The Lateral geniculate nucleus, commonly abbreviated as the "LGN", is a brain cortical structure in the thalamus involved in optical function.
It is arranged in 6 layers - 1 through 6. The LGN recieves action potentials from the optic tracts. Layers 1, 4, and 6 recieve signals from the nasal reticular field. Layers 2, 3, and 5 recieve signals from the temporal reticular field. Layers 1 and 2 recieve action potentials from M-type ganglions and layers 2-6 recieve action potentials from P-type ganglions.
The LGN is shaped like an "L", like a bent knee - the source of the adjective "geniculate" in the name of the LGN.