Cavernous sinuses

CAVERNOUS SINUS

Definition Size Location Structure Extent Relations Lateral Wall Medial Aspect Tributaries Draining Channels Communications Expulsion of Blood Clinical Anatomy
01

Definition

  • Cavernous sinus is a large dural venous sinus.
  • It lies between the two layers of dura mater.
02

Size

Length

About 2 cm long.

Width

About 1 cm wide.

03

Location

  • Each cavernous sinus lies in the middle cranial fossa.
  • It lies on either side of the body of sphenoid bone.
04

Parts / Structure

  • The cavernous sinus lies between two layers of dura mater.
  • Each cavernous sinus has:
    1. Roof
    2. Floor
    3. Medial wall
    4. Lateral wall

Formation of Walls

1. Roof and Lateral Wall

Formed by the meningeal layer of dura mater.

2. Floor and Medial Wall

Formed by the endosteal layer of dura mater.

Interior of Cavernous Sinus

  • The interior of the cavernous sinus is divided into a number of caverns by trabeculae.
  • The trabeculae are much less conspicuous in the living than in the dead.
05

Extent

Anteriorly

Up to the medial end of the superior orbital fissure.

Posteriorly

Up to the apex of the petrous part of temporal bone.

06

Relations

Superior Relations

  • Optic tract
  • Optic chiasma
  • Olfactory tract
  • Internal carotid artery
  • Anterior perforated substance

Inferior Relations

  • Foramen lacerum
  • Junction of the body and greater wing of sphenoid bone

Medial Relations

  • Hypophysis cerebri
  • Sphenoidal air sinus

Lateral Relation

  • Temporal lobe with uncus

Anterior Relations

  • Superior orbital fissure
  • Apex of the orbit

Posterior Relations

  • Apex of the petrous temporal bone
  • Crus cerebri of the midbrain
07

Structures Within the Lateral Wall of the Sinus

From above downwards:

  1. Oculomotor nerve
  2. Trochlear nerve
  3. Ophthalmic nerve
  4. Maxillary nerve.

Oculomotor Nerve

  • In the anterior part of the sinus, it divides into:
    • Superior division
    • Inferior division
  • These leave the sinus through the superior orbital fissure.

Trochlear Nerve

  • In the anterior part of the sinus, it crosses superficial to the oculomotor nerve.
  • It enters the orbit through the superior orbital fissure.

Ophthalmic Nerve

  • In the anterior part of the sinus, it divides into:
    • Lacrimal nerve
    • Frontal nerve
    • Nasociliary nerve

Maxillary Nerve

  • It does not pass through the cavernous sinus or its lateral wall.
  • It courses beneath the dura mater of the middle cranial fossa.
  • It passes below the level of the cavernous sinus by piercing the cavum trigeminale.
  • The structures in the lateral wall and on the medial aspect of the sinus are separated from blood by the endothelial lining.
08

Structures Passing Through the Medial Aspect of the Sinus

1. Internal Carotid Artery

  • Accompanied by the venous and sympathetic plexus around it.

2. Abducent Nerve

  • The abducent nerve enters the cavernous sinus by passing inferior to the petrosphenoidal ligament within a dural tunnel called Dorello’s canal.
  • It enters just posterior to the short ascending portion of the cavernous carotid artery.
  • It then runs on the inferolateral side of the horizontal portion of the cavernous carotid artery.
  • It lies just medial to the ophthalmic nerve at the lateral wall of the sinus.
  • This region is known as the infratrochlear or Parkinson’s triangle.
  • Parkinson’s triangle gives access to:
    • Horizontal portion of the cavernous carotid artery
    • Abducent nerve.
09

Tributaries / Incoming Channels

A. From the Orbit

  1. Superior ophthalmic vein
  2. Branch of the inferior ophthalmic vein, or sometimes the vein itself
  3. Central vein of the retina
    • May drain either into the:
      • Superior ophthalmic vein, or
      • Cavernous sinus.

B. From the Brain

  1. Superficial middle cerebral vein
  2. Inferior cerebral veins from the temporal lobe.

C. From the Meninges

  1. Sphenoparietal sinus
  2. Frontal trunk of the middle meningeal vein

D. From the Face

Facial vein → Deep facial vein → Pterygoid plexus → Emissary vein → Cavernous sinus
10

Draining Channels / Communications

1. Into Transverse Sinus

Through the superior petrosal sinus.

2. Into Internal Jugular Vein

  • Through the inferior petrosal sinus.
  • Also through a plexus around the internal carotid artery.

3. Into Pterygoid Plexus of Veins

Through emissary veins passing through:

  • Foramen ovale
  • Foramen lacerum
  • Emissary sphenoidal foramen

4. Into Facial Vein

Through the superior ophthalmic vein.

5. Communication Between Right and Left Cavernous Sinuses

The right and left cavernous sinuses communicate with each other through:

  • Anterior intercavernous sinus
  • Posterior intercavernous sinus
  • Basilar plexus of veins
  • All these communications are valveless.
  • Blood can flow through them in either direction.
11

Other Communications

  • Transverse sinus ↔ Superior petrosal sinus
  • Internal jugular vein ↔ Inferior petrosal sinus
  • Pterygoid venous plexus ↔ Emissary veins
  • Facial vein ↔ Superior ophthalmic vein and emissary vein
  • Superior sagittal sinus ↔ Superficial middle cerebral vein and superior anastomotic vein
  • Internal vertebral venous plexus ↔ Basilar venous plexus
  • Opposite cavernous sinus ↔ Anterior and posterior intercavernous sinuses.
12

Factors Helping Expulsion of Blood from the Sinus

1.

Expansile pulsations of the internal carotid artery within the sinus

2.

Gravity

3.

Position of the head.

13

Clinical Anatomy

Cavernous Sinus Thrombosis

  • Thrombosis of the cavernous sinus may be caused by sepsis in:
    • Dangerous area of the face
    • Nasal cavities
    • Paranasal air sinuses
  • This gives rise to the following symptoms:

Nervous Symptoms

  1. Severe pain in the eye and forehead
    • In the area of distribution of the ophthalmic nerve.
  2. Involvement of the 3rd, 4th and 6th cranial nerves
    • Results in paralysis of the muscles supplied.

Clinical Integration

  • Cavernous sinus thrombosis
  • Carotid-cavernous sinus fistula.
Cavernous Sinus — Study Notes