Skull Base Surgery of the Posterior Fossa

© Springer International Publishing AG 2018 3
W.T. Couldwell (ed.), Skull Base Surgery of the Posterior Fossa,
https://doi.org/10.1007/978-3-319-67038-6_

Surgical Anatomy of the Posterior

Fossa

Jaafar Basma and Jeffrey Sorenson

J. Basma, MD • J. Sorenson, MD (*)
University of Tennessee, 847 Monroe Avenue,
Suite 427, Memphis, TN 38163, USA
e-mail: [email protected];
[email protected]

1

Abbreviations

AICA Anterior inferior cerebellar artery
IAC Internal auditory canal
ICA Internal carotid artery
III Oculomotor nerve
IV Trochlear nerve
IX Glossopharyngeal nerve
PCA Posterior cerebral artery
PICA Posterior inferior cerebellar artery
SCA Superior cerebellar artery
SCC Semicircular canal
V Trigeminal nerve
VI Abducens nerve
VII Facial nerve
VIII Vestibulocochlear nerve
X Vagus nerve
XI Spinal accessory nerve
XII Hypoglossal nerve

Introduction

The posterior fossa is the most complex and surgi-
cally challenging region of human anatomy. The
high density of eloquent neurovascular structures

in this region necessitates a wide variety of surgical

approaches. Because small surgical errors here

have the potential to cause significant morbidity,

the posterior fossa surgeon must become an expert

in this anatomy. The images used in this chapter

were created in Dr. Al Rhoton Jr.’s laboratory with

the express purpose of making surgery in the pos-

terior fossa more “accurate, gentle, and safe.” For

more in-depth study, please refer to his textbook

[ 1 ] or the online Rhoton Collection [ 2 ]. We will

first examine the enclosure of the posterior fossa

which is formed by the bowl-shaped skull base

covered by the pitched tentorium. We will then

review Dr. Rhoton’s “rule of three,” which divides

the neurovascular contents of the posterior fossa

into three groups of structures, each organized

around a major posterior fossa artery. The cranial

nerves, arachnoid cisterns, and special regions of

the posterior fossa are then surveyed from the per-

spective of various surgical approaches.

Enclosure of the Posterior Fossa

Skull Base

The posterior fossa is bounded primarily by three

bones that form a bowl-shaped cavity (Fig. 1.1a).

The occipital bone forms the rounded squamosal

posterior wall of this cavity, as well as the floor, and

most of the anterior wall (clivus). The sphenoid

bone contributes the upper third of the clivus, which