Preul, Mark C.

British anatomical physiology in the early 19th century evolved from the work of William Harvey, Thomas Willis, and William Hunter, who emphasized cerebral functional localization, integrating physiology and anatomy. This novel perspective was championed by Herbert Mayo (1796–1852). A student of Charles Bell at the Middlesex Hospital in London, Mayo subsequently became a surgeon there in 1818 and later a professor of anatomy and surgery. His experiments on the motor functions of the seventh cranial nerve and sensorimotor functions of the fifth cranial nerve brought him renown. Mayo, inspired by Johann Christian Reil, also conducted the first accurate brainstem dissections, developed innovative tissue preservation methods, and provided detailed descriptions of key fiber tracts. Mayo’s 1822–1823 Anatomical and Physiological Commentaries and 1827 A Series of Engravings Intended to Illustrate the Structure of the Brain and Spinal Chord in Man accurately depicted the corona radiata, cerebellar peduncles, and uncinate fascicle. In his 1842 book, The Nervous System and Its Functions , Mayo discussed the localization of higher brain functions. His dissections remained unmatched until Josef Klingler’s work in 1934. Despite the quality of his work, Mayo has been largely neglected, possibly because of his tumultuous relationship with Bell and later professional difficulties. Nevertheless, Mayo significantly contributed to white matter anatomy and led the search for cerebral localization, subsequently impacting neurosurgery. This article examines his life and work.

During his lifetime and a career spanning 42 years, James Watson Kernohan made numerous contributions to neuropathology, neurology, and neurosurgery. One of these, the phenomenon of ipsilateral, false localizing signs caused by compression of the contralateral cerebral peduncle against the tentorial edge, has widely become known as “Kernohan's notch” and continues to bear his name. The other is a grading system for gliomas from a neurosurgical viewpoint that continues to be relevant for grading of glial tumors 60 years after its introduction. In this paper, the authors analyze these two major contributions in detail within the context of Kernohan's career and explore how they contributed to the development of neurosurgical procedures.