Cranial Nerves: I & II

1. Cranial Nerves: I & II I. Olfactory-- sensory (smell) • nerves embedded in nasal mucosa • enter cranial cavity through olfactory foraminain cribriform plate (ethmoid bone) • synapse with other neurons in olfactory bulb impulse continues through olfactory tract II. Optic-- sensory (sight) • nerves extend from retina • enter cranial cavity through optic foramina(sphenoid bone) • medial fibers cross at optic chiasma (sits in chiasmatic groove of sphenoid bone) • fibers continue as optic tracts Illustration

2. Olfactory Nerve (I) – contain the sensory nerves of smell

4. Optic Nerve (II) – sensory nerve of vision

5. Visual Fields of the Eyes Fig. 16.12, p. 584

6. Cranial Nerves: III & IV III. Oculomotor – motor • extrinsic muscles of eye except lateral rectus and superior oblique (eye movement) • intrinsic smooth muscle of iris (constriction in response to brightness) and lens (controls shape for focusing) IV. Trochlear – motor • superior oblique muscle of eye Illustration

7. Oculomotor Nerve (III) – “eye mover” innervates muscles that supply the eyeball

9. Trochlear Nerve (IV) – means “pulley” it innervates an extrinsic eye muscle that loops through a pulley-shaped ligament

10. Cranial Nerves: V V. Trigeminal– mixed;largest cranial nerve, major sensory nerve serving face (skin, mucosae of mouth, surface of eyes), also important motor nerve (chewing) • mandibular division – motor to chewing muscles; sensory from anterior tongue and lower teeth • mandibular division exits/enters through foramen ovale • ophthalmic and maxillary divisions -- sensory • ophthalmic division from area around eye and forehead enters through superior orbital fissure • maxillary division from area around nose, cheeks, upper jaw enters through foramen rotundum Illustration

11. Trigeminal Nerve (V) – supplies sensory information to the face and chewing muscles

12. Cranial Nerves: VI & VII VI. Abducens– motor • lateral rectus muscle of eye • enters/exits cranial cavity through superior orbital fissure VII. Facial – mixed • sensory from taste buds on tongue • motor (ANS) to salivary and lacrimal glands • motor (somatic) to muscles of facial expression • enters/exits through stylomastoid foramen Illustration

13. Abducens (VI) – controls the extrinsic eye muscles that abduct (turn it laterally) the eyeball

14. Facial Nerve (VII) – a large nerve that innervates muscles of facial expression

15. Cranial Nerves: VIII & IX VIII.Vestibulocochlear – sensory • hearing and balance from inner ear • enters through internal acoustic meatus IX. Glossopharyngeal -- mixed • motor to pharyngeal muscles and salivary glands • sensory from taste buds • exits/enters through jugular foramen (border of temporal and occipital bones) Illustration

16. Vestibulococlear Nerve (VIII) – two branches one for hearing, one for balance

17. Glossopharangeal (IX) – name means “tongue and pharynx” innervates the tongue and pharynx

18. Cranial Nerves: X X. Vagus-- mixed • motor (somatic) to pharynx and larynx for swallowing and speaking • motor(ANS:parasympathetic) innervation to heart, lungs and abdominal viscera • sensory info from thoracic and abdominal viscera • exits/enters through jugular foramen (border of temporal and occipital bones) Illustration

19. Vagus (X) – name means “wanderer” only cranial nerve to extend beyond the head

20. Cranial Nerves: XI & XII XI. Accessory-- motor • muscles of neck • enters/exits through jugular foramen (border of temporal and occipital bones) XII. Hypoglossal– motor • muscles of tongue (chewing, swallowing and speech) • enters/exits through hypoglossal canal (superior to occipital condyles of occipital bone) Illustration

21. Accessory Nerve (XI) – joins to help the vagus nerve, innervates neck musculature

22. Hypoglossal (XII) – innervates some tongue- moving muscles

24. Cranial Nerves: I - XII Fig. 13.4, p. 484