The pons is a broad band of nerve fibers linking the medulla oblongata and cerebellum with the midbrain. It serves to relay messages sent downstream from the cerebral cortex to the cerebellum, the medulla, and the spinal cord. Shaped as a protuberance resembling a bridge with the brainstem flowing under it like a canal, the pons was first described by Costanzo Varolio and is referred to as the pons Varolii.1,2 But who was this Varolio and what were his achievements?
He was born in 1544 in Bologna, and, as was usual in his time, he first studied philosophy, then graduated in medicine from the University of Padua in 1566. Three years later, the Senate of Bologna appointed him to a newly instituted Chair of Surgery and Anatomy. His main claim to fame is to have dissected the brain from below, thus gaining improved access to its lower surface or base.1-3 Whereas previous dissectors had examined the brain starting from the top, he reversed the approach by separating the brain from the skull and examining it from the bottom upwards.
With his technique, he was able to describe the structures lying at the base of the brain, the nuclei of the medulla oblongata, the cerebellum, and the cranial nerves. He described the pons, which is named after him and which he considered a bridge between the two parts of the cerebellum. His major publication was De Nervis Opticis, in which he described his studies of the optic nerve.
In a second work, Anatomiae sive de resolutione corporis humani, Varolio reported his studies on the corpora cavernosa and the mechanism of penile erection. This had been a subject of study since the days of Galen but the original work had been lost. Varolio described the anatomy with accuracy but mistakenly attributed erection to non-existent erector muscles, an error that persisted for several centuries.
Although details of Varolio’s life are scant, it is believed that in 1572 he went to Rome, taught at the Sapienza University, and became physician to Pope Gregory XIII, who also hailed from Bologna. He practiced successfully as physician and surgeon, and a plaque in his honor refers to his skill in removing bladder stones. He died at an early age in 1575.
- Glickstein M and Gibson A R, Visual cells in the pons of the brain. Scientific American 1976; 235: vol 235, pp 90 (November).
- Zago S and Meravgilia MV. Costanzo Varolio (1543-1575) J Neurol 2009; 256:1195 (July).
- Tubbs RS, Loukas M, Shoja MM. Costanzo Varolio (Constantius Varolius 1543-1575) and the pons Varolii. Neurosurgery 2008;62(issue 3):734 (March)
GEORGE DUNEA, MD, Editor-in-Chief