The pons is the largest part of the human brainstem by volume.
The brainstem has three main divisions: the midbrain at the top, the pons in the middle, and the medulla oblongata at the bottom. The pons forms a prominent bulge on the front of the brainstem and contains dense bundles of fibers connecting the cerebrum with the cerebellum and spinal cord.
Its name means “bridge,” reflecting the appearance and function of its transverse fibers. Neurons in the pons also participate in sleep, arousal, breathing, facial movement, chewing, hearing, and balance. The fourth ventricle lies behind the pons and upper medulla.
The pons should not be confused with the entire brainstem. The midbrain contains important visual and motor pathways, while the medulla contains vital cardiovascular and respiratory control networks. Because these regions are tightly connected, a brainstem injury can produce a combination of movement, sensory, eye-movement, consciousness, and autonomic problems.