Anatomy and Physiology 8 - The Special Senses PDF

ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B FIVE SENSES EYEBROWS  VISION (Sight)...

ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B FIVE SENSES EYEBROWS  VISION (Sight)  Coarse hairs that overlie the supraorbital margins  HEARING  FUNCTIONS INCLUDE:  SMELL  Shading the eye  TASTE  Preventing perspiration from reaching the eye  TOUCH (Palpation)  ORBICULARIS MUSCLE – depresses the eyebrows  CORRUGATOR MUSCLES – move the eyebrows medially TASTE BUDS  Most of the 10,000 or so taste buds are found on the tongue PALPEBRAE (EYELIDS)  Taste buds are found in papillae of the tongue mucosa  Protect the eye anteriorly  PAPILLAE COME IN THREE TYPES: filiform, fungiform, and circumvallate  PALPEBRAL FISSURE – separates eyelids  Fungiform and circumvallate papillae contain taste buds  CANTHI – medial and lateral angles (commissures) PALPEBRAE (EYELIDS)  LACRIMAL CARUNCLE – contains glands that secrete a whitish, oily secretion (Sandman’s eye sand)  TARSAL PLATES OF CONNECTIVE TISSUE support the eyelids internally  LEVATOR PALPEBRAE SUPERIORIS – gives the upper eyelid mobility  EYELASHES  Project from the free margin of each eyelid  Initiate reflex blinking  LUBRICATING GLANDS ASSOCIATED WITH THE EYELIDS  Meibomian glands and sebaceous glands  Ciliary glands lie between the hair follicles TASTE SENSATIONS  There are five basic taste sensations  SWEET – sugars, saccharin, alcohol, and some amino acids  SALT – metal ions  SOUR – hydrogen ions  BITTER – alkaloids such as quinine and nicotine  UMAMI – elicited by the amino acid glutamate SENSE OF SMELL  The organ of smell is the olfactory epithelium, which covers the superior nasal concha  Olfactory receptor cells are bipolar neurons with radiating olfactory cilia CONJUNCTIVA  Olfactory receptors are surrounded and cushioned by supporting cells  TRANSPARENT MEMBRANE THAT:  Basal cells lie at the base of the epithelium  Lines the eyelids as the palpebral conjunctiva  Covers the whites of the eyes as the ocular conjunctiva  Lubricates and protects the eye LACRIMAL APPARATUS  Consists of the lacrimal gland and associated ducts  Lacrimal glands secrete tears  TEARS  Contain mucus, antibodies, and lysozyme  Enter the eye via superolateral excretory ducts  Exit the eye medially via the lacrimal punctum  Drain into the nasolacrimal duct VISION  70% of all sensory receptors are in the eye  Most of the eye is protected by a cushion of fat and the bony orbit  Accessory structures include eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles  ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B EXTRINSIC EYE MUSCLES PUPIL DILATION AND CONSTRICTION  Six straplike extrinsic eye muscles  Enable the eye to follow moving objects  Maintain the shape of the eyeball  Four rectus muscles originate from the annular ring  Two oblique muscles move the eye in the vertical plane SENSORY TUNIC: RETINA  A delicate two-layered membrane  PIGMENTED LAYER – the outer layer that absorbs light and prevents its scattering  NEURAL LAYER, WHICH CONTAINS:  Photoreceptors that transduce light energy SUMMARY OF CRANIAL NERVES AND MUSCLE ACTIONS  Bipolar cells and ganglion cells  Names, actions, and cranial nerve innervation of the extrinsic eye  Amacrine and horizontal cells muscles STRUCTURE OF THE EYEBALL THE RETINA: GANGLION CELLS AND THE OPTIC DISC  GANGLION CELL AXONS:  Run along the inner surface of the retina  Leave the eye as the optic nerve  THE OPTIC DISC:  Is the site where the optic nerve leaves the eye  Lacks photoreceptors (the blind spot) FIBROUS TUNIC  Forms the outermost coat of the eye and is composed of:  OPAQUE SCLERA (posteriorly)  CLEAR CORNEA (anteriorly)  The sclera protects the eye and anchors extrinsic muscles  The cornea lets light enter the eye VASCULAR TUNIC (UVEA)  HAS THREE REGIONS: choroid, ciliary body, and iris  CHOROID REGION  A dark brown membrane that forms the posterior portion of the uvea  Supplies blood to all eye tunics  CILIARY BODY  A thickened ring of tissue surrounding the lens  Composed of smooth muscle bundles (ciliary muscles)  Anchors the suspensory ligament that holds the lens in THE RETINA: PHOTORECEPTORS place  RODS:  IRIS  