Class Notes (834,037)
Canada (508,290)
Brock University (12,083)
Biology (1,621)
BIOL 2P95 (35)
Lecture

Nerves Lectures I and II

10 Pages
121 Views
Unlock Document

Department
Biology
Course
BIOL 2P95
Professor
Dirk De Clercq
Semester
Fall

Description
Cranial Nerves Lectures I and II CN I = olfactory • Special sensory nerve of smell • Olfactory nerve = bundle of nerves, located in upper nasal mucosa o 25 million olfactory cells on each side of mucosa o bipolar neuron cells: their deep processes merge to make plexiform network o plexiform network then recombine to give bundles of nerve that give olfactory nerve, proper • Nerves come through cribriform (=sieve like) plate: piece of ethmoid bone o Ethmoid bone: thin, complex bone between orbits o In middle of cribriform plate: cristae galae: where falx cerebri attaches in front o Holes in cribriform plate: where nerves are transmitted into end of anterior portion of endocranial fossa • Nerves are attached to olfactory bulbs, which are then joined to olfactory tracts o Bundles of nerve travel through cribriform to olfactory bulbs where they synapse @ mitral cellsolfactory tracts o Olfactory tracts connected to telencephalon o Olfactory bulbs can break  lost of smell (anosmia) o Olfactory cells: degenerate at 1% a year; regenerate CN II: optic • Special sensory nerve of vision • Nerve begins in retina in back of eyeball o Retina: developmentally is an outgrowth of brain o Retina converges at optic disk to become continuous with optic nerve o Optic nerve is surrounded by meninges because of connexn with retina o Each optic nerve: million of ganglion cells  Ganglion cells synapse at bipolar cells  Bipolar cells lengthen to form rods and cones • Nerve travels through optic canals: oblique openings o Optic canals open at junction between anterior middle cranial fossae • Two optic nerves meet to form optic chiasma: in front of pituitary o Nerve fibers from medial half of retina cross in optic chiasma o Lateral fibers stay on the same side o Effect: carry neurons in related visual field end up in same optic tract o The fibers go back to the thalamus or midbrain (lateral geniculate ganglion or superior colliculi ganglion) CN III: oculomotor o Comes off of midbrain and goes under the lesser wing of sphenoid o Goes through superior orbital fissure: opens into back of orbit o Nerve is lateral to optic nerve o Associated with all muscles of the eye: both smooth and striated o General somatic motor and parasympathetic component o General somatic motor o Supply most (5 out of 7) of the muscles around eyeball that move it o Nerve splits immediately after exit o Superior division:  Superior rectus: moves eyeball  Levator palpebrae superioris: elevator of upper eyelid o Inferior division  Medial and inferior rectus  Inferior oblique  Three extraocular muscles move eyeball o Parasympathetic: third division of CN III o Synapse in ciliary ganglion on way to eye  Postganglion parasympathetics carried in short ciliary nerves o Ciliary nerves fibers pierce eyeball and travel to front to supply two smooth muscles  Pierce sclera and travel between outer and middle coat  Sphincter pupillae: in the iris, controls size of pupil (amount of light)  Ciliary muscle: surrounds the lens, allows up-close focus o Nasociliary nerve from trigeminal suspends ciliary ganglion but does not synapse o All 4 parasymp ganglion suspended by a fiber from trigeminal nerve CN IV: trochlear o Smallest CN o Comes off back of back of midbrain o Passes on side of middle cranial fossa o Exits through superior orbital fissure to travel in medial roof of orbit o Somatic motor nerve to superior oblique muscle that moves the eye o Superior oblique muscle: o Changes direction of pull within the orbit by passing through a fibrocartilage loop in superomedial angle of orbit= trochlea o Origin: apex of orbit o Insertion: above eyeball o Muscles courses along upper medial angle of orbit CN V: trigeminal o Largest cranial nerve o Emerges from pons and goes thru middle cranial fossa o Forms huge semilunar/trigeminal sensory ganglion (medial side of middle cranial fossa) and divides into 3 pieces o Primary somatic sensory nerve of head; also a motor nerve of first pharyngeal arch 1, 2, 3 o Labelin1 scheme: CN V o CN V = ophthalmic, entirely sensory o Goes to superior orbital fissure to join CN III and IV to go to back of orbit o Supplies