Pons

The pons is one of the three parts of the brainstem, sitting below the midbrain and above the medulla oblongata, directly in front of the cerebellum. Its name comes from the Latin for "bridge," which describes its main job: it is a major relay station carrying signals between the cerebral cortex above and the cerebellum and medulla below.

Functionally, the pons contributes to several automatic processes. Its respiratory centers work with the medulla to smooth and regulate the breathing rhythm. It also participates in sleep and arousal — including REM sleep — and serves as the point of origin for several cranial nerves, including the trigeminal nerve (cranial nerve V), which carries facial sensation and controls chewing.

The pons matters clinically and conceptually because the brainstem as a whole controls life-sustaining functions. Damage to the pons can disrupt breathing patterns, facial sensation and movement, eye movements, and consciousness — which is why exam questions often pair a described deficit with the brainstem structure responsible.

On the MCAT, the pons appears in the psychological, social, and biological foundations section, within the biological bases of behavior and the components of the central nervous system. Be able to place the pons between the midbrain and medulla, identify it as a cerebrum–cerebellum relay, and associate it with breathing regulation and sleep.