goes into ventral horn - (anterior horn) (upper butterfly wing)
sensory neurons goes into dorsal horn (posterior horn) (lower butterfly wing)
but in the RAMUS of both - there is a mixture of sensory + motor
-
Describe the pathway of the corticospinal tract
- voluntary movement starts in motor cortex
- there is a single neurone in the brain which synapses onto the a single neurone in the ventral horn then a peripheral nerve goes out to a muscle
- upper motor neurone = in brain - it emerges and crosses over in the medulla at the decussation of the pyramids –> and travels down the spinal cord –> becomes a part of peripheral nerve –> then goes to a muscle
3 main sensory neurones located at:
- in skin
- in cns
- one going up to the brain
sensory neurone has cell body in the ____ ___ ______
dorsal root ganglion
What does the dorsal column pathway do?
it bring in information about fine touch
–> activates dorsal column
- sensory neurone strive up same side of spinal cord as the part of the body innervated
