Book: Cerebri Anatome

Introduction
Thomas Willis's Cerebri Anatome (1664) stands as a foundational text in the history of neuroanatomy and neurology. It presents a systematic, richly illustrated account of the brain and nervous system that moves beyond earlier, fragmentary descriptions to tie structure closely to observed function and clinical phenomena. The work transformed how physicians and anatomists conceptualized the nervous system and laid groundwork for modern neurological science.

Anatomical discoveries
Willis provided detailed descriptions of the major components of the central nervous system, delineating the cerebrum, cerebellum, and brainstem with unprecedented clarity. He distinguished gray from white matter, named and characterized several subcortical structures such as the corpus striatum, and mapped the connections between brain regions and the spinal cord. Attention to the finer organization of cranial and peripheral nerves, and to the course and branching of neural pathways, made Cerebri Anatome a reference for understanding sensory and motor anatomy.

Vasculature and the "circle"
A signature contribution was the meticulous account of the brain's arterial supply, including the arrangement of vessels at the base of the brain that later became known as the Circle of Willis. Willis described collateral circulations and arterial interconnections that explained how blood flow could be redistributed after occlusion, linking vascular anatomy to clinical observations of stroke and focal neurological deficits. His vascular observations remained central to cerebrovascular medicine for centuries.

Methods and illustrations
The book combined careful dissection with precise, instructive illustrations that made complex three-dimensional anatomy accessible. Plates and figures, prepared with notable technical skill, highlighted relationships among nerves, vessels, and brain tissue. Willis and his circle at Oxford emphasized reproducible dissection techniques and comparative anatomy, drawing on human and animal material to reinforce general principles of nervous system organization.

Physiology and clinical insight
Willis did not restrict himself to form; he sought to relate structure to function and to clinical symptoms. He proposed that specific cerebral regions and networks supported voluntary motion, sensation, memory, and emotion, arguing against overly narrow localization theories that confined function to the ventricles alone. Case observations of epilepsy, paralyses, and mental changes were interpreted through anatomical lesions and vascular compromise, advancing a more empirical, clinicopathological approach to neurological disease.

Concepts and terminology
The book introduced terminology and conceptual shifts that shaped subsequent discourse. Willis used language that emphasized the nervous system as an organized, functionally differentiated apparatus rather than a mere collection of organs. Several anatomical names and descriptions from Cerebri Anatome entered the anatomical canon, and the text helped standardize neuroanatomical vocabulary for generations of physicians and anatomists.

Legacy and influence
Cerebri Anatome secured Thomas Willis's reputation as a founder of clinical neurology. It influenced contemporaries and later investigators by insisting that anatomy, careful observation, and clinical correlation must go hand in hand. The book's combination of descriptive precision, physiological speculation grounded in observation, and high-quality illustration set a model for anatomical monographs and directly shaped the study of brain disease, surgery, and vascular neurology. Its enduring citations and the eponymous "Circle of Willis" testify to a lasting impact on medicine and anatomy.