a) ascending pathways
b) descending pathways
are found in the spinal cord?
Important ones (for me anyway) are:
a) DC/ML pathway (fine touch, proprioception, vibration), Spinothalamic tract (firm touch, temperature, pain)
b) Corticospinal tracts (voluntary movement)
Which two tracts does the corticospinal tract split into?
Anterior corticospinal tract (15% of fibres, cross at spinal cord level of muscle)
Lateral corticospinal tract (85% of fibres, have already crossed over at medulla)
Which structures are connected by the upper motor neurons of the corticospinal tract?
Motor cortex TO Anterior horn of spinal cord
Which structures are connected by the lower motor neurons of the corticospinal tract?
Anterior horn of spinal cord TO Skeletal muscle
Where do 85% of corticospinal tract fibres decussate?
Pyramids of the medulla
Compare muscle tone in UMN versus LMN problems.
UMN - hypertonia
LMN - hypotonia
Does atrophy tend to occur in UMN or LMN problems?
muscle can't contract, so atrophies due to underuse
In which type of motor neuron pathology are fasciculations seen?
Describe reflexes in
b) LMN problems.
b) Slow / absent
In which type of motor neuron problem do you see the Babinski reflex?
What does this look like?
When plantar surface of the foot is stroked, toes extend and fan out (abnormal, they should flex)
Describe upper motor neuron disease in terms of
d) muscle tone?
In UMN disease:
a) brisk reflexes
b) little / no atrophy
c) no fasciculations
d) increased muscle tone
Describe lower motor neuron disease in terms of
d) muscle tone?
In LMN disease:
a) Slow / absent reflexes
b) Marked atrophy
c) Fasciculations present
d) Decreased muscle tone
Which sensations are carried by the spinothalamic tract?
Where does the spinothalamic tract decussate?
Where does the DC/ML pathway decussate?
What can happen to the spinal cord to cause disease?
What are some acute causes of spinal cord compression?
Haemorrhage into cord / subarachnoid space
What are some chronic causes of spinal cord compression?
Spondylosis - degenerative spinal diseases
Arthritis (especially RA)
Why is it important to know where the motor and sensory pathways cross over in terms of spinal cord injuries?
If you know where the tract is in the spinal cord
i.e DC/ML pathway and corticospinal tracts will be ipsilateral, spinothalamic tract will already have crossed to be contralateral
You can predict what will be affected by spinal cord injuries
Which pathways are affected by a cord transection?
All of them
Sensory and motor symptoms
Sensory AND motor innervations are totally disrupted bilaterally, below the lesion by which type of spinal cord injury?
Complete cord transection
What occurs acutely below the level of a spinal cord injury?
Describe spinal shock.
Loss of reflexes below the level of an acute spinal cord injury
can occur in injuries like cord transection
Spinal shock is a loss of ___ below the level of a spinal cord injury.
Is it permanent?
What type of spinal injury causes Brown-Sequard syndrome?
Spinal cord hemisection
Damage to one side of the spinal cord
Think about where the crossing over of the DC/ML, spinothalamic and corticospinal tracts occur.
If a patient suffers a cord hemisection, what symptoms will they have and what side will each symptom be felt on relative to the lesion?
IPSILATERAL loss of fine touch, proprioception and vibration (DC/ML runs ipsilateral to skin it supplies and decussates at medulla)
CONTRALATERAL loss of firm touch, temperature and pain (spinothalamic tract decussates at spinal level and runs contralaterally to skin it supplies, upwards)
IPSILATERAL loss of motor function (corticospinal tracts decussate at medulla and run down the spinal cord, ipsilateral to the muscles they control)
What type of injury causes central cord syndrome?
Which pathway is primarily affected by central cord syndrome?
Firm touch, temperature, pain
What sort of distribution does sensory disturbance often have in patients with central cord syndrome?
Which tract is involved, and which senses are lost?
Spinothalamic tract (firm touch, temperature, pain)
What is the difference between the clinical presentation of acute and chronic cord compression?
Chronic is the same but also has UMN signs (increased tone, hyperreflexia, upgoing plantars, clonus)