Respond to dim light  The colored part of the eye  Are used for peripheral vision  Pupil – central opening of the iris  CONES:  Regulates the amount of light entering the eye during:  Respond to bright light  Close vision and bright light – pupils constrict  Have high-acuity color vision  Distant vision and dim light – pupils dilate  Are found in the macula lutea  Changes in emotional state – pupils dilate when the  Are concentrated in the fovea centralis subject matter is appealing or requires problem- solving skills  ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B BLOOD SUPPLY TO THE RETINA  The neural retina receives its blood supply from two sources  The outer third receives its blood from the choroid  The inner two-thirds is served by the central artery and vein  Small vessels radiate out from the optic disc and can be seen with an ophthalmoscope INNER CHAMBERS AND FLUIDS  The Lens separates the internal eye into anterior and posterior segments  THE POSTERIOR SEGMENT IS FILLED WITH A CLEAR GEL CALLED VITREOUS HUMOR THAT:  Transmits light  Supports the posterior surface of the lens  Holds the neural retina firmly against the pigmented layer  Contributes to intraocular pressure ANTERIOR SEGMENT  COMPOSED OF TWO CHAMBERS  ANTERIOR – between the cornea and the iris  POSTERIOR – between the iris and the lens  AQUEOUS HUMOR  A plasmalike fluid that fills the anterior segment  Drains via the canal of Schlemm  SUPPORTS, NOURISHES, AND REMOVES WASTES VISUAL ACUITY TEST PHOTORECEPTION: FUNCTIONAL ANATOMY OF PHOTORECEPTORS  PHOTORECEPTION – process by which the eye detects light energy  Rods and cones contain visual pigments (photopigments) REFRACTION AND LENSES  Arranged in a stack of disklike infoldings of the plasma  When light passes from one transparent medium to another its speed membrane that change shape as they absorb light changes and it refracts (bends)  Light passing through a convex lens (as in the eye) is bent so that the rays converge to a focal point  When a convex lens forms an image, the image is upside down and reversed right to left ERRORS OF REFRACTION  MYOPIA = NEARSIGHTEDNESS  Eyeball too long  Images form in front of retina  HYPEROPIA = FARSIGHTEDNESS  Eyeball too short  Images form behind retina  ASTIGMATISM = irregularity in curve of cornea or lens  Glasses can correct most of these impairments  ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B VISUAL FIELD DEFECTS MIDDLE EAR (TYMPANIC CAVITY)  A small, air-filled, mucosa-lined cavity  Flanked laterally by the eardrum  Flanked medially by the oval and round windows  EPITYMPANIC RECESS – superior portion of the middle ear  PHARYNGOTYMPANIC TUBE – connects the middle ear to the nasopharynx  Equalizes pressure in the middle ear cavity with the external air pressure EAR OSSICLES  The TYMPANIC CAVITY CONTAINS THREE SMALL BONES: the malleus, incus, and stapes  Transmit vibratory motion of the eardrum to the oval RODS window  FUNCTIONAL CHARACTERISTICS  Dampened by the tensor tympani and stapedius muscles  Sensitive to dim light and best suited for night vision  Absorb all wavelengths of visible light INNER EAR  Perceived input is in gray tones only  BONY LABYRINTH  Sum of visual input from many rods feeds into a single  Tortuous channels worming their way through the ganglion cell temporal bone  Results in fuzzy and indistinct images  Contains the vestibule, the cochlea, and the semicircular canals CONES  Filled with perilymph  FUNCTIONAL CHARACTERISTICS  MEMBRANOUS LABYRINTH  Need bright light for activation (have low sensitivity)  Series of membranous sacs within the bony labyrinth  Have pigments that furnish a vividly colored view  Filled with a potassium-rich fluid  Each cone synapses with a single ganglion cell  Vision is detailed and has high resolution THE EAR: HEARING AND BALANCE  The Three Parts Of The Ear are the inner, outer, and middle ear  The outer and middle ear are involved with hearing  The inner ear functions in both hearing and equilibrium  RECEPTORS FOR HEARING AND BALANCE:  Respond to separate stimuli  Are activated independently THE COCHLEA  The scala tympani terminates at the round window  THE SCALAS TYMPANI AND VESTIBULI:  Are filled with perilymph  