5.1 Spinal cord disorders Flashcards
What is in the grey matter of the spinal cord?
- dorsal horns (sensory functions)
- ventral/ anterior horns (motor functions)
- intermediate horns (involved in autonomic functions)
what is in the white matter of the spinal cord?
ascending/ descending tracts –> connects all levels of the spinal cord with the brian
Sensory information flow in from the body at all different levels of the spinal cord through the ___________
- sensory axons travel through the ____________ (contains sensory cell bodies) then continue through the _______ of the ______
- synapse with the ________ which process information and send axons out into the white matter through ___________ to the brain for analysis
- individual becomes aware of the sensation once the information reaches the _____________ of the brain
- motor neurones in the ventral horn send out their axons through the __________ into the spinal nerve and then through the peripheral nerves to control skeletal muscles
spinal nerves
dorsal root ganglion; dorsal root; dorsal horn
interneurones;
ascending pathways;
somatosensory cortex;
ventral roots
What is the function of the lateral corticospinal tract?
Control of voluntary movement of the ipsilateral side of the body (lies distal to the pyramidal decussation in the medulla):
where does the lateral corticospinal tract receive input from?
Receives motor input from the contralateral motor cortex
How are the inputs of the lateral corticospinal tract organized?
Organised somatotopically (cervical most medial; sacral most lateral)
What is the function of the dorsal column (medial lemniscus)
Conveys sensations of fine touch, vibration, proprioception to the thalamus (where it is integrated)
Where does the dorsal column decussates?
Decussates at the sensory decussation (in medulla) then continues as the medial lemniscus pathway to the thalamus (relay centre) then somatosensory cortex
What is the function of the spinothalamic tract?
Conveys sensations of pain, temperature, coarse touch, pressure to the thalamus (where it is integrated):
what does the anterior spinothalamic tract convey?
coarse touch and pressure
what does the lateral spinothalamic tract convey?
pain and temperature
where does the spinothalamic tract decussates?
Decussates at the level of the spinal cord then passes to the thalamus (relay centre) then somatosensory cortex
The meningeal coverings of the spinal cord consist of the 3 layers and separate the spinal cord from the vertebral column. What are the 3 layers (from innermost to outer most)
1) Pia matter (closely adherent to surface of spinal cord)
2) Arachnoid (middle)
3) Dura (dense and tough)
How is the meninges of the spinal cord different from the coverings of the brain
- meninges of spinal cord: presence of the extradural (epidural) space which contains fat and venous plexuses, allowing for the injection of anaesthetic)
- coverings of brain: dura mater is firmly attached to the interior of the cranial cavity
What are the 3 main factors which affect the severity of spinal cord lesions?
loss of neural tissue, vertical level affected and transverse plane
What does the phrenic nucleus (C3-C5) control?
diaphragm (main respiratory muscle)
What does the cervical enlargement (C4-T1) control?
motor neurons controlling muscles of the upper limb?
What does the thoracic region of spinal cord (T1-T12) supply?
thorax and part of upper limb
what does the lumbosacral enlargement (L2- S3) supply?
motor neurones controlling muscles of the lower limb
What does the sacral plexus (S2-S4) supply?
controls bladder and bowel function
What is the presentation of a mid thoracic section of the spinal cord
Paraplegia (paralysis from the waist down) and incontinence (loss of voluntary control of bladder and bowel function):
• Descending motor pathways from the brain cannot reach the lumbar enlargement → cannot stimulate the lower motor neurones in the spinal cord localised there
What is the presentation of a mid cervical section of the spinal cord
Quadriplegia/tetraplegia (no voluntary control over any limbs; paralysis from the neck down) + sensory loss (if complete lesion):
• Occurs above the cervical enlargement → cannot stimulate lower motor neurones supplying the upper and lower limbs
• Ascending pathways are severed if lesion is complete
What is the presentation of a C1/ C2 section of the spinal cord?
Quadriplegia + incontinence + sensory loss + loss of voluntary control of breathing (paralysis of diaphragm → require artificial ventilation):
• Occurs above the level of the phrenic nucleus → stops motor commands coming down from the respiratory centres in the brainstem to the phrenic nucleus
What is the lumbar cistern?
area filled with CSF below the vertebral level of L2 (only neurological structures present are the dorsal and ventral roots)
Why is the spinal cord much shorter than the vertebral column?
Difference is due to the early development of neural tissue in the foetus, while vertebral column continues to grow (in length especially) up till puberty
Damage to the spinal cord is usually partial (complete severing is unusual) → important to know how much is damaged and how much is left intact (especially the white matter).
Which is more serious: damaging the gray matter or the white matter?
- Small amounts of damage to the grey matter (ventral/dorsal horns) may produce a localised effect (weakening of some muscles or sensory loss)
- Not as severe in effect as damage to the white matter (one of the ascending/descending pathways)
[LATERAL CORTICOSPINAL TRACT]
The cell bodies of the upper motor neurones lie in the ________________ and send their axons down into the ________________, through the base of the brain, then into the brainstem:
• Corticobulbar tract: some axons cross the midline (decussates) in the brainstem to stimulate lower motor neurones and control _______________
• Lateral corticospinal tract: 90% of remaining axons continue down and decussate at the pyramidal decussation (in the medulla) to synapse with lower motor neurones at each spinal level on the _____________ side and control ______________
cerebral cortex; ;
internal capsule;
facial muscles;
contralateral;
body muscles (limbs)
what does hemisection of spinal cord at mid thoracic level cause wrt lateral corticospinal tract?
loss of voluntary control of leg movement on the ipsilateral side to the lesion
what does hemisection of spinal cord at the waist level cause wrt dorsal column ?
loss of touch and proprioception in the leg on the ipsilateral side to the lesion?
The information of the spinothalamic tract comes in through the peripheral nerve and axons synapse in the dorsal horn of the spinal cord:
• Axons then cross over the midline (decussation occurs in _____________) and form the spinothalamic tract on the contralateral side
• Information is relayed to the thalamus then to the somatosensory cortex
the spinal cord at the level which the nerve enters
What does hemisection of spinal cord at waist level cause wrt spinothalamic tract
interrupts the spinothalamic tract of the contralateral side –> loss of pain and temperature perception in the leg on the contralateral side
what is the outcome of brown sequard syndrome?
below injury level, motor weakness or paralysis on one side of the body (hemiparaplegia). Loss of sensation on the opposite side (hemianasthesia).
what is the outcome of anterior cord syndrome?
below injury level, motor paralysis and loss of pain and temperature sensation. proprioception (position sense), touch and vibratory sensation preserved
what is the outcome of posterior cord syndrome?
Below injury level, motor function preserved. Loss of sensory function: pressure, stretch and proprioception (position sense)
what is the outcome of central cord syndrome?
results from cervical spinal injury. . greater motor impairment in upper body compared to lower body. variable sensory loss below the level of injury.
