| Bone: Sphenoidal sinuses | |
|---|---|
| Lateral wall of nasal cavity; the three nasal conchæ have been removed. (Sphenoidal sinus visible at upper right, in dark circle.) | |
| Nose and nasal cavities. (Sphenoid sinus labeled at upper right.) | |
| Latin | sinus sphenoidalis |
| Gray's | subject #223 998 |
| MeSH | Sphenoid+Sinus |
The two sphenoidal sinuses (or sphenoid) contained within the body of the sphenoid vary in size and shape; owing to the lateral displacement of the intervening septum they are rarely symmetrical.
The following are their average measurements: vertical height, 2.2 cm.; transverse breadth, 2 cm.; antero-posterior depth, 2.2 cm.
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When exceptionally large they may extend into the roots of the pterygoid processes or great wings, and may invade the basilar part of the occipital bone.
Each sinus opens into the roof of the nasal cavity via apertures on the posterior wall of the sphenoethmoidal recess directly above the choana. The apertures are located high on the anterior walls of the sinuses themselves.
Because only thin shelves of bone separate the sphenoidal sinuses from the nasal cavities below and hypophyseal fossa above, the pituitary gland can be surgically approached through the roof of the nasal cavities by first passing through the anterioinferior aspect of the sphenoid bone and into the sinuses, followed by entry through the top of the sphenoid bone into the hypophyseal fossa.
If a fast-growing tumor erodes the floor of the sinus, the vidian nerve could be in danger. If the tumor spreads laterally, the cavernous sinus and all its constituent nerves could be in danger.
The mucous membrane receives sensory innervation by the posterior ethmoidal nerves, and postganglionic parasympathetic fibers of the facial nerve that synapsed at the pterygopalatine ganglion which control secretion of mucous.
A potential complication of sphenoid sinusitis is cavernous sinus thrombosis.
They are present as minute cavities at birth, but their main development takes place after puberty.
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
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