Fig. 1.5 Surgical views from posterior approaches. (a)
The occipital transtentorial approaches exploit the corri-
dor between the occipital lobe and falx-tentorium to
access the posterior aspect of the tentorial incisura, dorsal
mesencephalon, and pineal region. The vein of Galen
complex is visualized deep in the surgical field. (b)
Enlarged view of the occipital transtentorial approach.
The pineal region and Galenian venous complex are
exposed. (c) Posterior view of the suboccipital craniot-
omy. The suboccipital cerebellar surface is bordered by
the transverse and sigmoid sinuses. (d) Posterior view of
the supracerebellar infratentorial approach. The pineal
gland and superior colliculi are exposed along with tribu-
taries to the vein of Galen. The basal vein of Rosenthal,
the internal cerebral veins, and the precentral veins are
seen draining into the vein of Galen, which in turn empties
in the straight sinus at the midline of the tentorium. (e)
Posterior inferior view of the telovelar approach. The cer-
ebellar tonsil is retracted to expose the inferior roof of the
fourth ventricle formed by the inferior medullary velum
and tela choroidea, which anchors the fourth ventricle
choroid plexus. (f) View of the fourth ventricle through
the telovelar approach. Division of the tela choroidea and
velum exposes the floor of the fourth ventricle, lateral
recesses and the aqueduct of Sylvius. (g) Posterior view of
the floor of the fourth ventricle. The protuberances identi-
fied in the floor of the fourth ventricle include the facial
colliculus (abducens nucleus), the hypoglossal trigone,
and the vagal trigone. The lateral recess communicates
with the cerebellopontine angle through the foramen of
Luschka. The superior and inferior cerebellar peduncles
contribute to the lateral walls of the fourth ventricle