The optic canal transmits the optic nerve with its dural and arachnoid coverings and also the ophthalmic artery from the orbit to the cranial cavity. In our material we determined a mean length of 9.8 mm for the upper wall of the optic canal and 4.63 mm for the lower wall. The medial wall of the canal is 11.4 (8–16) mm long, the lateral 10.79 (8.5–15) mm long (Lang and Oehmann 1976; Lang and Reiter 1985). The posterior superior wall of the optic canal is overlapped by a dural layer 2.58 (0.5–8.0) mm long composed of transverse fibers. Bony substance is lost from this area in postnatal life, leaving only the dura mater. We found in our material that the ophthalmic artery, with an outer diameter of 1.47 (0.9–2.1) mm (Lang and Kageyama, in press), can emerge in the subarachnoid space (approx. 47% of cases), at the junction between the dural opening of the internal carotid artery and subdural space (33.3%), or even in the cavernous sinus (approx. 18%) (Engel 1975).
KeywordsDura Dial Nial Haas Rounded
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