Cavernous sinus

The cavernous sinus (CS) is one of the paired dural venous sinuses. 

Gross anatomy

The cavernous sinus is located on either side of the pituitary fossa and body of the sphenoid bone between the endosteal and meningeal layers of the dura. The normal lateral wall should be either straight or concave. 

Boundaries

• roof: fold of dura mater attached to the anterior and middle clinoid processes
• anterior wall: medial end of the superior orbital fissure
• posterior wall: petrous apex
• medial wall: endosteum overlying the body of the sphenoid bone
• lateral wall: dura mater from the ridge of the roof to the floor of the middle cranial fossa
• floor: endosteum overlying the base of the greater wing of the sphenoid bone

Relations

• superiorly: middle cerebral artery, optic chiasm
• anteriorly: apex of the orbit
• posteriorly: cerebral peduncle
• medially: pituitary fossa, pituitary gland
• laterally: temporal lobe (medial surface), Meckel's cave (posterioinferiorly)
• inferiorly: sphenoid sinus

Vascular connections

It receives venous blood from:

• inferior and superior ophthalmic veins
• intercavernous sinus
• sphenoparietal sinus
• superficial middle cerebral vein
• occasionally
  • central retinal vein
  • a frontal tributary of the middle meningeal vein

Drainage of the cavernous sinus is via:

• superior petrosal sinus to the transverse sinus
• inferior petrosal sinus directly to the jugular bulb
• venous plexus on the internal carotid artery (ICA) to the clival (basilar) venous plexuses
• emissary veins passing through the
  • sphenoidal foramen
  • foramen ovale: communicates between the CS and pterygoid plexuses
  • foramen lacerum

Depending on relative pressures the superior ophthalmic veins either drain to or from the cavernous sinus.

Additionally, the cavernous sinuses connect to each other via the intercavernous sinuses.

Contents

Nerves

The cavernous sinus transmits multiple cranial nerves to the superior orbital fissure and foramen rotundum. These are:

• in the lateral wall from superior to inferior
  • oculomotor nerve (CN III)
  • trochlear nerve (CN IV)
  • trigeminal nerve (CN V): ophthalmic and maxillary divisions
• traversing the sinus
  • C4 segment of ICA
  • abducens nerve (CN VI): inferolateral to the ICA

These can be remembered with the mnemonic OTOM CAT.

Artery

The ICA enters the posterior inferior aspect of the sinus and bends upon itself as the carotid siphon (cavernous segment - C4). Two branches arise from this segment: meningohypophyseal trunk and inferolateral trunk.

The artery is surrounded by a plexus of sympathetic nerves from the superior cervical ganglion.

Fat

Fatty deposits may be present within the cavernous sinus, especially in obese patients or in those who are taking corticosteroids ³.

Related pathology

• cavernous sinus thrombosis
• caroticocavernous fistula
• cavernous sinus mass