cornea, conjunctiva, eyeball, lacrimal gland, forehead, nose, upper eyelid, frontal and ethmoid sinuses o Emerges in forehead from frontalis o Branches  Lacrimal: small, lateral • provides somatic sensory to lacrimal gland, adjacent eyelid and conjuncitva (doesn’t control secretions)  Frontal (supraorbital, supratrochlear): both travel to upper medial corner of eye through foramen • Terminal branches on forehead: sensory  Nasociliary • Under levator palpebrae superioris and superior rectus • Four branches o Suspends ciliary ganglion with sensory root: see above  Fibers are considered part of short ciliary nerves  Short ciliary • Parasympathetic • To back of eyeball, pierce sclera and travel on eyeball • May contain some sympathetic fibers o Long ciliary nerves:  Follows same course as short ciliary  Sensory to eye  Primary carrier of sympathetics to ciliary body, iris • dilate muscles Side note: sympathetics travel in sympathetic trunk into neck where there are 3 cervical ganglion • superior cerv. Ganglion o base of skull, above of carotids o where sympathetics of head will synapse o fibers form plexuses around internal and external carotid o fibers can come up with internal carotid and contribute to CNs o Ethmoidal and nasal: from ethmoidal and sphenoidal sinuses, nasal cavity and front and tip of nose  pierces medial wall of orbit  Supplies mucosa  Pierces forward to supply nasal cavity: nasal nerves o Infratrochlear: from superomedial corner of orbit below trochlea  Just sensory o CN V =maxillary, entirely sensory o Goes thru foramen rotundum (a round hole behind the medial angle of the superior orbital fissure, that goes forward in skull) o Takes a bent course to go to floor of orbit; travels the infraorbital fissure and thru infraorbital canal and out the infraorbital foramen o Sensory innervation of cheek; sensory for everything from floor of orbit to roof of mouth  Upper jaw, maxillary sinus, nasal cavity, middle of face, middle ear cavity, auditory tube and dura o Branches  Supends pteryogopalantine ganglion (CN VII) • To reach ganglion, travels vertically along pteryogomaxillary canal • Fibers pass thru then go medially along nasal cavity to palate  Zygomatic: from cheek • Sends sensory thru lateral wall of orbit onto cheek  Nasal branches: from mucous membranes of nasal sinuses  Palatine branches (lesser, greater, nasopalatine) • Fibers pass through pteryogpalatine ganglion • Descend through palatine canal and exit respective foramen • Sensory nerves to palate  nasopalatine nerve • supplies nasal septum • goes to front of palate and exits out opening behind upper incisors (incisor foramen) • sensory to front of palate  Superior alveolar branches from upper teeth, gums, maxillary sinus • Maxillary sinus: hollow cavity from floor of orbit to roof of mouth; lined with mucosa  infraorbital: terminal branch  sensory between orbit and mouth  meningeal: from middle and anterior cranial fossae • given off before exiting foramen rotundum • supplies dura around area  pharyngeal: passes thru ganglion • from middle ear cavity and auditory tube • upper part of pharynx (back of throat) • connection to middle ear o CN V = mandibular, sensory and motor o Largest division o Exits skull thru foramen ovale (postero lateral from foramen rotundum; oval opening); exits at lower jaw o Supplies sensory to lower jaw (tongue, lower teeth, chin, cheek, floor of mouth, anterior 2/3 of tongue, tympanic membrane, salivary glands) o Also supplies motor innervation for mastication  Branchiomotor: associated with first branchial/pharyngeal arch  Striated muscles are supplied  Branches to muscles of mastication • Temporalis, masseter, medial and lateral pterygoids  Branches to floor of mouth: mylohyoid, digastric (anterior belly), tensor veli palatine (tenses roof of palate) and tensor tympani (tenses ear drum) o Branches after motor branches  Buccal • Sensory from cheek, internal and external • Pierces buccinator to mucus membranes and skin  Auriculotemporal • Sensory from external acoustic meatus and tympanic membrane, temporal region and temperomandibular junction • Suspends otic ganglion (CN IX)  Lingual • Sensory for anterior 2/3 of tongue, floor mouth, mandibular gums • Joined by piece of chorda tympani of facial nerve • Suspends submandibular ganglion (CN VII)  Inferior a
More Less

Related notes for BIOL 2P95

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit