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Anatomy & Physiology 120 Lab 10: Special Senses Eyes & Ears Things to know... • Be able to Identify all the following features of the eye by using: – Diagrams – Models – Preserved beef eye • Be able to Identify all the following features of the ear using – Diagrams – Models The Eye • Is hollow and spherical (~2.5 cm diameter) – Large (main) hollow space - filled with a fluid = helps maintain the eyes shape and gives support – Two spaces in the eye (Anterior cavity & Posterior cavity) • 3 layers inner, middle, outer tunic • Today we will be dissecting a cow eye (work in groups of 4 or 5) Muscles of the Eye (Extrinsic eye muscles) A) Lateral rectus Medial rectus – Opposite the Lateral rectus B) Inferior rectus Rectus - A straight muscle C) Superior rectus Oblique - Having a slanting or sloping direction D) Inferior oblique E) Superior oblique Six extrinsic eye muscles – Able to move the eye in various directions. Accessory Structures of the Eye • Eyelids – Skin, muscle, connective tissue & conjunctiva – Is the thinnest skin of the body & moved by the orbicularis oculi muscle • Conjunctiva – Mucus membrane lining the inside surface of the eyelids (folds back covering some of the eyeball) • The Lacrimal Apparatus – – – – Lacrimal gland – Makes tears Lacrimal canals (canaliculi) – Collect tears (superior & inferior) Tears then flow down and Lacrimal sac empty into the nasal cavity Nasolacrimal duct The Lacrimal Apparatus Lacrimal gland Lacrimal canals (Canaliculi) Lacrimal sac Nasolacrimal duct 8 Sclara Whites of the eye 1) Cornea – Window of the eye 2) Iris - “the color of your eyes” 3) Pupil – Where light enters the eye 4) Lens - focus light onto the retina 5) Conjunctiva - thin, transparent tissue that covers the outer surface of the visible eye & covers the eye lids 6) Retina - multi-layered sensory tissue that lines the back of the eye 7) Optic nerve - transmits electrical impulses from the retina to the brain 8) Sclera - commonly known as "the white of the eye.“ Covers the entire eye • Choroid - lies between the retina and sclera. It is composed of layers of blood vessels that nourish the back of the eye. – Ciliary body: behind the iris. Suspensory ligaments hold the lens in place – Ciliary muscle: change the shape of the lens – Iris: “the color of your eyes” thin diaphragm that controls how much light can enters you eye. Pupil: Where light enters the eye JirehDesign.com 2 Cavities of the Eye Anterior cavity – Contains Aqueous humor (watery) Posterior cavity – Contains Vitreous humor (jelly like) Retina – visual receptors (continuous with the optic nerve) Optic disk – (1) Nerve fibers leave the eye Anterior cavity “the blind spot” Posterior cavity Macula lutea – (2) In the central region of the eye Fovea centralis – (3) Region that produces the sharpest vision Optic nerve – Lead from the eyes to the brain 1 2 3 External Ear The Ear Middle Ear Auricle Auditory tube External auditory meatus Auditory ossicles Malleus Tympanic membrane Tympanic Membrane Auricle Incus Malleus Incus Stapes Semicircular canals Stapes Oval window Inner Ear 1) Cochlea 2) Semicircular Cochlea Auditory tube External auditory meatus Round window Canals The Inner Ear A complicated system of sacs and tubes filled with a fluid Bony labyrinth Membranous labyrinth • Osseous (bony) Labyrinth the outer most layer • Membranous Labyrinth the inner most layer • Vestibule (Enlarged area of the labyrinth) used to sense Static equilibrium – Utricle – Upper portion – Saccule – Lower portion Semicircular canals (balance) Ampullae- at the base of each canal where the sensory organ lies Ampulla Cochlear duct How you hear….. Hair cells Tectorial membrane (External ear) Sound waves EAM Ear drum (Middle ear) Malleus Incus Stapes Basilar Membrane * (Internal ear) The sound waves - Oval window Sclara vestibuli Vestibular membrane Tectoral membrane hair cells Excess vibrations through the basilar Membrane Sclara tympani Round window Today’s activity - Ear • Label diagrams pg 198 – 200 • Hearing tests – Rinne test #3 pg 199 (for conduction deafness) – Weber test #4 pg 200 (for sensory deafness) • Complete parts A & B Cross section of the cochlea Today’s activities - Eye • Label diagrams • Lab: Parts A (1-13 & 15) & B (the best that you can) of the lab report • Dissect the cow eye and locate features • Lab 30: Part A & B (1 & 2 only) • Do the following 5 tests – Visual acuity - Blind spot - Blind spot – Color blindness - Astigmatism Visual Tests • Visual acuity – Snellen eye chart (normal vision) – #8 – 20/20 vision (stand 20 feet away and read it) – #1 – 20/200 (stand 200 feet away and read it) • Stand 20 feet away and read the smallest line as possible (Covering one eye) **repeat & record** • Astigmatism – (defect in the curvature of the eye) – Normal eye – sees sharply focused and dark lines – Abnormal eye – some will be sharp & dark while some are not • Stand 20 ft away and focus on the center (one eye) **repeat and record** • Accommodation test – focusing for close vision – Read #3 about accommodation – Hold a meter stick against your chin / Close one eye / & move the card toward the subject – Locate the point where the subject where the word sharply focuses = near point accommodation **record & repeat** • Color vision test – (X-linked genetic) – Look at the color test plates (at least 30 inches) – Responses should occur with in 3 sec – Record the results • Blind spot – (optic nerve – no receptors) – Close one eye / Hold the card 35cm away / stare at the + / move the figure closer until the dot disappears Dissection of the Cow Eye • First - Locate the cornea, sclera and iris – The cornea from a fresh eye is white – The cornea from a preserved eye is opaque • Be careful when making the first cut (around the margin of the cornea) – Try not to damage the inside • Please read and follow the instructions!!!! • Trash all bio waste in the marked containers – No paper towels On-line Cow eye dissection www.exploratorium.edu/learning_studio /cow_eye/step01.html Nice site for Eye pics www.stlukeseye.com education.vetmed.vt.edu/.../EXAMPLES/Excorti.htm http://www.artandmedicine.com/biblio/images/rud inger/Rudinger5.jpg http://www.brainconnection.com/med/medart/l/coc hlea-xsection.jpg www.entnet.org/healthinfo/ears/ear.cfm www.freewebs.com/.../creatoroftheringsandof.htm http://www.unmc.edu/eye/Media/retina.jpg www.99main.com/~charlief/Blindness.htm http://utopia.duth.gr/~adamand/destruction/ima ges/eye.jpg www.discovery.com/.../skinny1.html