Sphenoid sinus

The sphenoid sinus is one of the four paired paranasal sinuses that is contained within the body of the sphenoid bone. The sphenoid sinuses vary in size and shape, and owing to the lateral displacement of the intervening septum, which may insert on the carotid canal, they are rarely symmetrical. They cannot be palpated during an extraoral examination.[1]

Sphenoid sinus
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.)
Details
Nerveposterior ethmoidal nerves, and orbital branches of the pterygopalatine ganglion
Identifiers
Latinsinus sphenoidalis
MeSHD013101
TAA06.1.03.003
FMA54683
Anatomical terms of bone

The following are their average measurements: vertical height, 2.2 cm.; transverse breadth, 2 cm.; antero-posterior depth, 2.2 cm.

Structure

When exceptionally large the sphenoid sinuses 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.[2]

Development

They are present as very small cavities at birth, and slowly develop with the growth of the skull. Just after puberty the sinuses finish development.[2]

Nerve supply

The mucous membrane receives sensory innervation by the posterior ethmoidal nerves (branch of the ophthalmic nerve), and postganglionic parasympathetic fibers of the facial nerve that synapsed at the pterygopalatine ganglion which controls secretion of mucus.

Clinical significance

If the tumor spreads laterally, the cavernous sinus and all its constituent nerves could be in danger. An endonasal surgical procedure called a sphenoidotomy may be carried out to enlarge the sphenoid sinus, usually in order to drain it.[3]

Use in neurosurgery

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.

References

This article incorporates text in the public domain from page 998 of the 20th edition of Gray's Anatomy (1918)

  1. Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 64
  2. Human Anatomy, Jacob, Elsevier, 2008, page 211
  3. Kozłowski, Z; Mazerant, M; Skóra, W; Dabrowska, K (2008). "[Sphenoidotomy--the treatment of patients with isolated sphenoid sinus diseases]". Otolaryngologia polska = The Polish otolaryngology. 62 (5): 582–6. doi:10.1016/S0030-6657(08)70319-6. PMID 19004262.
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