The pons is an approximately 2cm long “knob-like” process located deep in the middle of the brain.
One can visualize the pons as a box...
Top - midbrain
Bottom - medulla
Front - pontine cistern and the clivus (the slanted bony bottom part of the skull)
Back - 4th ventricle.
Sides - Cerebellar Penduncles
The pons itself is divided into a back (medically called dorsal) part and a front (medically called ventral) part. The back part is often called the pontine tegmentum whereas the front part is called the ventral or basal pons. There are 4 paired cranial nerves (one on the left and one on the right) that start in the pons.
The cranial nerves are nerves that control the special senses and the movement/sensation of the head and neck. Four sets of cranial nerves come from the pons.
The pontine tegmentum is against the 4th ventricle and contains an origin of 4 cranial nerve (5th, 6th, 7th and 8th nerve), the reticular activating system, ascending/descending nerve tracts as well as other nuclei.
The ventral pons consists of nerve fibers tracts going up and down as well as across the area. It acts as a massive relay station connecting the cerebral cortex to the cerebellum on the other side through a structure called the cerebellar peduncles.
The cerebellar peducles (also called brachium pontis) are the nerve superhighway from the pons to the cerebellum. It is interesting to note that both the cerebellum and the pons share the same developmental seed as the embryonic metencephalon.
The area above the blue is the tegementum.
The area below the blue is the ventral pons.
The crossing fibers in the vental pons continue to the sides to form the cerebellar peduncles.
Last update July 2008