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Week 10 Lecture Notes - Principles of Human Anatomy

by: Victoria Dorsey

Week 10 Lecture Notes - Principles of Human Anatomy Bio 103, Principles of human Anatomy

Marketplace > University of Indianapolis > Biology > Bio 103, Principles of human Anatomy > Week 10 Lecture Notes Principles of Human Anatomy
Victoria Dorsey
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The two topics were about the the cranial nerves and the special senses of the eyes and ears.
Principles of human anatomy
Justin Maiers
Class Notes
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This 11 page Class Notes was uploaded by Victoria Dorsey on Friday November 13, 2015. The Class Notes belongs to Bio 103, Principles of human Anatomy at University of Indianapolis taught by Justin Maiers in Fall 2015. Since its upload, it has received 20 views. For similar materials see Principles of human anatomy in Biology at University of Indianapolis.

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Date Created: 11/13/15
Principles of Human Anatomy BIOL 103-05 02 November 2015 Cranial Nerves Peripheral Nervous System (PNS)  Provides links from and to outside body  All neural structures outside brain o Sensory receptors o Peripheral nerves and associated ganglia o Efferent motor endings  Nerves for the 5 senses leave the brain hence PNS Types of Nerves  Sensory (afferent) nerves carry impulses towards CNS  Motor (efferent) nerves carry impulses away from CNS o Active control  Mixed nerves contain both sensory and motor fibers and transmit impulses both to and from the CNS o Most nerves are mixed Sensory (Mechano) Receptors  Mechanical force (touch, pressure, vibration, stretch)  Temperature  Light (retina)—distinguish between colors and shades  Chemicals [smell, tastes, changes in blood chemistry (can tell the amount of insulin in the bloodstream)]  Pain (immediate movement) Cranial Nerves  Attach to the brain and pass through foramina of the skull  Numbered I-XII  Cranial nerves I and II attach to the forebrain (left and right hemispheres)—optic and olfactory o All others attach to the brain stem  Primarily serve head and neck structures o Except: the vagus nerves (X) extend into the abdomen—controls lungs and heart  Mnemonic delivered at the end  All in roman numerals Olfactory Nerve, CN I Sensory  Special sensory of smell  Extends outside of the brain  Perforates the ethmoid bone  Damage here results in—Anosmia: reduction or loss of ability to smell  Olfactory blubs rest on top of the cribriform plate of the ethmoid Optic Nerve, CN II Sensory  Special sensory nerve of vision  Anopsias: visual defects  Only need to know that this is the rods and cones of the eye  Retina attaches here  Retina -> optic nerve -> cross at chiasma -> optic tracts -> thalamus -> occipital lobe  Don’t have to remember pathways  Crossed paths help with depth perception Oculomotor Nerve, CN III Motor  “Eye mover” – somatic motor function  Innervates eye muscles: o Inferior oblique o Superior rectus o Inferior rectus o Medial rectus  Raises upper eyelid  Constricts pupil  Primary mover of the eye  Has motor in the name and makes knowing the function pretty easy  Don’t worry about the muscles because we will talk about them more once we get into special senses  Midbrain -> oculomotor nerve -> bony orbit -> eye muscles  Goes through orbital fissure  Damage to this causes: o No up, down, or inward movement o Droopy eyelid (ptosis) o Double vision—eye drifts and does not focus on the same item Trochlear Nerve, CN IV Motor  Somatic motor  Only CN to come off back of brain stem  Innervates superior oblique eye muscle  Helps stabilize the motion of the eye as the body sways when you walk/move  Midbrain -> bony orbit -> eye muscle  Damage to this causes: o Double vision o Can’t rotate eye inferolaterally Trigeminal Nerve, CN V Mixed  Sensory from face, eyes, teeth, gums, sinuses, lips, and anterior 2/3 of tongue  Motor to masticatory muscles  Largest cranial nerve  3 branches/regions: o Mandibular o Maxillary o Opthalmic (everything in the forehead and eye region)  Some sensation and some for motor  Sensation for the majority of the face  Damage to this causes: o Trigeminal neuralgia: intense