Introduction Enlarged parietal foramina are variable ossification defects in the parietal bones that present as symmetric radiolucencies on skull radiographs. In contrast to the normal small parietal foramina, enlarged parietal foramina are a hereditary condition and genes associated with it have been identified. Methods A literature review was performed to discuss the many known findings related to enlarged parietal foramina. Conclusions Even though they remain asymptomatic in the majority of cases, they may be associated with other pathologies and occasionally become symptomatic. This article provides a comprehensive review of the current knowledge of enlarged parietal foramina.

Objectives?The trochlear nerve is important to preserve during approaches to the skull base. Traditionally, this nerve has been divided into cisternal, cavernous, and orbital segments. However, the authors anecdotally observed an additional segment during routine cadaveric dissections. Therefore, they performed this study to better elucidate this anatomy. Design?Twenty latex-injected cadaveric sides (10 adult cadavers) were dissected with the aid of an operating microscope. Standard microdissection techniques were used to examine the course of the distal cisternal and precavernous segments of the trochlear nerve. Setting?Cadaver laboratory. Main Outcome Measures?Measurements were made using a microcaliper. Digital images were made of the dissections. Results?The authors identified a previously undescribed segment of the trochlear nerve in all specimens. This part of the nerve coursed between the entrance of the trochlear nerve into the posterior corner of the oculomotor trigone to the posterior wall of the cavernous sinus. This segment of trochlear nerve was, on average, 4?mm in length. Conclusions?The authors have identified a new segment of the trochlear nerve not previously described. They propose that this be referred to as the trigonal segment. Knowledge of the microanatomy of the trochlear nerve is useful to skull base surgeons.

Humphrey Ridley is a little known character in the history of anatomy and physiology. Born in 1653, Ridley was a physician and anatomist who followed the research done by Willis, Vieussens, and Galen. Outside of a cursory knowledge of his birth and death, readers have only two remnants of his contributions to science: The Anatomy of the Brain, containing its Mechanism and Physiology and Observationes Quaedam Medico-Practicae et Physiologicae de Asthmate et Hydrophobia. The former text was the first book in the English language written on the human brain. Ridley's studies using cadavers executed by hanging provided him with a novel view of the venous drainage and lymphatic system not seen as accurately by those before him. Since the study of the brain was still largely in its infancy, he was not without his errors of deduction as to the purpose of parts of the brain and its pathologies. With his dissections, however, Ridley was able to build on the collective knowledge of neuroanatomy and provided new insight into brain structure and function. The current paper reviews what is known of Ridley's life and contributions to neuroanatomy and neurophysiology.