Is the cavernous sinus located within the brain?

The Cavernous Sinus: Location and Anatomy

The cavernous sinus is not located within the brain but is a paired venous plexus situated in an extradural space at the base of the skull adjacent to the brain. 1, 2

Anatomical Position and Structure

• The cavernous sinus occupies a critical position in the skull base, lateral to the sella turcica and pituitary gland
• It is located in an interdural space between the periosteal and meningeal dura layers 3
• Anatomically, it represents a venous pathway that is part of the extradural venous network at the base of the skull, not a true trabeculated venous channel 4

Important Neurovascular Contents

The cavernous sinus contains several critical neurovascular structures:

• Internal carotid artery with its surrounding sympathetic plexus passes through the center 1, 2
• Cranial nerves traversing through or along the cavernous sinus:
  • Abducens nerve (CN VI) courses through the center of the cavernous sinus 1, 2
  • Oculomotor nerve (CN III), trochlear nerve (CN IV), and branches of the trigeminal nerve (CN V1 and CN V2) extend along the lateral wall 1, 2

Clinical Significance

Understanding the extradural location of the cavernous sinus is crucial because:

• Pathology in this region can affect multiple cranial nerves simultaneously, causing characteristic clinical syndromes 1
• Cavernous sinus lesions can result in isolated or multiple cranial neuropathies, particularly involving the abducens and trigeminal nerves 1
• Common pathologies affecting this region include:
  • Vascular lesions (aneurysms, carotid-cavernous fistulas, thrombosis) 2, 5
  • Tumors (pituitary adenomas, meningiomas, schwannomas) 2, 5
  • Inflammatory and infectious processes 2, 5

Anatomical Relationships

• The cavernous sinus has important relationships with surrounding structures:
  • Medially: pituitary gland and sphenoid sinus
  • Laterally: temporal lobe (but separated by dural layers)
  • Superiorly: anterior clinoid process
  • Posteriorly: petrous apex and clivus
  • Anteriorly: superior orbital fissure 6

Understanding that the cavernous sinus is an extradural structure rather than within the brain itself is essential for proper diagnosis and management of pathologies affecting this region.