The history of the olfactory nerve: from galen to primary amoebic meningoencephalitis (Naegleriasis)

The central and peripheral parts of the olfactory system serve a crucial sensory role. The olfactory epithelium and nerve fibers make up its peripheral components, while the limbic areas and olfactory bulb comprise its center structures. Galen’s historical exclusion of the olfactory nerve from his taxonomy of cranial nerves led to centuries of controversy. Its significance in sensory integration was suggested by Islamic academics such as Rhazes and Avicenna, who improved our comprehension of it. Its anatomical classification was further developed by Andreas Vesalius and Caspar Bartholin, and in the 17th century, Thomas Willis finally identified the olfactory nerve as the first cranial nerve. Recent studies have clarified its clinical relevance. SARS-CoV-2 interferes with the function of olfactory epithelium support cells, resulting in anosmia. The free-living amoeba Naegleria fowleri causes primary amebic meningoencephalitis (PAM) by getting into the brain and spinal cord through the olfactory nerve pathway. These results highlight the olfactory nerve's susceptibility to infections and its critical function in the development of illness. From prehistoric hypotheses to contemporary therapeutic uses, the history of the olfactory nerve reflects the advancement of science in general. Prevention and treatment plans for neurological disorders affecting the olfactory system are still influenced by knowledge of its anatomy and function.