The Cerebellopontine Angle and Posterior Fossa Cranial Nerves by the Retrosigmoid Approach

The cerebellopontine angle is located between the superior and inferior limbs of the angular cerebellopontine fissure formed by the petrosal cerebellar surface folding around the pons and middle cerebellar peduncle (Fig. 4.1). The cerebellopontine fissure opens medially and has superior and inferior limbs that meet at a lateral apex. The fourth through the eleventh cranial nerves are located near or within the angular space between the two limbs commonly referred to as the cerebellopontine angle (Fig. 4.1). The trochlear and trigeminal nerves are located near the fissure's superior limb and the glossopharyngeal, vagus, and accessory nerves are located near the inferior limb. The abducens nerve is located near the base of the fissure, along a line connecting the anterior ends of the superior and inferior limbs. This description of the cranial nerves and operative approaches to the cerebellopontine angle is organized around the three neurovascular complexes,...