|Died||26 April 1558|
|Other names||Ioannes Fernelius|
|Institutions||University of Paris|
|Notable students||Andreas Vesalius|
Jean François Fernel (Latinized as Ioannes Fernelius; 1497 - 26 April 1558) was a French physician who introduced the term "physiology" to describe the study of the body's function. He was the first person to describe the spinal canal. The lunar crater Fernelius is named after him.
He was born in Montdidier and, after receiving his early education at Clermont, he entered the College of Sainte-Barbe, Paris. At first he devoted himself to mathematical and astronomical studies; but from 1534 he gave himself up entirely to medicine, in which he graduated in 1530. His general erudition, and the skill and success with which he sought to revive the study of the old Greek physicians, gained him a reputation, and ultimately the office of physician to the court. Catherine de' Medici, wife of King Henry II of France, sought his advice regarding their difficulty in conceiving a child. He practiced with success, and at his death at Paris in 1558 left him a large fortune. His remains were entombed at the Church of Saint-Jacques-de-la-Boucherie.
Fernel's Cosmotheoria (1528) records a determination of a degree of arc of the meridian, which he made by counting the revolutions of his carriage wheels on a journey between Paris and Amiens. Using his measurements he calculated the circumference of the earth to within one percent of the correct value. His works on mathematical and astronomical subjects also include Monalosphaerium, sive astrolabii genus, generalis horarii structura et usus (1526), and De proportionibus (1528).
As a physician and professor of medicine at the Collège de Coenouailles for over 20 years, Fernel is credited with the neologism, physiology, a discipline which became one of the central topics of education and research in the field of medicine. His early understanding of physiology, especially of the brain, was represented by three statements commonly quoted in physiological history:
His medical works included De naturali parte medicinae (1542), De vacuandi ratione (1545), De abditis rerum causis (1548) which included a chapter on angelology and demonology. What has been called his "crowning work",Universa Medicina, comprises three parts: the Physiologia (developed from the De naturali parte), the Pathologia, and the Therapeutice.