Cavernous sinus

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Cavernous sinus

ANATOMY:

  • There are 2 Cavernous Sinuses on either side of Sella tursica irregular form larger behind than front.
  • Extends from sphenoid fissure to petrous apex.
  • Each cavernous sinus is a large venous space situated in the middle cranial fossa on either side of the body of sphenoid bone. Its interior is divided into a number of trabeculae or caverns.
  • The floor of the sinus is formed by the endosteal dura mater. The lateral wall, roof and medial wall are formed by the meningeal duramater.
OSSEOUS RELATIONSHIP:
  • Related to sphenoid bone and sella tursica.
  • On each side of fossa is S shaped groove lodges Internal carotid artery.
  • Fibrous or osseous bridge exist between Anterior, Middle or Posterior Compartment.
  • Connection between AC and MC makes distal end of carotid sulcus to carotico-clinoid foramen.
Structures in the lateral wall of the sinus from above downwards:
  1. Oculomotor nerve
  2. Trochlear nerve
  3. Ophthalmic nerve- in the anterior part of the sinus, it divides into the lacrimal, frontal and nasociliary nerves.
  4. Maxillary nerve- it leaves the sinus by passing through the foramen rotundum on its way to the pterygopalatine fossa.
  5. Trigeminal ganglion- the ganglion and its dural cave project into the posterior part of the lateral wall of the sinus.
Structures passing through the center of the sinus:
 
  1. Internal carotid artery with the venous and sympathetic plexus around it.
  2. Abducent nerve, inferolateral to the internal carotid artery.
Tributaries (incoming channels) of cavernous sinus
 
  1. Superior ophthalmic vein.
  2. A branch of inferior ophthalmic vein or sometimes vein itself.
  3. Central vein of retina (it may also drain into superior pophthalmic vein).
  4. Superficial middle cerebral vein.
  5. Inferior cerebral vein.
  6. Sphenoparietal sinus.
  7. Frontal trunk of middle meningeal vein (it may also drain into pterygoid plexus or into sphenoparietal sinus).
Draining channels (communications) of cavernous sinus
 
  1. Into transverse sinus through superior petrosal sinus.
  2. Into internal jugular vein through inferior petrosal sinus and through a plexus around the ICA.
  3. Into pterygoid plexus of veins through emissary vein.
  4. Into facial vein through superior ophthalmic vein.
  5. Right and left cavernous sinus communicates with each other by anterior and posterior intercavernous sinuses and through basilar plexus of veins.
 VENOUS COMPARTMENT:
  • Divided into medial, lateral anteroinferior and posterosuperior compartments.
  • As afferents each CS receives spheno parietal sinus, frontal trunk of middle meningeal, superior & inferior ophthalmic vein, superficial middle cerebral vein, inferior cerebral vein
  • Superior opthalmic vein connects facial vein to cavernous sinus.
  • Veins communicating the cavernous sinus to pterygoid plexus pass through fossa of vesalius.
  • On efferent side, CS drains into Inferior Petrosal sinus.

NEURAL COMPARTMENT:

  • III,IV,V1,V2  lie between 2 dural layers that form lateral wall of CS.
  • Superficial layer of lateral wall is a thick layer formed by the duramater.
  • This layer continues anteriorly over the superior surface of Anterior clinoid process(ACP) enveloping ICA to form distal dural ring.
  • The inner layer has a reticular consistency and incomplete in 40% of cases.
  • Through the inner layer run III,IV and V1.
  • The inner layer extents anteriorly and inferiorly to ACP surrounds anterior loop of ICA and forms the proximl ring and also anterior loop of CS.
  • III N pierces CS in the middle of  occulomotor trigone in the upper part of lateral wall of CS.
  • Courses anteriorly and leaves the CS on nhe inferolateral surface of ACP
  • IV th N enters posterolateral to III N courses anterolateroinferior to enter the Superior Orbital Fissure.
  • V1 enters the lower part of lateral wall of CS runs anteriorly and upwards to pass through SOF
  • VI enters CS through Dorello`s canal and courses inside the sinus lateral to ICA.
  • This canal is limited superiorly by petroclinoid ligament also known as Gruber`s ligament.

APPLIED ANATOMY

  • Cavernous sinus thrombosis may be caused by infection in dangerous area of face, nasal,cavities and paranasal sinuses. It presents as:-
  1. Nervous symptoms:– Severe pain in the distribution of ophthalmic nerve. Involvement of 3rd, 4th, and 6th cranial nerves causes paralysis of extraocular muscles with diplopia.
  2. Venous symptoms:- Edema of eyelids, cornea and root of nose with exopthalmos.
  • Commmunication b/w cavernous sinus and ICA, after trauma, may cause pulsatile exopthalmos.
Exam Question
 
  • Structures passing through cavernous sinus are internal carotid artery & abducent nerve.
  • As afferents each CS receives spheno parietal sinus, frontal trunk of middle meningeal, superior & inferior ophthalmic vein, superficial middle cerebral vein, inferior cerebral vein.
  • III , IV, V1, V2, VI are the cranial nerves that travels through the cavernous sinus.
  • Superior ophthalmic vein directly communicates with cavernous sinus.
  • Abducent nerve & internal carotid artery Are the direct content of cavernous sinus
  • Facial vein is connected to cavernous sinus via superior opthalmic vein.
  • Veins communicating the cavernous sinus to pterygoid plexus pass through fossa of vesalius.
Don’t Forget to Solve all the previous Year Question asked on Cavernous sinus

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