h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Thanks WD, a very nice little summary. You just saved me a little revision time, I have finals in 4 months and I need all the help I can get!

I do have one minor problem though, as far as I understood it, CN II doesn't supply the contralateral eye. The actual 'nerve' bit only runs up to the optic chiasm on the appropriate side.

Although the portion supplying the medial half of the retina (ie. the lateral half visual field) then cross to allow the visual cortex to supply the contralateral field, the nerves themselves don't cross over. The rest of it is the chiasm and the optic tracts up to the Lateral Geniculate Nucleus. Same fibres but different anatomical structures. Sorry to spoil the party

Glad to be of help

I know about the temporal nerve fibres vs nasal fibres aspect, but trying to explain that in words rather than a picture is a bit tricky... hence why I left it out - I know it's only half right - only the nasal fibres cross over, temporal fibres don't (hence why a pituitary tumour in acromegaly presents not only with the classic facies and height, but also a temporal hemiamnopia, as only the nasal fibres are affected), but it was too difficult to explain the whole thing without bogging the whole entry down in jargon... and the head twisting aspect of temporal fibres giving nasal images etc...

You weren't spoiling the party at all! It was a valid point to make - and I should have explained it a bit more Thanks for pointing it out


Good luck with your finals - I'm sure you'll do well Let me know how you're getting on

Stay ,
WD

Congrats from the SubEd (I had forgotten about this entry)