The anatomy of the sphenoid sinuses is very variable. A single cavity may be present, but a double sphenoid sinus divided by a septum is more common. Such a septum may divide the sphenoid sinus into very asymmetrical cavities. Sometimes the sphenoid sinuses appear as multiseptated cavities.
The degree of pneumatization of the sphenoid bone is also very variable; the sphenoid sinus may exhibit lateral recesses, extending into the greater and lesser wings of the sphenoid bone, and into the pterygoid processes. A bony dehiscence may be present at the level of the internal carotid artery or optic nerve canal (see optic canal bony dehiscence). Also, see sphenoid sinus.
2. Pathology
Inflammation
Inflammatory disease is common in the sphenoid sinus; see sinonasal cavities inflammation, fungal sinusitis.
- mucocele
Mucoceles are uncommon in the sphenoid sinus. They may produce symptoms due to compression of the orbital apices, including the optic nerves.
- sphenochoanal polyp
Trauma
Skull base fractures may include the sphenoid sinus; such a sphenoidal fracture is often an extension of a longitudinal fracture temporal bone. The sphenoid sinus may also become involved in a nasoethmoid fracture or Le Fort III fracture (see facial fractures and Le Fort fractures). Sphenoid fractures are often complicated by post-traumatic cerebrospinal fluid leak.
Tumour
Primary neoplasms of the sphenoid sinus are uncommon. Similar tumours to those arising in other parts of the sinonasal cavities may be encountered (see sinonasal cavities cancer). Angiofibroma commonly grows into the sphenoid sinus. Pituitary neoplasms may also extend into the sphenoid sinus.
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