1. Human Anatomy & Physiology Ninth Edition PowerPoint ® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College C H A P T E R 15 © 2013 Pearson Education, Inc.© Annie Leibovitz/Contact Press Images The Special Senses: Part A

2. © 2013 Pearson Education, Inc. Special Senses Special sensory receptors –Distinct, localized receptor cells in head Vision Taste Smell Hearing Equilibrium

3. The Eye and Vision 70% of body's sensory receptors in eye Visual processing by ~ half cerebral cortex Most of eye protected by cushion of fat and bony orbit © 2013 Pearson Education, Inc. Accessory Structures of the Eye Protect the eye and aid eye function –Eyebrows –Eyelids (palpebrae) –Conjunctiva –Lacrimal apparatus –Extrinsic eye muscles

4. © 2013 Pearson Education, Inc. Eyebrow Eyelid Eyelashes Site where conjunctiva merges with cornea Palpebral Fissure (eyelid slit) Lateral commissure Iris Eyelid Surface anatomy of the right eye Pupil Sclera (covered by conjunctiva) *Lacrimal caruncle Medial commissure Figure 15.1a The eye and accessory structures. *Contains oil and sweat glands

5. © 2013 Pearson Education, Inc. Figure 15.1b The eye and accessory structures. Levator palpebrae superioris muscle (raises eyelid to open the eye) Orbicularis oculi muscle (contraction: eye closes) Eyebrow Tarsal plate (connective tissue; supports the eyelids) Cornea Palpebral fissure Eyelashes Orbicularis oculi muscle some structures shown in sagittal section Lateral view;

6. © 2013 Pearson Education, Inc. Transparent mucous membrane –Produces a lubricating mucous secretion Palpebral conjunctiva lines eyelids Bulbar conjunctiva covers white of eyes Conjunctival sac between palpebral and bulbar conjunctiva –Where contact lens rests Conjunctiva

7. Lacrimal sac Lacrimal gland Excretory ducts of lacrimal glands Lacrimal punctum Lacrimal canaliculus Nasolacrimal duct Inferior meatus of nasal cavity Nostril Lacrimal gland and ducts that drain into nasal cavity Lacrimal gland in orbit above lateral end of eye Lacrimal secretion (tears) –Dilute saline solution containing mucus, antibodies, and lysozyme –Blinking spreads tears toward medial commissure –Tears enter paired lacrimal canaliculi via lacrimal puncta –Then drain into lacrimal sac and nasolacrimal duct Lacrimal Apparatus

8. Superior oblique muscle Superior oblique tendon Superior rectus muscle Lateral rectus muscle Inferior rectus muscle Inferior oblique muscle Lateral view of the right eye Extrinsic Eye Muscles Six muscles: Four rectus muscles; names indicate movements –Superior, inferior, lateral, medial rectus muscles Two oblique muscles move eye in vertical plane and rotate eyeball –Superior and inferior oblique muscles

9. © 2013 Pearson Education, Inc. Figure 15.3b Extrinsic eye muscles. Trochlea Axis of rotation of eye Inferior rectus muscle Medial rectus muscle Lateral rectus muscle Common tendinous ring Superior oblique muscle Superior oblique tendon Superior rectus muscle Superior view of the right eye

10. © 2013 Pearson Education, Inc. Figure 15.3c Extrinsic eye muscles. Muscle ActionControlling cranial nerve Summary of muscle actions and innervating cranial nerves Lateral rectus Medial rectus Superior rectus Inferior rectus Inferior oblique Superior oblique Moves eye laterally Moves eye medially Elevates eye and turns it medially Depresses eye and turns it medially Elevates eye and turns it laterally Depresses eye and turns it laterally VI (abducens) III (oculomotor) IV (trochlear)

11. © 2013 Pearson Education, Inc. Structure of the Eyeball Wall of eyeball contains three layers –Fibrous –Vascular –Inner Internal cavity filled with fluids called humors Lens separates internal cavity into anterior & posterior segments (cavities)