pain of the jaw or face  Whole face feels like it is on fire  The nerves are inflamed, but not actually broken  Novocain injections can be used to dull the nerves and fight the pain Abducens Nerve, CN VI Motor  Somatic motor  Innervates lateral rectus muscles  Abducts the eyeball  Pons -> bony orbit -> eye muscle  Damage to this causes: o No lateral eye movement Facial Nerve, CN VII Mixed  Somatic motor to muscles of facial expression  Visceral motor to salivary and lacrimal glands (autonomic/uncontrolled)  Sensory—taste from anterior 2/3 of tongue and soft palate  5 branches of the facial nerve: o Temporal o Zygomatic o Buccal o Mandibular o Cervical—down to platysma muscle  Branches named for where they are going and what they are doing  Damage to this causes: o Bell’s Palsy—paralysis of the facial muscles, partial loss of taste, droopy eyelids and mouth, and constant tearing  Can be damaged in a small section or as a whole  Tends to impact one side of the face and causes paralysis of half of the face Vestibulocochlear Nerve, CN VIII Sensory  Special sensory nerve of hearing and balance  Cochlear branch  Vestibular branch  To the parts of the ear  For hearing and balance  More on this when we talk about special senses  Cochlea—hearing  Vestibule—balance  Inner ear -> internal auditory meatus -> pons/medulla border  Damage to this causes: o Cochlear division: deafness o Vestibular division: problems with balance and equilibrium Glossopharyngeal Nerve, CN IX Mixed  Visceral motor to parotid gland (autonomic) o Parotid gland helps create saliva (motor)  Sensory from pharynx and post 1/3 of tongue o Taste from post 1/3 of tongue  Medulla -> jugular foramen -> throat  Damage to this causes: o Problems with taste and swallowing  This nerve is important for gag reflex o If the gag reflex is not there, you could choke Vagus Nerve, CN X Mixed  Somatic motor to muscles of pharynx and larynx (swallowing and vocalization)  Visceral motor to muscles of gut, heart, and lungs  Visceral sensory from organs  Only nerve to come out of the head and neck region  Does more rhythm things; does not need a thick nerve  Senses rate of heart beating, how fast the body is processing food, and breathing rates  Medulla -> jugular foramen -> neck -> thorax -> abdomen  Damage to this causes: o Damage: partial or complete loss of voice and digestive tract o Total destruction: death  Complete destruction means no heartbeat, no breathing, and no food digestion Accessory Nerve, CN XI Motor  Somatic motor  Helps the vagus nerve  Motor to the sternocleidomastoid and trapezius  Formed by the union of a cranial and spinal nerve o Only nerve that pulls from both the head and the spine  Runs with the vagus nerve o Only runs to the neck and does not go to the organs of the body  Damage to this results in: o Paralysis of sternocleidomastoid and trapezius Hypoglossal Nerve, CN XII Motor  Somatic motor  Runs inferior to the tongue  Motor to tongue muscles  Does not account for taste or sensation of the tongue  Only motor movement of the tongue  Medulla -> tongue  Damages to this result in: o Problems with speech and swallowing Mnemonics Remembering the Nerves 1. Olfactory 2. Optic 3. Oculomotor Offensive oranges 4. Trochlear 5. Trigeminal of Tibet traded 6. Abducens apples for Van 7. Facial 8. Vestibulocochlear Gogh’s very angry 9. Glossopharyngeal 10. Vagus hippo 11. Accessory 12. Hypoglossal Remembering the Function of the Nerve 1. Sensory 2. Sensory 3. Motor 4. Motor 5. Both Some say money 6. Motor 7. Both matters but my 8. Sensory brother says big 9. Both brains matter most 10. Both 11. Motor 12. Motor Principles of Human Anatomy BIOL 103-05 04 November 2015 Eye and Ear Special Senses  Special sensory receptors o Distinct, localized receptor cells in head o Not really talking about taste and smell  Vision  Taste  Smell  Hearing  Equilibrium The Eye The things you should be able to do by the end of this section: 1. Understand the functions of the eye 2. Identify the covering layers of the eye 3. Name the internal structures of the eye 4. Same the 6 muscles for motion of the eye The Eye and Vision  70% of the body’s sensory receptors are dedicated to the eye  Visual processing takes up half of the cerebral cortex  Most of the eye