QS Study

Cavernous sinus is a large venous space between two layers of dura mater. It is a part of the brain’s dural venous sinus and contains multiple neuro-vasculatures. A cavernous sinus thrombosis is a blood clot within the cavernous sinus. This clot causes the cavernous sinus syndrome.

Boundaries

  • roof: a fold of dura mater attached to the anterior and middle clinoid processes
  • anterior wall: medial end of the superior orbital fissure
  • posterior wall: petrous apex
  • medial wall: endosteum overlying the body of the sphenoid bone
  • lateral wall: dura mater from the ridge of the roof to the floor of the middle cranial fossa
  • floor: endosteum overlying the base of the greater wing of the sphenoid bone.

 Cavernous Sinus 1

Fig: Cavernous Sinus Boundaries

Relations – Medially, the sinus is adjacent to the lateral walls of the pituitary fossa with the pituitary gland, the sphenoid bone, and its air sinus.

(A) Structures outside the sinus:

(i) Superiorly –

  • Optic tract.
  • Internal carotid artery.
  • Anterior perforated substance.

(ii) Inferiorly

  • Foramen lacerum.
  • Sphenoid bone.

(iii) Medially

  • Hypophysis cerebri.
  • Sphenoidal air sinus.

(iv) Laterally

  • Temporal lobe with uncus.

(v) Anteriorly

  • Superior orbital fissure.
  • The apex of the orbit.

(vi) Posteriorly

  • An apex of the petrous temporal bone.
  • Crus cerebri of the midbrain.

(B) Structures in the lateral wall of sinus: (above downwards)

  • Oculomotor nerve.
  • Trochlear nerve.
  • Ophthalmic nerve.
  • Maxillary nerve.
  • Trigeminal ganglion.

(C) Structures passing through the center of the sinus:

  • Internal carotid artery.
  • Abducent nerve.

Clinical importance:

Thrombosis of the cavernous sinus may be caused by sepsis in the dangerous area of the face, in the nasal cavities & in the paranasal air sinuses. These lead to nervous & venous symptoms.

Head injury may cause a communication between the cavernous sinus & the internal carotid & may lead artery pulsating exophthalmos.

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