Special Senses Ears Chapter 15 Objectives: O Identify the primary functions of the Ear O Introduce some medical words related to the Ear O Identify and define some selected abbreviations related to the Ear Ear: O One who specializes in the study of hearing is : O Audiologist Ear: O The ear is the organ that detects sound O It also helps provide balance and equilibrium O consists of outer, middle, and inner parts External (outer) ear: O is the most external portion of the ear O consists of the visible portion on the side of the head, known as the pinna and the external auditory canal or ear canal. Contd: O Pinna: (also called the auricle) the visible part of the outer ear. It collects sound and directs it into the outer ear canal O External ear canal: the tube through which sound travels to the eardrum. (tympanic membrane) Contd: O The ear drum is about 1 ¼ inches long O Contains modified sweat glands O Sweat glands secrete Cerumen (Latin word for ear wax) O Too much Cerumen can block sound transmission Word Building: O Auricle O Aur/i O -cle ear small thing O Pinna O Latin word meaning wing or fin Contd: O O O O anacusis anwithout, absence of -acusis hearing condition Total hearing loss O O O O otalgia ot/ ear -algia pain Pain in the ear, earache Middle Ear: O located between the outer ear and the inner ear and consists of the following parts : O Eardrum - The eardrum, also known as tympanic membrane is a thin membrane that acts as a partition between the outer ear and the middle ear. O Has three small bones or ossicles that are important for hearing. Contd: O Hammer (Malleus) - It is a tiny bone, located next to the eardrum. Since it lies adjacent to the eardrum, the vibrations from the eardrum cause the hammer to vibrate. O Anvil (Incus) - Anvil is another tiny bone next to hammer; it vibrates in response to the vibration of hammer. O Stirrup (Stapes) - Similar to hammer and anvil, stirrup is a tiny bone in the middle ear; eventually, it also vibrates and passes the compressional waves to the inner ear. Inner Ear: O is the innermost portion of the ear. O It is filled with a water-like substance and comprises both hearing and balancing organs. O Consists of a maze like network of canals located within a bony labyrinth O The bony labyrinth comprises the following parts: Contd: O Cochlea - or the spiral tube is a rolled structure that can stretch to about 3 cm; O the membrane lining of cochlea consists of numerous nerve cells. The hair-like nerve cells respond differently to various frequencies of vibrations, which ultimately lead to generation of electrical impulses. O Semicircular Canals - These are fluid-filled loops, attached to the cochlea and helps in maintaining the balance. O Auditory Nerve - The electrical impulses, generated by the nerve cells, are then passed to the brain Process of Hearing: O Outer Ear - captures sound waves and guides them into the ear canal O Ear Canal - carries the sound waves towards the eardrum O Eardrum - (tympanic membrane) vibrates from the sound waves O Middle Ear Bones - (malleus, incus and stapes) pick up vibration from the eardrum O Cochlea - as vibrations pass through this organ, the fluid inside the cochlea moves, causing thousands of "hair cells" to set in motion so they can translate the sound waves into electrical impulses O Auditory Nerve - sends the electrical impulses to the brain to be processed as sound Common abbreviations: O AC O AD O AS O AU O BC O HD O ENT O OM Air conduction Right ear Left ear Both ears Bone conduction Hearing distance Ear, nose and throat Otitis media Medical Vocabulary: O acoust/ hearing O -ic pertaining to O Pertaining to the sense of hearing O Acoustic O audi/o to hear O -gram a mark, a record O A record of hearing O audiogram Contd: O equilibrium O Pertaining to the sense of balance O deafness O Complete or partial loss of the ability to hear O tinnitus O The sensation of ringing in one or both ears O vertigo O Sensation of loss of equilibrium Medical instrument used to examine the eardrum O myring/o O eardrum (TM) O -scope O Instrument for examining O myringoscope Special Senses Eyes Chapter 16 Objectives: O Identify the primary functions of the eye O Introduce Medical words related to the eye O Identify selected abbreviations Ophthalm/o eye -logy study of Ophthalmology