is protected by a cushion of fat and body orbit Accessory Structures of the Eye  Protect the eye and aid eye function o Eyebrows  Overlie supraorbital margins  Function:  Shade from sunlight  Prevent perspiration from reaching eye  Facial expression o Eyelids (palpebrae)  Muscle: levator palpebrae superioris  Gives upper eyelid mobility  Bling reflexively every 3-7 seconds  Protection  Spreads secretions to moisten eye o Keeps eye clean  Ptosis (Forrest Whitaker Eye)  Cause: damage to a branch of CN III or poor muscle development of levator palpibrae  Droopy eyelid o Conjunctiva  Most superficial layer of the eye  Clear, vascular layer over sclera (white)  Used for lubrication and protection from outside environment  Covers the whole eye  Blood vessels lay in this layer  Conjunctivitis = pink eye  -itis means “inflammation” or “irritation”  Draws more blood supply as it tries to heal and fight off infection o Lacrimal apparatus  Lacrimal gland and ducts that drain into nasal cavity  Lacrimal gland in orbital above lateral end of eye  Lacrimal secretion (tears)  Drain into lacrimal sac and nasolacrimal duct o Extrinsic eye muscles  Six straplike extrinsic eye muscles  Originate form body orbit; insert on eyeball  Enable eye to follow moving objects; maintain shape of eyeball; hold in orbit  Four rectus muscles originate from common tendinous ring; names indicate movements  Superior, inferior, lateral, and medial rectus  Rectus muscles pull straight in one direction, up/down/left/right  Two oblique muscles move eye in vertical plane and rotate eyeball  Superior and inferior oblique muscles  For the rotation of the eye  Inferior oblique is the only one that does not originate from the same point as all the other eye muscles  Trochlea redirects which way the superior oblique muscle is going  Movement is mostly done by the oculomotor nerve Sclera and Cornea  The two fibrous outer layers of the eye that provide shape and support to deep structures  Sclera = white of the eye o Attachment site of muscles o Continuous with the dura mater of the brain o Makes up approximately 85% of the eye surface  Cornea covers the pupil and iris -> clear so light can pass through o Convex so the light can focus o Lots of nerve endings so it makes you blink or your eyes water to clear out dirt The Iris  Pigment layer o Single-cell-thick lining o Absorbs light and prevents its scattering o Stores vitamin A o Very thin layer that protects the eye form how much light is being taken in  Muscles of the Iris o Pupillary constrictor  Parasympathetic  Contracts in a circles when there is an overabundance of light  Pupil size decreases o Pupillary dilator  Dilates in a straight line  Kind of sympathetic because if you see something that you want or get really excited, it will dilate Internal Structures of the Eye  Lens—clear disc that can change shape to focus light o Focuses light at different distances  Ciliary bodies—muscles that control shape of lens  Choroid—dark pigmented layer used to attract light o White blocks out light o Black on the inside of the eye draws in the light and keeps it in so that you can see  Fovea centralis—point where the eye best focuses o Has the most nerve endings and point for best focuses o Dipped in so that there is more surface area so that you can see more  Optic disc—blind spot where optic nerve leaves the eye o Exact opposites  Neural Layer—contains photoreceptors o Rods and cones o See color o Innermost layer of the eyeInternal Cavities and Chambers  Eye can be divided into two separate cavities o Anterior and posterior cavities o Anterior Cavity is made up of the Anterior chamber and Posterior Chamber  Separates into functional parts  Anterior Cavity o Aqueous humor  Supplies nutrients and oxygen mainly to lens and cornea but also to retina, removes wastes o Two chambers  Anterior Chamber—between cornea and iris  Posterior chamber—between iris and lens  Posterior Cavity o Vitreous humor  Transmits light  Supports posterior surface of lens  Contributes to intraocular pressure  Forms in embryo; lasts lifetime  Keeps the eye inflated  Everything behind lens  Aqueous is in anterior chamber because A comes before V in the alphabet Cataracts  Clouding of lens o Consequence of again, diabetes