Summary Spinal pathways and reflexes

SPINAL PATHWAYS AND REFLEXES:
Ascending spinal pathways:
There are two:
1. Spinothalamic tract: carries signals regarding pain and temperature
2. Dorsal column: regarding touch and vibration

They consist of 3 consecutive neurones:
1. 1st order neurone; receives signal from stimulus (e.g. hand)
2. 2nd order neurone; relays signal to dorsal horn
3. 3rd order neurone; carriers signal to sensory cortex

Spinothalamic pathway
Function Temperature, pain
1st order neuron Travels from the origin of the
2nd order neurone is where
signal to the posterior horn
of the spinal cord crossing over occurs
2nd order neuron From the posterior horn of After
the spinal cord at the level of second
the signal,
Crosses over antero-laterally, order it is
then travels up to the flipped
thalamus
3rd order neuron From the thalamus to the over so left
primary somatosensory affects
cortex
right side.




Dorsal column pathway:

, Dorsal column pathway
Function Fine touch, vibration
1st order Signal travels straight up the
neuron spinal cord to the
gracile/cuneate nucleus in the
medulla oblongata in the
brainstem
2nd order From nucleus in the medulla,
neuron decussates at the medial
lemniscus (crosses sides at
medulla), then travels to the
thalamus
3rd order From the thalamus to the
neuron primary somatosensory cortex