Are continuous with each other via the helicotrema  The scala media is filled with endolymph OUTER EAR  THE “FLOOR” OF THE COCHLEAR DUCT IS COMPOSED OF:  THE AURICLE (PINNA) IS COMPOSED OF:  The bony spiral lamina  The helix (rim)  The basilar membrane, which supports the organ of Corti  The lobule (earlobe)  The cochlear branch of nerve VIII runs from the organ of Corti to the  EXTERNAL AUDITORY CANAL brain  Short, curved tube filled with ceruminous glands  TYMPANIC MEMBRANE (EARDRUM)  Thin connective tissue membrane that vibrates in response to sound  Transfers sound energy to the middle ear ossicles  Boundary between outer and middle ears  ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B PROPERTIES OF SOUND  SOUND IS:  A pressure disturbance (alternating areas of high and low pressure) originating from a vibrating object  Composed of areas of rarefaction and compression  Represented by a sine wave in wavelength, frequency, and amplitude PROPERTIES OF SOUND  FREQUENCY – the number of waves that pass a given point in a given time  PITCH – perception of different frequencies (we hear from 20–20,000 Hz) TRANSMISSION OF SOUND TO THE INNER EAR  The route of sound to the inner ear follows this pathway:  OUTER EAR – pinna, auditory canal, eardrum  MIDDLE EAR – malleus, incus, and stapes to the oval INNER EAR OR BONY LABYRINTH window  Also known as osseous labyrinth-twisted bony tubes  INNER EAR – scalas vestibuli and tympani to the cochlear  Includes sense organs for hearing and balance duct  Filled with a fluid called perilymph, which cushions and protects the  Stimulation of the organ of Corti inner structures.  Generation of impulses in the cochlear nerve AUDITORY & SPEECH PROBLEMS  EXTERNAL OTITIS OR ACUTE OTITIS EXTERNA  GENERAL CONSIDERATION & CAUSES:  Inflammation w/ Infection of the External Ear;  Causes maybe: Water w/in the Ear Canal also called:  “SWIMMER’S EAR” → Organisms enters the  EXTERNAL EAR TISSUES → causing  Vibrations of the stapes push and pull on the membranous oval Infection; window, moving the perilymph through the cochlea. The round  Most Common Pathogens: Bacterial & Fungal; window is a membrane-covered opening in the cochlea that acts as a  Common Bacteria: Staph. Aureus & pressure release valve. Pseudomonas Species;  Common Fungus: Aspergillus Specie;  Maybe triggered by Allergies from Hair Sprays & Dyes causing Allergic Dermatitis affecting the External Ear.  Sns & Sxs:  Ear Pain or Aural Tenderness from Swelling & Inflammation ;  Initial Discharges maybe Watery to Serosanguinous;  Fever, Cellulitis of the Skin, Lymphadenopathy;  Hearing Loss from Obstruction of the Ear Canal;  Otoscopic Exam: Ear Canal is Edematous & Erythematous;  Ear Discharges maybe: Foul Smelling Yellow to Green in Color for untreated cases;  Fungus Infection: Hair-like Black Spores visible grossly;  ANATOMY AND PHYSIOLOGY 8 - The Special Senses Sharmane C. Gonzales BSN - 1B  TREATMENT: CHRONIC OTITIS MEDIA  Principles of Treatment Aimed at:  is the result of a prolong middle ear infection with perforation of the ☞ Relieving Discomfort; eardrum. ☞ Reduce Swelling causing the Pain;  affects 20-40% of all children under the age 6 ☞ Eradicating Infection.  Analgesic / Anti-pyretic for Pain & Fever; ACUTE OTITIS MEDIA  Anti-biotic Ear Drops.  also known as “ bacterial otitis media  acute infection of the middle ear usually started by an infection in the OTITIS MEDIA URT  ALTERNATE NAMES:  is the most frequent diagnosis of children in clinical practice  Chronic Ear Infection, Chronic Otitis Media, Ear Infection - Chronic, Middle Ear Infection - Chronic CHRONIC OTITIS MEDIA  DEFINITION  is the result of a prolong middle ear infection with perforation of the  inflammation of the middle ear, or tympanum. eardrum.  Otitis media is an inflammation and/or infection of the  affects 20-40% of all children under the age 6 middle ear.  Acute otitis media (acute ear infection) occurs when there is bacterial or viral infection of the fluid of the middle ear, which causes production of fluid or pus.  Chronic otitis media occurs when the eustachian tube becomes blocked repeatedly due to allergies, multiple infections, ear trauma, or swelling of the adenoids.