What is the purpose of sinuses (to make our skulls lighter?), and why does it have to be connected to our airways?  It seems like they are just infection hazzards.

Good question, Stephanie! As you allude to one popular idea is that the sinuses decrease the relative weight of the front of the skull. Other possible functions include increasing the resonance of your voice, pressure dampening (e.g., from a blow to the face), increasing mechanical rigidity and protecting structures like the eyes from rapid temperature fluctuations in the nasal cavity. The nose is a very effective humidifier and warmer of air and the sinuses contribute to mucosal surface area and perhaps warming ability. Also, the sinuses make mucous like the nose and likely contribute to the immune defense/air filtration performed by the nose. What is really cool is that recent studies suggest that the sinuses are the primary intranasal site for nitrous oxide (NO) formation -  NO is very toxic to microorganisms so maybe the sinuses act as a ‘sterilizer’. It is also claimed that sinus NO formation is increased by humming rather than exhaling silently - see:
http://ajrccm.atsjournals.org/cgi/conte … f_ipsecsha

Hmmmm….

Last edited by Steve Lolait (23rd Sep 2010 10:49:32)

In medical practice we can take advantage of these air-filled bony structures to aid in treatment of pituitary tumours.  The pituitary gland is a pea-sized gland that sits at the base of the brain, directly above the sphenoid sinus.  This is an air-filled cavity in the sphenoid bone located above and behind the nasal cavity.  Therfore, neurosurgeons can operate on the pituitary gland by passing their instruments up the nose and through the hollowed sphenoid bone - clearly this would be much more difficult if the bone was solid, and it provides access to the gland without the need for opening up the skull (craniotomy).

Last edited by David Henley (29th Sep 2010 14:42:29)

I would guess that the intranasal-sinuses route (as distinct from e.g., diffusion or axonal transport along olfactory and/or trigeminal nerves) may also increase the bioavailability of some molecules into the brain due to passage across mucous membranes?

Last edited by Steve Lolait (30th Sep 2010 08:05:06)