Spinal Chord Flashcards
Tracts Clinical correlates
What 2 types of multipolar neurons found in gray matter of spinal cord?
Golgi type 1
Golgi type 2
Distinguish golgi type 1 and golgi type 2 neurons.
Golgi type 1 - long axons, found mostly in anterior gray horns, form long tracts of spinal cord
Golgi type 2 - short axons, found mostly in posterior gray horns
Which nuclei of the posterior gray horn are found in all spinal cord segments?
Marginal nucleus
Substantia Gelatinosa of Rolando
Chief sensory nucleus/ Nucleus proprius
The dorsal nucleus of Clarke is found in which spinal segments?
C8 - L3
The intermediolateral nucleus are found in which spinal segments?
T1-L2
Name the nuclei found in the anterior gray horn.
Anterior motor neurons
Gamma motor neurons
Renshaw cells
State the neuron in the anterior gray horn that goes to the 1) Intrafusal muscle fibers 2) Extrafusal muscle fibers
*MNEMONIC: AEGI
Anterior motor neurons –> Extrafusal
Gamma motor neurons –> Infrafusal
Role of Renshaw cells
Inhibitory neurons
Differentiate association tracts from commissural tracts.
Association tracts (intrinsic tracts) connect different segments of the spinal cord that are adjacent. Commissural tracts connect same segment but opposite halves
Second order neurons form ascending tracts except in which part of the spinal cord?
The posterior white funiculus which is formed by 1st order neurons (for dorsal lemniscal pathway)
Location of 3rd order neurons
subcortical areas of brain
The 3 stages following complete transection of spinal cord.
- Shock/Flaccidity
- Reflex activity
- Reflex failure
How long does the spinal shock stage last in humans?
3 weeks
Paraplegia is…
paralysis of lower limbs
Events of the stage of spinal shock/flaccidity.
Muscles become flaccid
Paralysis of all limbs (quadriplegia) or lower limbs (paraplegia)
Decrease in heart rate to become thready
Paralysis of respiratory muscles = arrest of breathing
Complete sensory loss in parts below level of damage due to damage to posterior root ganglia
Effect on blood pressure depends on if lesion is below L2 or at/above T1
Which tracts carry pain and temperature?
Fasciculus dorsolateralis
Lateral spinothalamic tract
Which tract carries subconscious kinesthetic sensation? Which one carries conscious kinesthetic sensation?
Subconscious kinesthetic sensation - Lateral and ventral spinocerebellar tracts
Conscious - Dorsal Column
Differences between Reflex activity stage of Complete transection and Incomplete transection
Complete transection
- tone returns to flexors first (paraplegia in flexion)
- reflexes return to flexors first
- Babinski reflex first to return
- mass reflex occurs
Incomplete transection
- tone returns to flexors first (paraplegia in extension)
- reflexes return to extors first (Elicit Philipson reflex)
- no mass reflex
What is Mass reflex
when skin of lower limbs or lower abdominal wall is scratched and ellicits spasms of lower limb flexors, sweating, and urination
Describe Philipson reflex and give another name for it
Clasp-knife reflex in which limb offers resistance to flexion, but when forced to flex, the resistance is abolished immediately and the limb suddenly flexes
Events of Reflex failure stage following spinal cord transection.
- Mass reflex abolished
- Harder to ellicit reflex; reflex requires higher threshold stimuli
- Muscle atrophy
Differentiate Brown-sequard syndrome from incomplete transection.
In brown-sequard, the entire one half of the spinal cord is affected/lesioned. But in incomplete transection, a section of spinal cord is lesioned at one point.
Effects on the same side as the lesion, below level of lesion in Spinal cord hemisection (Brown sequard syndrome) .
Sensory changes on the same side; loss of
-fine touch/tactile
-vibration
-2-point discrimination
-conscious kinesthetic sensation
(uncrossed fibers of dorsal column pathway in spinal cord)
-pain and temperature (from uncrossed fasciculus dorsolateralis tract)
Motor changes
- hypertonicity (UMN no longer inhibiting motor neurons making them hyperactive)
- spasticitiy
- deep reflexes exaggerated, superficial reflexes lost
- +ve Babinski
- decrease in blood pressure
Which spinal cord segments are mostly affected by Syringomelia?
Lower cervical
Upper thoracic
Describe symptoms of Syringomelia if it
a) remains around central canal
b) extends to posterior gray horn
c) extends to anterior gray horn
d) extends to white matter
It if remains around central canal
-loss of temperature, pain, and crude touch because fibers decussating across anterior gray commissure are affected
If extends to posterior gray horn (loss of all sensation since this is where all the sensory nuclei are )
If extends to anterior gray horn (flaccid paralysis because some motor fibers decussate across)
If it extends to white matter (symptoms similar to UMN lesions; spastic paralysis, winging of scapula, scoliosis)