mellitus, heavy smoking, frequent exposure to intense sunlight o Some congenital (related to the condition at birth/genetic) o Crystalline proteins clump o Vitamin C increases cataract formation o Lens can be replaced surgically with an artificial lens o Is like looking through wax paper  Essentially the lens of your eye is getting a sunburn The Ear By the end of this section, you should be able to: 1. Understand the 3 divisions of the ear 2. Identify the structures of the middle ear 3. Understand the structures of the inner ear Divisions of the Ear  External Ear  Middle Ear  Internal Ear Hearing and Balance  External (outer) ear—focuses sound o Brings sound from the outside into the ear o Acts as a sonar  Middle ear (tympanic cavity)—hearing only o Starts to send signals to hearing senses  Internal (inner) ear—hearing and equilibrium o Receptors for hearing and balance respond to separate stimuli o Are activated independently o Part for hearing and the rest is for equilibrium External Ear  Auricle (pinna) o Composed of:  Helix (rim)  Lobule (earlobe) o Funnels sound waves into auditory canal  External acoustic meatus (auditory canal) o Short, curved tube lined with skin bearing hairs, sebaceous glands, and ceruminous glands o Transmits sound waves to eardrum  Tympanic Membrane (eardrum) o Boundary between external and middle ears o Connective tissue membrane that vibrates in response to sound  Reverberates when sound hits it o Transfers sound energy to bones of middle ear  Sends essentially Morse code through the bones Middle Ear (Tympanic Cavity)  Flanked laterally by eardrum  Flanked medially by bony wall containing oval (vestibular) and round (cochlear) windows  Eustachian tube—connects middle ear to nasopharynx o Equalizes pressure in the middle ear cavity with external air pressure  Keeps the pressure even o Doctors focused on ear, nose, and throat are actually focused on the Eustachian tube  Ear Ossicles—three small bones in tympanic cavity: the malleus, incus, and stapes o Suspended by ligaments and joined by synovial joints o Transmit vibratory motion of eardrum to oval window o Tensor tympani and stapedius muscles contract reflexively in response to loud sounds to prevent damage to hearing receptors  Don’t worry about the muscles themselves  The small muscles pull everything away from each other so that it doesn’t hit the tympanic membrane so hard Two Major Divisions of the Inner Ear  Bony labyrinth—makes up most of the inner ear o Tortuous channels in temporal bone o Three regions: vestibule, semicircular canals, and cochlea o Filled with perilymph (similar to CSF)  Membranous labyrinth—completely encased in bone o Series of membranous sacs and ducts o Filled with potassium-rich endolymph o For fluid and nutrient supply  Vestibule—central egg-shaped cavity of bony labyrinth o Contains two membranous sacs  Saccule—is continuous with cochlear duct  Utricle—is continuous with semicircular canals o These sacs  House equilibrium receptor regions (maculae)  Respond to gravity and changes in position of the head  Semicircular Canals o Used for balance equilibrium o Three canals (anterior, lateral, and posterior) each define 2/3 of circle  All on different planes so they can sense motion in a 3 dimensional plane  Proprioception o Communicate with utricle o Ampulla of each canal houses equilibrium receptor region called crista ampullaris  No way to tag the crista ampullaris on the practical because it is encased in bone  Crista ampullaris is mostly fluid filled  Crista ampullaris (in ampulla) o Receptors respond to angular (rotational) movements of the head  Maculae—respond to gravity and acceleration o In Utricle = horizontal acceleration o In Saccule = vertical acceleration Vertigo o Damage to the vestibular portion of CN VII o Inability to tell the difference between what you are seeing and what you are feeling The Cochlea o A spiral, conical, bony chamber o Size of a split pea o Extends from vestibule o Coils around bony pillar (modiolus) o Contains cochlear duct, which houses spiral organ (organ of Corti) and ends at cochlear apex o Organ of Corti = hearing o You hear different frequencies with different parts of the cochlea


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