Hypophyseal region--anatomy of the operative approaches.

Landmarks and measurements for the transnasal approach (apertura piriformis, distance to the apertura sinus sphenoidalis) in children and adults are given. Included is the anatomy of the nasal septum, its vessels and nerves. The ostium of the sphenoid sinus, its development, types and dimensions are described. Also shown are the hypophyseal capsule, the hypophyseal vessels and the hypophyseal fossa with its variations and the sella turcica region with its adjacent dural structures (petroclinoid fold, diaphragma sellae, aperture for the internal carotid artery and pituitary cistern). For the intracranial approaches the arterial circle and its branches are important for neurosurgeons. The location, number, width and course of these branches are described. Distances and the most important vessels, which are seen by frontal, frontolateral and pterional approaches, are described.