Chapter 11 Medical Terminology and Chapter 10 Body Structures: SPECIAL SENSES Medical terminology chapter 11, pages 308 – 326. Exercises: 1 – 100. Body structures chapters 10, pages 172 – 189. Exercises: Review questions, labeling. Body structures workbook chapter 10. Exercises: A, B, D, F, H, K. Delmar video “The Special Senses”, tape 14.

Functions of the Eyes – receive images and transmit to brain receptor organs of sight Optic: pertaining to eye or sight Ocular: pertaining to the eye Extraocular: outside the eyeball Intraocular: within the eyeball

Structures of the Eye ADNEXA – accessory structures Orbit Eye Muscles Eyelids Eyelashes Conjunctiva Lacrimal Apparatus www.ipo.tue.nl/.../seminar-2%20human/ sld015.htm

What structure contains and protects the eyeball and its associated muscles, blood vessels, and nerves ORBIT Frontal Sphenoid Ethmoid Maxilla Zygoma Lacrimal Palatine www.lau-verlag.de/anatom/ skeletal-system.htm

Muscles of the Eye 6 Major muscles attached to each eye Superior/Inferior Rectus Superior/Inferior Oblique Lateral/Medial Rectus Binocular means both eyes working together.

Eyelids: protect the eyeball from foreign matter, excessive light, and impact Canthus: angle where upper/lower eyelids meet Inner Canthus Outer Canthus Conjunctiva: lines the underside of each eyelid and provides protective covering over exposed surface of eyeball

The Lacrimal Apparatus – structures that produce, store, and remove tears Lacrimal Glands: secrete lacrimal fluid to maintain moisture on the anterior surface of the eyeball Lacrimal Canaliculi: ducts at the inner canthus of each eye – collect tears and drain them into the lacrimal sac Lacrimal sac: an enlargement of the upper portion of the lacrimal duct Lacrimal duct: passageway that drains lacrimal fluid into the nose

Eyebrows and Eyelashes Prevent foreign matter from reaching the eye Cilia – small hairs that are located along the edges of the eyelids (eyelashes)

The Eyeball - globe Made up of 3 layers Sclera Choroid Retina Interior of eye is divided into anterior/posterior segments www.optelec.com/ lv_ref.php

The Sclera – the white of the eye Outer layer of eye Maintains shape of the eye and protects the delicate inner layers of tissue Cornea: transparent anterior portion of the sclera Provides most of the optical power of the eye

The Uveal Tract The vascular layer of eye Choroid: opaque (light cannot pass through it) middle layer of the eyeball – provides blood supply for entire eye Iris: colored layer that surrounds pupil – it’s muscles control amount of light entering eye – decrease - muscles contract making opening smaller (visa versa) Pupil: black circular opening in center of iris – permits light to enter eye Lens: focuses images on the retina – located behind iris and pupil Ciliary Body: located within the choroid, set of muscles and ligaments that adjust lens to refine the focus of light rays on the retina Near-by objects = thicker Distance objects = thinner

The Retina Nerve layer located between the posterior chamber and the choroid layer at the back of the eye Contains light sensitive rods (black/white receptors) and cones (color receptors) Receive images and convert them into nerve impulses Optic disk: (blind spot) – contains no rods/cones – nerve endings of retina gather to form optic nerve which transmits nerve impulses from the retina to the brain

The Anterior Segment – front 1/3 of eye Divided into anterior and posterior chambers Anterior chamber behind the cornea in front of the iris Posterior chamber Between the back of the iris and the front of the lens These chambers filled with aqueus humor (fluid) Nourishes intraocular structures Constantly filtered and drained which regulates intraocular pressure (IOP = btwn 12 & 21 mm Hg)

The Posterior Segment – posterior 2/3 of eye Aids in maintaining the shape of the eye Contains vitreous humor Lined with retina and it’s related structures

Normal Action of the Eye Accommodation: the eyes make adjustments for seeing at various distances Includes constriction or dilation of the pupil, movement of the eye, and changes in the shape of the lens Convergence: simultaneous inward movement of both eyes – in an effort to maintain single binocular vision as an object comes nearer Visual Acuity: the ability to distinguish object details and shape at a distance Normal vision = 20/20 Snellen Chart: used to measure visual acuity

Glaucoma Glaucoma is the increase of the IOP (intra-ocular pressure)

Macular Degeneration Loss of central vision over a period of time but, not total blindness

Pathology of the Eyes - EYELIDS Blepharoptosis (A) Ectropion (B) Entropion (C) Hordeolum: (D) A B D C

Functions of the Ears Receive sound impulses and transmit them to the brain Inner also helps maintain balance Auditory: pertaining to the sense of hearing Acoustic: relating to sound or hearing

Structures of the Ear The Outer Ear The Middle Ear The Inner Ear The Auditory Ossicles The Eustachian Tubes The Inner Ear

The Outer Ear Pinna: auricle – External portion Catches sound waves and transmits them into the external auditory canal (EAC) EAC: transmits sound waves from pinna to middle ear What is the name for the sticky yellow-brown substance that functions to prevent bacteria and dust from entering the middle ear?? CERUMEN (earwax)

The Middle Ear Tympanic Membrane (eardrum) Transmits sound by vibrating Surrounded by hollow air spaces – mastoid cells (which can easily become involved in a middle ear infection)

The Auditory Ossicles Malleus: hammer Incus: anvil Stapes: stirrup 3 small bones in the middle ear Transmit sound waves from the eardrum to the inner ear by vibration Named for their shape Malleus: hammer Incus: anvil Stapes: stirrup

malleus stapes incus

The Inner Ear- labyrinth Contains sensory receptors for hearing and balance Cochlea: spiral shaped passage that leads from the oval window Cochlear duct: filled with fluid that vibrates when sound waves strike it Organ of Corti: receptor site that receives vibrations and relays them to the auditory nerve fibers that transmit them to the auditory center of the cerebral cortex, where they are interpreted and heard Semicircular canals: helps maintain equilibrium

Normal Action of the Ears Air conduction: sound waves enter the ear through the pinna, travel down the auditory canal, and strike the TM between the outer and middle ear Bone conduction: as the eardrum vibrates, it moves the auditory ossicles and these conduct sound waves through the middle ear Sensorineural conduction: sound vibrations reach the inner ear via the oval window where the structures of the inner ear receive the sound waves and relay them to the brain

Pathology of the Ears Outer Ear Middle Ear Inner Ear Hearing Loss Otalgia: earache Otitis: inflammation of the ear Otomycosis: swimmer’s ear Middle Ear Eustachitis: inflammation of the eustachian tube Mastoiditis Otosclerosis: ankylosing of the bones of the middle ear = hearing loss Otitis Media Inner Ear Meniere’s syndrome: vertigo, fluctuating hearing loss, tinnitus (ringing or buzzing in the ears) Hearing Loss Deafness Noise-Induced hearing loss

Diagnostic Procedures of the Ears Audiometry: use of audiometer to measure hearing Speech audiometry: measures the threshold of speech reception and speech discrimination Monaural: testing involving one ear Binaural: testing involving both ears

audiometry Both ears - AU Right ear - AD Left ear - AS

Treatment Procedures of the Ears Outer Ear Otoplasty: surgical repair of the pinna of the ear Middle Ear Mastoidectomy Tympanocentesis Tympanostomy tubes Inner Ear Fenestration Labyrinthectomy Labyrinthotomy

Mastoidectomy otoplasty labyrinthectomy tympanostomy