I love the sphenoid complex. It’s gorgeous. It looks so much like a tattered but unbroken moth.
Your sphenoidal sinuses are deep within your skull, behind the olfactory bulb and olfactory sensors in the very back of your nose. They sit around the pterygoid wings of the sphenoid bone, and the upper wall of the sinuses is the upper wings of the bone. These wings are the last bone structure before the brain, and though they’re strong, they’re thin and brittle, and can easily be damaged or destroyed by tumorous growths and head injuries.
Serious sinusitis before antibiotics could become deep-seated (it is usually treated before this happens these days), and if there are any cracks in the pterygoid wings, easily invade the brain cavity. Because of this and related reasons, bacterial meningitis and encephalitis (more serious and higher risk of complications) was at one time much more common than viral meningitis around the world, as it still is in developing countries. The mortality rate was about 10-15%, but many times even people with resolved infections ended up with hearing loss, brain damage, and in children, learning disabilities.
That said, the most important things are that the sphenoid complex seats the pituitary gland, provides support for the optic and the olfactory nerves, and a boundary between the open sinuses (prone to infection) and the brain structures. It prevents transmission of bacteria to the brain, and it provides a stable platform for the nerves that allow us to both see and smell the world around us.
What an important and lovely structure.