1. TUMA/KCMUCO/MD.2021/2022/TZ/5457
cavernous sinus
Central question; describe cavernous sinus and its content
The cavernous sinus, a large venous plexus, is located on each side of the sella turcica
on the upper surface of the body of the sphenoid, which contains the sphenoid (air)
sinus
The cavernous sinus consists of a venous plexus of extremely thin-walled veins that
extends from the superior orbital fissure anteriorly to the apex of the petrous part of
the temporal bone posteriorly.
It receives blood from the superior and inferior ophthalmic veins, superficial middle
cerebral vein, and sphenoparietal sinus. The venous channels in these sinuses
communicate with each other through venous channels anterior and posterior to the
stalk of the pituitary gland the intercavernous sinuses and sometimes through veins
inferior to the pituitary gland.
The cavernous sinuses drain posteroinferiorly through the superior and inferior
petrosal sinuses and emissary veins to the basilar and pterygoid plexuses (Fig. 7.29B).
2. CONTENTS
Inside each cavernous sinus is
the internal carotid artery with its small branches, surrounded
by the carotid plexus of sympathetic nerve(s),
Abducent nerve (CN VI); Courses through cavernous sinus
The oculomotor (CN III); Runs in lateral wall of cavernous
sinus
trochlear (CN IV) nerves; Runs in lateral wall of cavernous
sinus
two of the three divisions of the trigeminal nerve (CN V) are
embedded in the lateral wall of the sinus.
3. The artery, carrying warm blood from the body’s core, traverses the sinus filled with
cooler blood returning from the capillaries of the body’s periphery, allowing for heat
exchange to conserve energy or cool the arterial blood.
This does not appear to be as important in humans as it is in running animals (e.g.,
horses and cheetahs) in which the carotid artery runs a longer, more tortuous course
through the cavernous sinuses, allowing cooling of blood before it enters the brain.
Pulsations of the artery within the cavernous sinus are said to promote propulsion of
venous blood from the sinus, as does gravity.
The superior petrosal sinuses run from the posterior ends of the veins making up the
cavernous sinus to the transverse sinuses at the site where these sinuses curve
inferiorly to form the sigmoid sinuses.
Each superior petrosal sinus lies in the anterolateral attached margin of the tentorium
cerebelli, which attaches to the superior border (crest) of the petrous part of the
temporal bone.
The inferior petrosal sinuses also commence at the posterior end of the cavernous
sinus. Each inferior petrosal sinus runs in a groove between the petrous part of the
temporal bone and the basilar part of the occipital bone.
The inferior petrosal sinuses drain the cavernous sinus directly into the transition of
the sigmoid sinus to the IJV at the jugular foramen. The basilar plexus connects the
inferior petrosal sinuses
4. CLINICAL POINTS
I. Thrombophlebitis of Facial Vein
The facial vein makes clinically important connections with the cavernous sinus
through the superior ophthalmic vein, and the pterygoid venous plexus through the
inferior ophthalmic and deep facial veins.
Because of these connections, an infection of the face may spread to the cavernous
sinus and pterygoid venous plexus. Blood from the medial angle of the eye, nose, and
lips usually drains inferiorly through the facial vein, especially when a person is erect.
Because the facial vein has no valves, blood may pass through it in the opposite
direction; consequently, venous blood from the face may enter the cavernous sinus.
In individuals with thrombophlebitis of the facial vein inflammation of the facial
vein with secondary thrombus (clot) formation pieces of an infected clot may
extend into the intracranial venous system and produce thrombophlebitis of the
cavernous sinus
II. Occlusion of Cerebral Veins and Dural Venous Sinuses
Occlusion of cerebral veins and dural venous sinuses may result from thrombi (clots),
thrombophlebitis (venous inflammation), or tumors (e.g., meningiomas).
The dural venous sinuses most frequently thrombosed are the transverse, cavernous,
and superior sagittal sinuses.
The facial veins make clinically important connections with the cavernous sinus
through the superior ophthalmic veins.
Cavernous sinus thrombosis usually results from infections in the orbit, nasal sinuses,
and superior part of the face (the danger triangle). In persons with thrombophlebitis of
5. the facial vein, pieces of an infected thrombus may extend into the cavernous sinus,
producing thrombophlebitis of the cavernous sinus.
The infection usually involves only one sinus initially but may spread to the opposite
side through the intercavernous sinuses. Thrombophlebitis of the cavernous sinus may
affect the abducent nerve as it traverses the sinus and may also effect the nerves
embedded within the lateral wall of the sinus.
Septic thrombosis of the cavernous sinus often results in the development of acute
meningitis
III. Fractures of Cranial Base
In fractures of the cranial base, the internal carotid artery may be torn, producing an
arteriovenous fistula within the sinus. Arterial blood rushes into the cavernous sinus,
enlarging it and forcing retrograde blood flow into its venous tributaries, especially
the ophthalmic veins.
As a result, the eyeball protrudes (exophthalmos) and the conjunctiva becomes
engorged (chemosis). The protruding eyeball pulsates in synchrony with the radial
pulse, a phenomenon known as pulsating exophthalmos.
Because CN III, CN IV, CN V1, CN V2, and CN VI lie in or close to the lateral wall
of the cavernous sinus, these nerves may also be affected when the sinus is injured.
The central vein of the retina usually enters the cavernous sinus directly, but it may
join one of the ophthalmic veins.
The vortex, or vorticose veins, from the vascular layer of the eyeball drain into the
inferior ophthalmic vein. The scleral venous sinus is a vascular structure encircling
the anterior chamber of the eyeball through which the aqueous humor is returned to
the blood circulation.
The pterygoid venous plexus is located partly between the temporalis and the
pterygoid muscles. It is the venous equivalent of most of the maxillary artery—that is,
most of the veins that accompany the branches of the maxillary artery drain into this
plexus.
The plexus anastomoses anteriorly with the facial vein via the deep facial vein and
superiorly with the cavernous sinus via emissary veins
