INTRODUCTION
• The cavernous sinus (2 cm long, 1 cm wide) is a large venous space.
Its interior is divided into a number of small spaces (caverns) by
trabeculae, hence the name cavernous sinus
LOCATION:
• situated on either side of the body of the sphenoid and Sella turcica
in the middle cranial fossa.
BOUNDARIES:
• FLOOR: endosteal layer
• Lateral wall, roof, and medial wall: meningeal layer.
• MEDIALLY: roof is continuous with the diaphragm sellae
• POSTERIORLY: roof has a triangular depression between the
attached margin (edge) of tentorium cerebelli to the posterior
clinoid process and ridge raised by the free margin (edge) of
tentorium cerebelli as it extends forward to gain attachment on the
anterior clinoid process.
• The oculomotor and trochlear nerves pierce this triangle to enter
the cavernous sinus.
EXTENT:
• ANTERIORLY: up to the medial end of superior orbital fissure
• POSTERIORLY: up to apex to the petrous temporal bone.
RELATIONS
SUPERIOR:
1. Optic chiasma
2. Optic tract
3. Internal carotid artery
4. Anterior perforated substance
INFERIOR
1. Foramen lacerum
2. Junction of the body and the greater wing of the sphenoid
MEDIAL
1. Pituitary gland (hypophysis cerebri)
2. Sphenoid air sinus.
LATERAL
1. Temporal lobe (uncus) of the cerebral hemisphere.
2. Cavum trigeminale containing the trigeminal ganglion.
ANTERIOR
1. Superior orbital fissure.
2. Apex of the orbit.
POSTERIOR
1. Crus cerebri of midbrain.
2. Apex of the petrous temporal bone.
STRUCTURES PRESENT IN THE LATERAL WALL OF THE SINUS
FROM ABOVE DOWNWARD:
1. Oculomotor nerve.
2. Trochlear nerve.
3. Ophthalmic nerve.
4. Maxillary nerve.
STRUCTURES PASSING THROUGH CAVERNOUS SINUS:
1. INTERNAL CAROTID ARTERY surrounded by the sympathetic
plexus of nerves.
2. ABDUCENT NERVE (it enters the sinus by passing below the
petrosphenoid ligament and accompanies the artery on its
inferolateral aspect).
TRIBUTARIES OF THE CAVERNOUS SINUS
FROM ORBIT
1. Superior ophthalmic vein.
2. Inferior ophthalmic vein.
3. Central vein of retina (sometimes). 
FROM MENINGES
1. Sphenoparietal sinus.
2. Anterior (frontal) trunk of the middle meningeal vein.
FROM BRAIN
1. Superficial middle cerebral vein.
2. Inferior cerebral veins (only few).
COMMUNICATIONS OF CAVERNOUS SINUS
1. Transverse sinus via superior petrosal sinus.
2. Internal jugular vein via inferior petrosal sinus.
3. Pterygoid venous plexus via emissary veins which pass through
foramen ovale, foramen lacerum, and emissary sphenoidal foramen.
4. Facial vein via two routes:
a. Superior ophthalmic vein angular vein facial vein
b. Emissary veins pterygoid venous plexus deep facial vein facial
vein
5. Opposite cavernous sinuses via anterior and posterior intercavernous
sinuses.
6. Superior sagittal sinus via superficial middle cerebral vein and superior
anastomotic vein.
7. Internal vertebral venous plexus, via basilar venous plexus.
APPLIED ANATOMY
1. CAVERNOUS SINUS THROMBOSIS:
• The septic thrombosis of cavernous sinus may be caused by its
numerous communications.
• The commonest cause of thrombosis is the passage of septic
emboli from the dangerous area of the face the through facial
vein—deep facial vein— pterygoid venous plexus—emissary vein.
SIGNS AND SYMPTOMS:
➢ Severe pain in the eye and forehead, due to involvement of the
ophthalmic nerve.
➢ Ophthalmoplegia (paralysis of ocular muscles) due to
involvement of the 3rd, 4th, and 6th cranial nerves.
➢ Marked edema of eyelids with exophthalmos, due to congestion
of orbital veins following obstruction of ophthalmic veins.
2. ARTERIOVENOUS COMMUNICATION:
• If the internal carotid artery is ruptured in the fracture base of the
skull, an arteriovenous communication/fistula is established
between the artery and cavernous sinus.
• Consequently, arterial blood rushes into the cavernous sinus,
enlarging it and forcing blood into the connecting veins.
SIGNS AND SYMPTOMS:
➢ Pulsating exophthalmos; the eyeball protrudes and pulsates with
each heartbeat.
➢ A loud bruit (loud systolic murmur) is easily heard over the eye.
➢ Ophthalmoplegia due to involvement of the 3rd, 4th, and 6th
cranial nerves.
➢ Marked orbital and conjunctival edema due to raised venous
pressure in the cavernous sinus.
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