Afferent pathways I Flashcards
Which nucleus in the thalamus do sensory fibers from the body relay in?
The ventral posterolateral (VPL)
Which nucleus in the thalamus do sensory fibers from the face/head relay in?
The ventral posteromedial (VPM)
What is the pathway for epicritic (general sensation) sensory information from the body?
The dorsal column-medial lemniscal tract.
How does epicritic info from the lower half of the body (T6 and below) travel? (1st order neurons)
It enters in the dorsal root and ascends as the gracile fasciculus.
How does epicritic info from the upper half of the body (T7 and above) travel? (1st order neurons)
It enters in the dorsal root and ascends as the cuneate fasciculus.
What is the path of the gracile and cuneate fasciculi?
They both ascend ispilateral to their respective dorsal root.
Where do the gracile/cuneate fasciculi synapse at?
In the medulla on 2nd order cell bodies in the gracile and cuneate nuclei respectively.
Where do 2nd order neurons in the gracile/cuneate nuclei travel?
They immediately decussate to the contralateral side of the medulla. This decussation is called the internal arcuate fibers.
After decussating, what are the 2nd order neurons from the gracile/cuneate nuclei called?
The medial lemniscus.
What does the medial lemniscus do?
Ascends to the thalamus and synapses in the VPL on cell bodies of 3rd order neurons, which project through the internal capsule to the post-central gyrus.
