Chapter contents Overview Olfactory epithelium Sensory transduction & Peripheral course Central course Rhinencephalon Major projections

Cranial Nerve I - Olfactory Nerve Page 4 of 6 Central course of the olfactory tract The olfactory bulb, which contains the cell bodies of the secondary sensory neurons, is an enlargement of the rostral end of the olfactory tract. The olfactory tract consists of the axons of these secondary sensory neurons. Just rostral to the anterior perforated substance the olfactory tract divides into the lateral, intermediate, and medial striae at the olfactory trigone. The axons of the olfactory tract project to the lateral (primary), intermediate, and medial (secondary) olfactory areas of the cortex via these striae. There are two principal types of secondary sensory neurons: Mitral cells - project primarily to the lateral (primary) olfactory area of the rhinencephalon. These neurons also give off collateral fibers to the anterior olfactory nucleus. Tufted cells - project to the anterior olfactory nucleus and to the lateral, intermediate and medial olfactory areas of the rhinencephalon. Postsynaptic fibers from the anterior olfactory nucleus project along with the mitral and tufted cell axons to the rhinencephalon or via the anterior commisure to the contralateral anterior olfactory nucleus. Figure 1-4. Central course of the olfactory tract.

Last revised: March 22, 1998