12. © 2013 Pearson Education, Inc. Figure 15.4a Internal structure of the eye (sagittal section). Ciliary body Ciliary zonule (suspensory ligament) Cornea Pupil Anterior pole Anterior segment (contains aqueous humor) Lens Scleral venous sinus Posterior segment (contains vitreous humor) Diagrammatic view. The vitreous humor is illustrated only in the bottom part of the eyeball. Sclera Choroid Retina Macula lutea Fovea centralis Optic nerve Central artery and vein of the retina Optic disc (blind spot) Iris

13. © 2013 Pearson Education, Inc. Figure 15.4b Internal structure of the eye (sagittal section). Ciliary body Iris Margin of pupil Anterior segment Cornea Photograph of the human eye. Vitreous humor in posterior segment Choroid Fovea centralis Optic disc Optic nerve Lens Sclera Retina http://www.youtube.com/watch?v= TXFt1Ikl__I&feature=endscreen

14. Fibrous Layer Outermost layer; dense avascular connective tissue Two regions: sclera and cornea 1. Sclera Opaque posterior region Protects, shapes eyeball 2. Cornea Transparent anterior Bends light as it enters eye

15. Vascular Layer (Uvea) Middle pigmented layer Three regions: choroid, ciliary body, and iris 1. Choroid region (posterior portion of uvea) Supplies blood to all layers of eyeball Brown pigment absorbs light to prevent light scattering and visual confusion 2. Ciliary body Ring of tissue surrounding lens Smooth muscle bundles (ciliary muscles) control lens shape Ciliary zonule (suspensory ligament) holds lens in position 3. Iris (Colored part of eye) Pupil—central opening that regulates amount of light entering eye –Close vision and bright light—sphincter pupillae (circular muscles) contract; pupils constrict –Distant vision and dim light—dilator pupillae (radial muscles) contract; pupils dilate – sympathetic fibers –Changes in emotional state—pupils dilate when subject matter is appealing or requires problem-solving skills

16. © 2013 Pearson Education, Inc. Figure 15.5 Pupil constriction and dilation, anterior view. Sphincter pupillae muscle contracts: Pupil size decreases. Iris (two muscles) Sphincter pupillae Dilator pupillae muscle contracts: Pupil size increases. Parasympathetic + Sympathetic +

17. © 2013 Pearson Education, Inc. Inner Layer: Retina Delicate two-layered membrane –Outer Pigmented layer Single-cell-thick lining Absorbs light and prevents its scattering Phagocytize photoreceptor cell fragments Stores vitamin A –Inner Neural layer Transparent Composed of three main types of neurons –Photoreceptors, bipolar cells, ganglion cells Signals spread from photoreceptors to bipolar cells to ganglion cells Ganglion cell axons exit eye as optic nerve

18. © 2013 Pearson Education, Inc. The Retina Optic disc (blind spot) –Site where optic nerve leaves eye –Lacks photoreceptors Quarter-billion photoreceptors of two types –Rods –Cones http://www.youtube.com/watch?v=1Y- HghqvGtg&feature=related

19. © 2013 Pearson Education, Inc. Figure 15.6a Microscopic anatomy of the retina. Neural layer of retina Pathway of light Optic disc Central artery and vein of retina Pigmented layer of retina Choroid Sclera Optic nerve Posterior aspect of the eyeball

20. © 2013 Pearson Education, Inc. Figure 15.6b Microscopic anatomy of the retina. Photoreceptors Rod Cone Ganglion cells Bipolar cells Axons of ganglion cells Amacrine cell Horizontal cell Pathway of signal output Pathway of light Cells of the neural layer of the retina Pigmented layer of retina

21. © 2013 Pearson Education, Inc. Figure 15.6c Microscopic anatomy of the retina. Photomicrograph of retina Nuclei of ganglion cells Outer segments of rods and cones Choroid Axons of ganglion cells Nuclei of bipolar cells Nuclei of rods and cones Pigmented layer of retina

22. Photoreceptors Rods –Dim light, peripheral vision receptors –No color vision or sharp images –Numbers greatest at periphery Cones –Vision receptors for bright light –High-resolution color vision Fovea centralis –Tiny pit in center of macula with all cones; best vision

23. © 2013 Pearson Education, Inc. Internal Chambers and Fluids The lens and ciliary zonule separate eye into two segments – Anterior and posterior segments

