Cranial Nerve 0 (Terminal Nerve)
Definition
-Collection of microscopic nerve fibers found on the ventral surface of the frontal lobe, close to the olfactory tract
Discovery
-1st described by Felix Pinkus (1913)
Anatomical Course
-Originates from neurons in the nasal mucosa
-Fibers pass through the cribriform plate
-Terminate in areas of the forebrain, especially the hypothalamus and septal nuclei
Functions
-Pheromone detection, sexual behavior
>Terminal nerve provides a direct pathway between nasal cavity & hypothalamic reproductive centers, bypassing classical olfactory circuits
-Reproductive, neurons related to GnRH
-Modulation of autonomic & limbic activity
Clinical Significance
-Developmentally related to migration of GnRH neurons
>Abnormality may lead Kallmann syndrome
Why It Is Called “Cranial Nerve Zero”
-Lies ant to CN I
Important Characteristics
-Very thin and microscopic
-Present in humans and many vertebrates
-Often not visible in routine gross dissection