Anatomy of the Brainstem

Due to its compact and eloquent anatomy, the brainstem is an unforgiving surgical site. Therefore, detailed knowledge of this anatomy is essential while planning an approach into the brainstem to remove a lesion. In this chapter, we describe surface landmarks of the midbrain, pons and medulla, as well as their relationships to the internal structures that are used to define the safe entry zones. We also review Rhoton’s Rule of Three, which is useful for learning the neurovascular relationship of the posterior fossa. Familiarity with this anatomy should help the surgeon choose the approach with the least morbidity.