CRANIAL NERVES

1/19/82, 13 Jan 00, 17 Jan 01, 15 Jan 03, 28 Jan 04, 28Jan08

Martini’s 6^th, 493-506, 7^th: 480-490

On Old Olympus’ Towering Tops, A Finn and German Viewed Some Hops

   12 pairs, three carry only sensory (I, II, VIII), most mixed: contain motor and sensory

   as in spinal cord, sensory cell bodies located outside in ganglia

Overview of ventral brain: 480, spinal nerves: 493

CEREBRUM:

I 481     Olfactory      tract, not true nerve (tract: bundle of nerve fibers having same origin, function & termination.)

Actual olfactory nerves pass through cribiform plate of ethmoid receptor cells located in nasal mucosa (olfactory tract and bulb are actually part of the cerebrum)

DIENCEPHALON:

II 481     Optic               also a tract, not true nerve. Cells located in retina. Optic nerve forms chiasm.

              some fibers go to superior colliculi: visual reflexes.

              most to lateral geniculate bodies in thalamus, synapse to form optic radiations, 3°neurons lead to visual cortex

MESENCEPHALON:

III 482   oculomotor     emerge just superior to pons, supply four of six extrinsic eye muscles and upper eyelids

                         parasympathetic Ciliary ganglion associated with intrinsic muscles of eye (pupil size and lens shape).

IV 4482 Trochlear       Pulley-like muscle = superior oblique (rotates eyeball fully upward)

PONS: ( lateral)

V 483    Trigeminal: large nerve, branches into major sensory nerves of face. Sensory ganglia in huge semilunar ganglion

                          Branches:          ophthalmic:     through superior optic fissure

                                                    maxillary:        through foramen rotundum

                                                    mandibular:    through foramen ovale forms lingual nerve

VI 482   Abducens: to lateral rectus of eye

VII 484  Facial supplies            somatic motor for muscles of facial expression

                                                                 Bell’s palsy affects: caused by viral infection

sensory (taste from anterior 2/3 tongue) (gang. geniculate gang in temporal bone)

              parasympathetic:          sphenopalatine ganglion:            for lacrimal glands and nasal glands

                                                    Submandibular ganglion:            salivary glands: submandibular and sublingual

VIII 485 Vestibulocochlear: two nerves as name suggests. Entirely sensory

                          vestibular:       equilibrium, semicircular canals. Ganglia in vestibular ganglion near ear

                          cochlear:         spiral ganglion in ear: hearing

MEDULLA OBLONGATA:

IX 486   Glossopharyngeal        mixed nerve from medulla oblongata, monitors blood pressure & gasses in carotid sinus

              parasympathetic:          otic ganglion innervates parotid gland

              posterior 1/3rd of tongue, taste

X 487    Vagus:           major parasympathetic nerve. only cranial not restricted to head and neck.

                                       several rootlets fr medulla, passes through jugular foramen, passes close to carotid and jugular

                                       carries somatic to and sensory fr pharynx and larynx

              also carries sensory fr viscera, small ganglion on walls of organs: reg heart rate, depth of respiration, BP, digest, etc.

XI 489   Spinal Accessory         mixed nerve, also carries nerves arising fr upper cervical region exits by jugular foramen

      supplies muscles of larynx, pharynx, trapezius and sternocleidomastoid (along with vagus)

 XII 489 Hypoglossal Nerve:     pass thru hypoglossal canal

                                                    supplies intrinsic and extrinsic muscles of tongue as well as carries proprioceptors