24. © 2013 Pearson Education, Inc. Internal Chambers and Fluids Posterior segment contains vitreous humor that –Transmits light –Supports posterior surface of lens –Holds neural layer of retina firmly against pigmented layer –Contributes to intraocular pressure –Forms in embryo; lasts lifetime Anterior segment composed of two chambers –Anterior chamber—between cornea and iris –Posterior chamber—between iris and lens

25. Internal Chambers and Fluids Anterior segment contains aqueous humor –Plasma like fluid continuously formed by capillaries of ciliary processes –Supplies nutrients and oxygen mainly to lens and cornea but also to retina, and removes wastes Glaucoma: blocked drainage of aqueous humor increases pressure and causes compression of retina and optic nerve  blindness

26. © 2013 Pearson Education, Inc. Figure 15.4a Internal structure of the eye (sagittal section). Ciliary body Ciliary zonule (suspensory ligament) Cornea Pupil Anterior pole Anterior segment (contains aqueous humor) Lens Scleral venous sinus Posterior segment (contains vitreous humor) Diagrammatic view. The vitreous humor is illustrated only in the bottom part of the eyeball. Sclera Choroid Retina Macula lutea Fovea centralis Posterior pole Optic nerve Central artery and vein of the retina Optic disc (blind spot) Iris

27. © 2013 Pearson Education, Inc. Figure 15.8 Circulation of aqueous humor. Iris Lens epithelium Lens Cornea Corneal epithelium Corneal endothelium Aqueous humor Anterior chamber Posterior chamber Anterior segment (contains aqueous humor) Scleral venous sinus Corneoscleral junction Bulbar conjunctiva Sclera Ciliary body Ciliary zonule (suspensory ligament) Posterior segment (contains vitreous humor) Ciliary processes Ciliary muscle Aqueous humor forms by filtration from the capillaries in the ciliary processes. Aqueous humor flows from the posterior chamber through the pupil into the anterior chamber. Some also flows through the vitreous humor (not shown). Aqueous humor is reabsorbed into the venous blood by the scleral venous sinus. LensCornea 1 2 3 1 2 3

28. © 2013 Pearson Education, Inc. Lens Biconvex, transparent, flexible, and avascular Changes shape to precisely focus light on retina Two regions –Lens becomes more dense, convex, less elastic with age cataracts (clouding of lens) consequence of aging, diabetes mellitus, heavy smoking, frequent exposure to intense sunlight

29. © 2013 Pearson Education, Inc. Figure 15.9 Photograph of a cataract.

30. Visual Pathways

31. Ganglion cells of the retina make up optic nerves Left and right optic nerves (II) into brain via optic foraminae Optic chiasma (nasal side fibers cross to contralateral brain) Optic tracts (carry fibers back to the thalamsus) Ganlion cell axons terminate in lateral geniculate n. of thalamus Optic radiations carry fibers back to occipital cortex

32. The Chemical Senses: Smell And Taste Smell (olfaction) and taste (gustation) Chemoreceptors respond to chemicals in aqueous solution Taste – to substances dissolved in saliva Smell – to substances dissolved in fluids of the nasal membranes

33. Sense of Smell

34. Taste Buds Most of the 10,000 or so taste buds are found on the tongue Taste buds are found in papillae of the tongue mucosa Papillae come in three types: filiform, fungiform, and circumvallate Fungiform and circumvallate papillae contain taste buds

35. Taste Buds

36. © 2013 Pearson Education, Inc. Basic Taste Sensations There are five basic taste sensations 1.Sweet—sugars, saccharin, alcohol, some amino acids, some lead salts 2.Sour—hydrogen ions in solution 3.Salty—metal ions (inorganic salts) 4.Bitter—alkaloids such as quinine and nicotine; aspirin 5.Umami—amino acids glutamate and aspartate

37. Gustatory Pathway

38. © 2013 Pearson Education, Inc. The Ear: Hearing and Balance Three major areas of ear 1.External (outer) ear – hearing only 2.Middle ear (tympanic cavity) – hearing only 3.Internal (inner) ear – hearing and equilibrium Receptors for hearing and balance respond to separate stimuli Are activated independently

