Ten pairs of cranial nerves arise from the brain at different locations to supply the anterior region of the body. In addition to them a pair of terminal or pre olfactory nerves (zero nerves) arises from the ventral surface of the cerebrum. The ten pairs of cranial nerves are furnished below for detail study. Name of the nerve Origin Branches Distribution Physiological Nature 1. OLFACTORY Olfactory lobe. - Olfactory epithelium of the nasal cavity. Sensory 2. OPTIC Optic lobe. - Retina of eye. Sensory 3. OCULOMOTOR Ventrolateral side ofthe midbrain. - Anterior rectus, superior rectus, inferior rectus and inferior oblique muscles of the eye. Superior oblique muscle of the eye Motor Motor 4. TROCHLEAR Dorsolateral aspect of the midbrain between the optic lobes and cerebrum. - Olfactory capsule and dorsal Mixed 5. TRIGEMINAL Dorsally from the side of medulla oblongata below the corpora restiformes. (i) Opthalmic profundus (ii) Ophthalmicus superfi-cialis V (iii) Maxillaris V (a) Superior (b) Inferior (iv) Mandibularis skin of the snout. Skin of the snout. Skin of upper jaw Posterior part of upper lip. Muscles of the lower jaw. Mixed Motor Mixed 6. ABDUCENS Midventrally from the floor of medulla oblongata - Posterior rectus muscle of the eye. Mixed 7. FACIAL From the side of medulla below the corpora restiformes in the form of a bundle. (i) Opthalmicus super-ficialis VII (ii) Ramus buccalis (iii) Flyomandibularis (a) Mandibularis externus (b) Mandibularis internus (c) Hyoidean (iv) Ramus palatinus Sense organs; the lateral line system of snout. Infra-orbital lateral line canal and associated ampullae. Mandibular canal of lateral-line system. Mucous membrane of the floor of buccal cavity. Muscles of the roof of buccal cavity and pharynx. Roof of the pharyngeal and buccal cavity. Mixed Mixed Mixed Mixed Mixed Sensory 8. AUDITORY From the side of medulla close to the V and Vll cranial nerves. (i) Vestibular (ii) Saccular Membranous labyrinth of the internal ear Sensory 9. GLOSSOPHARYN GEAL From the ventro-lateral side of medulla. (i) Pre-trematic (ii) Post-trematic Mucous membrane of the first gill-cleft and the pharynx. The muscles of the pharynx Gills. Sensory Mixed Mixed 10. VAGUS Side of Medulla. (a) Branchialis (b) Visceralis (c) Lateralis Viscera. Lateral-line system of the trunk. Mixed Mixed Mixed