Cavernous sinus

Middle Cerebral artery (Ref: B.D. Chaurasia, 3rd Ed, Vol lll/Pg 72, 73) Relation of Cavernous sinus:

A.   Structures outside the sinus:

(a)  Superiorly: Optic tract, internal carotid artery, & anterior perforated substance

(b)  Inferiorly: Foramen lacerum & junction of greater wing of sphenoid

(c)  Medially: Hypophysis cerebri & sphenoid sinus

(d)  Laterally: Temporal lobe with uncus

(e)  Anteriorly: Superior orbital fissure & apex of the orbit

(f) Posteriorly: Apex of petrous temporal bone & crus cerebri of midbrain

B. Structures in the lateral wall of sinus:

C. Structures passing through the centre of sinus:

(a)  Internal carotid artery     (b)  Abducens nerve

Deep Middle cerebral veins drain into the basal veins which drain into the Great cerebral veins that terminate in the straight sinus. Deep Middle cerebral veins neither form direct incoming channels nor direct draining channels for the cavernous sinuses.

The anterior continuation of the cavernous sinus, the superior ophthalmic vein, passes through the superior orbital fissure to enter the orbit. Veins of the face communicate with the superior ophthalmic vein. Because of the absence of valves in emissary veins, venous flow may occur in either direction. Cutaneous infections may be carried into the cavernous sinus and result in a cavernous sinus infection which may lead to an infected cavernous sinus thrombosis. The cavernous sinus is located lateral to the pituitary gland and contains portions of cranial nerves III, IV, V1, V2 and VI, and the internal carotid artery.

• Superior ophthalmic vein (a branch from the inferior ophthalmic vein)
• Superficial middle cerebral vein
• Inferior cerebral veins
• Sphenoparietal sinus

• The occipital sinus is at the base of the falx cerebelli in the posterior cranial fossa. It drains into the confluence of sinuses.
• The sigmoid sinus is the anterior continuation of the transverse sinus in the middle cranial fossa. The sigmoid sinus passes through the jugular foramen and drains into the internal jugular vein.
• The superior petrosal sinus is at the apex of the petrous portion of the temporal bone and is a posterior continuation of the cavernous sinus. The superior petrosal sinus connects the cavernous sinus with the sigmoid sinus.

C i.e. Abducent nerve

B i.e. Superior ophthalmic vein

• Foramen Vesalius is an inconstant foramen that gives passage to an emissary vein that connects pterygoid venous plexus with cavernous sinus (vein of vesalius)Q. It is also k/a sphenoidal emissary foramen as its seen in the great wing of sphenoid, medial to foramen ovale, opposite the root of pterygoid process. When present it opens below near scaphoid fossa (in the pterygoid process of sphenoid & gives origin to tensor vali patatini)

A i.e. Cavernous sinus

Dangerous area of face

Dangerous area of face includes upper lip and anteroinferior part of nose including the vestibule. This area freely communicates with the cavernous sinus through a set of valveless veins, anterior facial vein and superior ophthalmic vein. Any infection of this area can thus travel intracranially leading to meningitis and cavernous sinus thrombosis.

Vein draining dangerous area                                                                                                                  

• Through facial veins communicating with ophthalmic veins (both having no valve)
• Through the pterygoid plexus of veins which communicate with facial vein on one hand and the cavernous sinus through emissary vein on the other hand.

Deep connections of the facial vein include:

• A communication between the supraorbital and superior ophthalmic veins.
• Another with the pterygoid plexus through the deep facial vein which passes backwards over the buccinator. The facial vein communicates with the cavernous sinus through these connections. Infections from the face can spread in a retrograde direction and cause thrombosis of the cavernous sinus. This is specially likely to occur in the presence of infection in the upper lip and in the lower part of the nose. This area is, therefore, called the dangerous area of the face.

Ans. Abducent nerve