The Brainstem

The brainstem is a CNS structure that acts as the highway for motor and sensory pathways travelling between the spinal cord and the cerebral cortex and houses important grey matter structures such as the nuclei for cranial nerves III to XI as well as the reticular activating system that is responsible for consciousness. It is divided into three sections, rostral to caudal: the midbrain, the pons and the medulla. Each section of the brainstem houses its own set of nuclei, tracts and structures, and has its own signature look on cross-section, all of which serve as important landmarks on imaging.

Midbrain

Rostral midbrain:

Caudal midbrain:

Pons

Rostral pons:

Caudal pons:

Medulla

Mnemonics

The brainstem, with all the structures and tracts it houses, is very complicated to learn and remember! In light of this, certain useful mnemonics have been developed, such as the Rule of 4 that you can read more about here.