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Thomas WillisThomas Willis (1621-1673) was an English physician who played an important part in the history of the science of anatomy and was a co-founder of the Royal Society (1662). Willis worked as a physician in Westminster, London, and from 1660 until his death was Sedleian Professor of Natural Philosophy at Oxford. He was a pioneer in research into the anatomy of the brain, nervous system and muscles. The "circle of Willis", a part of the brain's vascular system, was his discovery. His anatomy of the brain and nerves, as described in his Cerebri anatomi of 1664, is so minute and elaborate, and abounds so much in new information, that it presents an enormous contrast with the vague and meagre efforts of his predecessors. This work was not the result of his own personal and unaided exertions; he acknowledged his debt to Sir Christopher Wren and Thomas Millington, and his fellow-anatomist Richard Lower. Wren was the illustrator of the magnificent figures in the book. Willis was the first natural philosopher to use the term "reflex action" to describe elemental acts of the nervous system. He also wrote Pathologiae Cerebri et Nervosi Generis Specimen, 1667 (An Essay of the Pathology of the Brain and Nervous Stock) and of De Anima Brutorum, 1672 (Discourses Concerning the Souls of Brutes). Willis was the first to number the cranial nerves in the order in which they are now usually enumerated by anatomists. His observation of the connection of the eighth pair with the slender nerve which issues from the beginning of the spinal cord is known to all. He remarked the parallel lines of the mesolobe, afterwards minutely described by Felix Vicq d'Azyr. He seems to have recognized the communication of the convoluted surface of the brain and that between the lateral cavities beneath the fornix. He first described the corpora striata and the optic thalamus; the pons, which to which he gave the name of annular protuberance, and the mammillary bodies, behind the infundibulum. In the cerebellum he remarked about the arborescent arrangement of the white and grey matter, and gave a good account of the carotid arteries and the communications which they make with the branches of the basilar artery. In relation to the search for the brain correlates of the mind, Willis extended the concepts proposed by the Roman physician Galen, that the brain was the organ responsible for the excretion of animal spirits (which was tought to originate from the cribiform plate, a bone in the base of the skull, overlying the nasal cavity). Willis proposed that the choroid plexus was responsible for the absorption of cerebrospinal fluid. Later, in De Anima Brutorum, he proposed that the corpus striatum received all sensory information, while the corpus callosum was associated with imagination and the cerebral cortex with memory. Willis astonishing insightful forays into the anatomy and physiology of the brain were extremely influential. His mark was indelible and divided the field into two periods. Willis, Thomas Willis, Thomas Willis, Thomas Willis, Thomas Willis, Thomas Willis, Thomas
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