Lateral geniculate bodies Flashcards
How is each lateral geniculate body distinguishable on the surface of the brain?
as an ovoid projection on the posteroinferior aspect of the thalamus, partly obscured by the overhanding temporal lobe
What are 4 structures that the lateral geniculate bodies consist of?
- body
- head
- spur
- hilum
What is the hilum of the lateral geniculate nucleus continuous with?
the groove between the medial and lateral root of the optic tract, which enters its anterior aspect
Where does the hilum of the LGN lie?
at the anterior aspect of the pulvinar, which also partly surrounds it, particularly from above
How many cell layes or laminae does the LGN consist of?
6 - numbered 1 to 6 beginning at the hilum
How are the 6 laminae of the LGN arranged?
oriented in a dome-shaped mound similar to a stack of hats
How many cell nuclei are there in the LGN?
approx 1 million
What separates the layers of cell nuclei in the LGN on coronal section?
white matter (optic tract fibres)
Which layers of the LGN do nerve fibes derived from the contralateral eye (crossed fibres from nasal half of retina) terminate on?
layers 1, 4 and 6
Which LGN layers do the fibres from the ipsilateral eye (uncrossed at the chiasm) terminate at?
2, 3 and 5
How many geniculate cells may each retinal ganglion cell axon terminate on?
up to 6 geniculate cells
Are the different cells that 1 retinal ganglion may terminate on located on different laminae?
no, all on 1 lamina
How do the fibres from different parts of the retina terminating in the LGN relate to their position on the retina?
fibres from upper quadrants of peripheral retinae synapse on medial aspect of LGN
fibres from lower quadrant synapse on the lateral aspect
Which part of the retina projects to a disproportionately large part of the LGN and where is this part?
- macula
- disproportionately large central wedge of LGN
What is the shape of the posterior LGN and what is located here?
dome-shaped
from here, geniculate cell axons that form the optic radiation emerge
