The pons is the middle part of the brainstem. Nerve cells forming the nuclei located within the pons are mainly responsible for such senses as hearing, equilibrium, taste, touch, and pain, as well as eye movement, and it is also transmitting signals to the cerebellum.

The pons sits in the posterior cranial fossa. It is separated from the medulla oblongata by the inferior pontine sulcus (pontomedullary groove), and from the midbrain - by the superior pontine sulcus.

The pons has a ventral and a dorsal surface.

Ventral surface

The ventral surface of the pons is convex and it lies against the clivus of the occipital bone. There is a groove - the basilar sulcus - crossing the midline of the ventral surface. The basilar artery lies in this sulcus.

The pons gets narrower as it extends laterally and changes into the middle cerebellar peduncles, which connects the pons to the cerebellum.

The border between the pons and the middle cerebellar peduncles is the exit point for the trigeminal nerve (CN V), while the border between the medulla oblongata and pons is the exit point for three other cranial nerves:

Abducens nerve (CN VI) - emerges on the bulbopontine sulcus between the pyramid of the medulla oblongata and the pons;
Facial nerve (CN VII) and the vestibulocochlear nerve (CN VIII) - both emerge from the area called the cerebellopontine angle between the olive and the middle cerebellar peduncles.

Dorsal surface

The dorsal surface of the pons cannot be seen unless the cerebellum is removed, as it is hidden behind it.

The upper part of the rhomboid fossa is formed by the inferior aspect of the dorsal surface of the pons. The upper border of the dorsal surface is known as the superior medullary velum, while the lower border is formed by the striae medullares that are fibers of the arcuate nucleus.

The dorsal surface presents the dorsal median sulcus passing vertically across its midline.

The dorsal median sulcus separates a pair of structures - elevated areas called the medial eminences. The lower edge of each medial eminence is a bit more noticeable than the upper edge. This lower part of the medial eminence is known as the facial colliculus. The facial nerve (CN VII) arches around the abducens nucleus at the site and forms the landmark.

On either side of the facial colliculus, another slightly prominent area is seen – the vestibular area, where some of the vestibular nuclei are located (vestibular nuclei are also found in the upper part of the medulla oblongata).

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Pons