Cranial Nerves and Related Systems

Abstract

The olfactory epithelium is located in the mucosa of the superior nasal concha, and takes up about 2.5 cm². Inside the olfactory mucosa, olfactory cells are located. They are the peripheral receptors that transmit pulses to the olfactory neurons. The latter are about 6,000,000 bipolar cells (Schulze’s cells) distributed inside the epithelium. Their dendrites group together in several filaments which constitute the true olfactory nerves; they cross the cribriform plate of the ethmoid bone and reach the olfactory bulb. The olfactory bulb is a gray matter mass, an evagination of the telencephalon, located between the gyrus rectus and the cribriform plate, containing neurons termed “mitral cells”. Their dendrites continue in the olfactory tract, which terminates with the olfactory trigone and tuberculum, in correspondence with the anterior perforated substance. Here, a group of dendrites cross the midline through the anterior commissure and join the contralateral fibers. Before ending, two striae diverge: the lateral olfactory stria, connected with the lateral olfactory nucleus and directed to the amygdaloid body, and the medial olfactory stria, directed to the septal nuclei and hypothamalus. Cortical projections of the olfactory function are identified mostly in the prepiriform and entorhinal cortex.