Position & Extension-on the side of the body of sphenoid,-extending from the apex of the petrous temporal bone (behind)to the medial end of the superior orbital fissure (in front).-Each sinus is 2 cm long and 1 cm wide,
* Medially:• Sphenoidal air sinus.• Hypophysis cerebri.* Laterally:• Trigeminal ganglion.• Uncus of the temporal lobe.* Nerves in its lateral wall: (from above downwards)• Oculomotor nerve.• Trochlear nerve.• Ophthalmic division of trigeminal nerve.• Maxillary division of trigeminal nerve.* Structures within its cavity.• Internal carotid artery.• Abducent nerve (on the lateral side of the artery).• -carotid sympathetic plexus• N.B.: The internal carotid artery may rupture inside the cavernous sinus due to fracture base of the skull. This results in a pulsating swelling behind the orbit.
Anteriorly:• Ophthalmic veins (connect it with the facial vein in the face).• Sphenoparietal sinus.Posteriorly:• Superior petrosal sinus (connects it with the transverse sinus).• Inferior petrosal sinus (connects it with the internal jugular vein).Medially:• Anterior and posterior intercavernous sinuses (connect the 2cavernous sinuses together).Superiorly:• Superficial middle cerebral vein (from the lateral surface of the• brain).• Cerebral veins from the inferior surface of the brain.Inferiorly:• Emissary vein through the carotid canal (connects it with the internal jugular vein).• Emissary vein through the foramen ovale (connects it with the pterygoid plexus of veins).
Superior and inferior Ophthalmic veins Plexus of emissary veins through carotid canal to internal jugular vein inferiorPetrosal sinus
Tributaries of Cavernous SinusAnteriorly, Posteriorly, Medially and Superiorly
In fe Ce rio Cerebral vein nt ro th ral Superficial middle Su pe ph e ve th re in Sphenoparietal sinus r io al tin o ro m a f ph ic th ve al in mSu ic pe ve r io in ro ph th Ri al g m veinsIn ht fe ic sinus rio ve Ca in Inferior cerebral ro ve ph rn Superior petrosal th al ou m s ic S Ce ve in inu nt s th ral v e re ein tin o a f Le f In tC In f a te er ior ve rc rn sin ave sin pet ou us rn us r os es ou a l s sS inu s In f er ior sin pet us r os a l veins Sphenoparietal sinus Su pe Inferior cerebral rio Cerebral vein si r p nu et Superficial middle s ros al
s i nu S s n ou r ve Ca htRig us S in s ou e rn av tC Lef Foramen Vesalius Foramen Ovale Foramen Lacerum Pharyngeal Pterygoid Plexus Plexus
8- Inferior Petrosal Sinus s i nu S s n ou r ve Ca ht Rig us S in s ou e rn av tC Lef Foramen Vesalius Foramen Ovale 1- Superior Ophthalmic Vein Foramen Lacerum2- Inferior Ophthalmic Vein3- Sphenoparietal sinus4- Anterior Facial Vein Pharyngeal Pterygoid Plexus Plexus
-The flow of blood in all the tributaries and communications of the cavernous sinus is reversible because they possess no valves.-Spread of infection to the cavernous sinus leads to its thrombosis.-The cavernous sinus communicates with the veins draining the middle area of the face (dangerous area of the face) through 2 routes:1-Superior ophthalmic vein.2-Deep facial vein, pterygoid plexus of veins and emissary vein through the foramen ovale.
If the cavernous sinus is thrombosed what are the important structures that may be affected?? Q. What is the clinical picture of CST ?• A. Clinical features of CST• General features of infection: fever, rigors, malaise, and sever frontal and orbital headache.• Unilateral exophthalmos and tender eye ball• Oedema of the eyelid and chemosis of the conjunctiva (due to obstruction of the superior and inferior ophthalmic veins).• Third, fourth, sixth cranial nerves and ophthalmic and maxillary divisions of the fifth cranial nerve may be affected (paralysis or paresis):• * Clinical picture of oculomotor paralysis: – External ophthalmoplegia: Paralysis of movements of the affected eye (upward, downward and medial). Ptosis: due to paralysis of the levator palpebrae superioris. Slight exophthalmos. – Internal ophthalmoplegia: Dilated fixed pupil with loss of accommodation reflex. (due to paralysis of the sphincter papillae and cilliary muscles).• *Paralysis of abducent nerve: Paralysis of outward movement of the affected eye.( due to paralysis of lateral rectus muscle)• * Paralysis of trochlear nerve: Paralysis of outward and downward movement of the affected eye. (due to paralysis of superior oblique muscle)• * Anesthesia in the distribution of ophthalmic division of the trigeminal nerve, decreased or absent corneal reflex and possibly anesthesia in the maxillary branch distribution.• 5 . Infection can spread to the contralateral cavernous sinus within 24–48 hr of initial presentation. The earliest feature of such spread is affection of the abducent nerve (6 th cranial nerve) on the opposite side (paralysis of outward movement of the affected eye).