Microanatomical Studies Of Paraclinoid Region And The Lateral Wall Of Cavernous Sinus

Objective: To understand the microanatomical structures of the paraclinoid region and the lateral wall of cavernous sinus (CS) and provide safe operative approaches for direct microsurgical operation to the CS and sellar regions. Methods: 30 specimen from 15 dry skull bases and 30 specimen from 15 adult cadaver heads were used to dissect, observe and measure under microscope. Results: (1)The Anterior clinoid process is a posterior and medial continuation.Its lenth is 10.29±0.78mmand its width is 9.03±0.71mm. (2)The opticstrut separate optic canal from superior orbital fissure .Its lenth is 5.66±0.67mm and its width is 5.72±0.73mm. (3)The clinoid segment of the ICA is between the distal dural ring and the proximal dural ring and its length is 5.14±0.74mm. This portion of the ICA can be directly observed only after removal of the clinoid process. (4) The distal dural ring is a thick membrane that fuses with the adventitia of the ICA and its thickness is (0.52±0.08) mm; The proximal dural ring loosely surrounds the entire length of clinoid segment of ICA and admits a variable number of veins from the cavernous plexus that accompany this segment. The thickness of the proximal dural ring is (0.22±0.06) mm. (5)93% of the ophthalmic arteries arise distal to the distal dural ring in 1-2mm.and its diameter is (1.78± 0.46)mm. (6)There were Parkinson trigone, paramedical trigone, Mullan trigone, Lateral trigone, Glasscock trigone and Kawase trigone were in the lateral wall and its surrounding. Conclusions: (1)The clinoid segment of the ICA is intracavernous in most cases.(2)For exposing the clinoid segment of the ICA should cutting the distal dural ring from its medial margin, the distal dural ring(3)Ophthalmic arteries arise from the C2 segement of ICA.(4)The trigones of the CS could provide safe approaches for direct expose the CS .