Ascending Pathways: Anterolateral System/Spinothalamic Tract

00:00 Another ascending pathway is the anterolateral system. You can consider this to be the spinothalamic tract.

00:12 Again, the prefix spine tells you the starting point and then the thalamus informs you of the destination of this system. It does continue further ascent into the primary somatosensory cortex of the cerebrum.

00:29 This is responsible for conveying crude touch, for example. In this system, we have anterior spinothalamic tract located in through here. This is the part of the system that’s conveying crude touch. There’s also a lateral spinothalamic tract shown in through here. That is conveying pain and temperature to the primary somatosensory cortex. Anterior spinothalamic is crude touch. Lateral spinothalamic is pain and temperature.

01:12 Anterior and lateral comprise the anterolateral system. As mentioned earlier, Lissauer’s tract is the area that your first order neurons enter the spinal cord and will ascend one or two levels then before entering the spinothalamic tract. Here’s the pathway that will follow. The first order neuron is coming in to the spinal cord.

01:46 In this case, it’s coming in to the right side of the spinal cord. It’s going to ascend or even descend one or two levels within this Lissauer's tract before synapsing within the dorsal gray horn. Second order neurons then will immediately cross over where that synapse occurs. We see that occurring at this level. You see the ascension then of the second order neuron in the contralateral spinothalamic tract. Next, the second order neuron will synapse in the ventral posterolateral nucleus of the thalamus with the third order neuron. That location is seen right in through here. Here is the synapse of the second order neuron with the third order neuron. The third order neuron then will continue its ascension and then it will end in the contralateral primary somatosensory cortex.