Study of the eye O Opthalmologist O opthalm/o eye O -logy O O O O O O O study of -ist one who studies Physician who specializes in the study of the eye Optometrist opt/o eye metr/ measure -ist one who specializes One who specializes in examing the eye Eyes: O Most important sense organ O Located in the orbit (bony protective cavity of the skull) O The eye lets light in, focuses it, transforms it into nerve impulses, then sends them to the brain Contd: O Light passes through the cornea, pupil, lens and O O O O O the vitreous body to rods and cones ( sensory receptors) in the retina Vision is made possible by: the coordinated actions of the nerves that control the eyeball The amount of light admitted by the pupil The focusing of light on the retina by the lens And the transmission of the image to the brain Parts to the eye: O The eye consists of the inner eye (eye ball) O And the outer eye ( the facial structures and eye muscles surrounding the eye) External Structures of the eye: O Orbital cavity: bony depression that the eyeballs fits into O Ocular muscles: attach to the sclera and move the eye O Eyelids: shield the eye from light, dust and trauma by blinking O Blephar/o eyelid O Conjunctiva: lines the eyelids and protects and lubricates the eye Contd: O The eyelids protect the eyes, shade eyes during sleep, and spread lubricating fluid. O The term DACYR/O is used to denote tears. O This lubricating fluid comes from three areas: Contd: O LACRIMAL GLANDS located above the outer corner of each eye O LACRIMAL DUCTS which drain gland secretions into the lacrimal sacs. O Lacrim/o tears O -al pertaining Internal Structures of the Eye O Eyeball: O Organ of vision O Two cavities: O ocular cavity = space in front of lens has O O O O O aqueous humor aque/o watery substance -ous pertaining to Posterior cavity = larger cavity has vitreous humor vitre/o transparent substance -ous pertaining to Inner Eye: O Made up of three layers: Outer, Middle and Inner O The outer layer contains: O Cornea: (latin word) is the transparent anterior portion of the eye O Sclera: (scler/o hard) is the white of the eye. Providing a protective covering for the eyeball Contd: O Middle layer: (uvea)- latin word means grape O Choroids: inner lining of the sclera. Contain blood vessels that nourish the eye O Ciliary muscles: muscles that adjust the shape of the lens for focusing. This produces a watery substance aqueous humor. O cili/o hairlike structure O -ary pertaining to Middle Layer Contd: O The iris is a thin diaphragm composed mostly of connective tissue and smooth muscle fibers. O The opening in the iris is the pupil O The color, texture, and patterns of each person’s iris are as unique as a fingerprint. Contd: O Inner Layer: O Retina: has layers of nervous tissue called cones and rods O Vitreous humor: jelly like matter in the back of the eye. (80% of eye volume) O This preserves the shape of the eyeball Contd: O Lens: O A clear flexible disk behind the pupil O Contains protein molecules in a crystalline structure O Function is to sharpen the focus of light on the retina O accommod/o to adapt O -ation a process O accommodation Process of vision: O Light waves from an object (such as a tree) enter the eye first through the cornea,( the clear dome at the front of the eye) O The light then progresses through the pupil. O Fluctuations in incoming light change the size of the eye’s pupil Contd: O The light continues through the vitreous humor, O then, ideally, back to a clear focus on the retina, (the retina is equivalent to the film inside of a camera, registering the tiny photos of light interacting with it). Contd: O Within the layers of the retina, light impulses are changed into electrical signals. O Then they are sent through the optic nerve, along the visual pathway, to the occipital cortex at the posterior (back) of the brain. O Here, the electrical signals are interpreted or “seen” by the brain as a visual image. Common abbreviations: O OD Right eye O OS Left eye O OU Each eye O PERRLA Pupils equal, round, and reactive to light and accommodation O VA Visual acuity O VF Visual field Contd: O Dirty contact lenses can cause a severe infection called KERATITIS. O Rupture of the cornea is known as KERATORRHEXIS. O The cornea is incised with an instrument known as a KERATOMTOME.