39. © 2013 Pearson Education, Inc. External Ear Auricle (pinna)Composed of –Helix (rim); Lobule (earlobe) –Funnels sound waves into auditory canal External acoustic meatus (auditory canal) –Short, curved tube lined with skin bearing hairs, sebaceous glands, and ceruminous glands –Transmits sound waves to eardrum Tympanic membrane (eardrum) –Boundary between external and middle ears –Connective tissue membrane that vibrates in response to sound –Transfers sound energy to bones of middle ear

40. © 2013 Pearson Education, Inc. Figure 15.24a Structure of the ear. External ear Middle ear Internal ear (labyrinth) Auricle (pinna) Helix Lobule External acoustic meatus Tympanic membrane Pharyngotympanic (auditory) tube The three regions of the ear

41. Middle Ear (Tympanic Cavity) A small, air-filled, mucosa-lined cavity in temporal bone –Connected laterally by eardrum –Connected medially by bony wall containing oval (vestibular) and round (cochlear) windows Epitympanic recess—superior portion of middle ear Mastoid antrum –Canal for communication with mastoid air cells Pharyngotympanic (auditory) tube—connects middle ear to nasopharynx –Equalizes pressure in middle ear cavity with external air pressure

42. © 2013 Pearson Education, Inc. Figure 15.24b Structure of the ear. Oval window (deep to stapes) Semicircular canals Vestibule Vestibular nerve Cochlear nerve Cochlea Pharyngotympanic (auditory) tube Entrance to mastoid antrum in the epitympanic recess Auditory ossicles Tympanic membrane Round window Stapes (stirrup) Incus (anvil) Malleus (hammer) Middle and internal ear

43. © 2013 Pearson Education, Inc. Otitis Media Middle ear inflammation –Especially in children Shorter, more horizontal pharyngotympanic tubes Most frequent cause of hearing loss in children –Most treated with antibiotics –Myringotomy to relieve pressure if severe Myringotomy (myringa: eardrum):A surgical procedure; a tiny incision is created in the eardrum to relieve pressure caused by excessive build-up of fluid or to drain pus from the middle ear.

44. © 2013 Pearson Education, Inc. Ear Ossicles Three small bones in tympanic cavity: the malleus, incus, and stapes –Suspended by ligaments and joined by synovial joints –Transmit vibratory motion of eardrum to oval window –Tensor tympani and stapedius muscles contract reflexively in response to loud sounds to prevent damage to hearing receptors

45. © 2013 Pearson Education, Inc. Figure 15.25 The three auditory ossicles and associated skeletal muscles. View Superior Anterior Lateral IncusMalleusEpitympanic recess Pharyngotym- panic tube Tensor tympani muscle Tympanic membrane (medial view) Stapes Stapedius muscle

46. © 2013 Pearson Education, Inc. Internal Ear Bony labyrinth –Tortuous channels in temporal bone –Three regions: 1) vestibule, 2) semicircular canals, and 3) cochlea –Filled with perilymph – similar to CSF Membranous labyrinth –Series of membranous sacs and ducts –Filled with potassium-rich endolymph

47. © 2013 Pearson Education, Inc. Figure 15.26 Membranous labyrinth of the internal ear. Temporal bone Facial nerve Vestibular nerve Superior vestibular ganglion Inferior vestibular ganglion Cochlear nerve Maculae Spiral organ Cochlear duct in cochlea Round window Stapes in oval window Saccule in vestibule Utricle in vestibule Cristae ampullares in the membranous ampullae Lateral Posterior Anterior Semicircular ducts in semicircular canals

48. © 2013 Pearson Education, Inc. Vestibule Central egg-shaped cavity of bony labyrinth Contains two membranous sacs 1.Saccule is continuous with cochlear duct 2.Utricle is continuous with semicircular canals These sacs –House equilibrium receptor regions (maculae) –Respond to gravity and changes in position of head

49. © 2013 Pearson Education, Inc. Semicircular Canals Three canals (anterior, lateral, and posterior) Membranous semicircular ducts line each canal and communicate with utricle Ampulla of each canal houses equilibrium receptor region called the crista ampullaris –Receptors respond to angular (rotational) movements of the head

50. © 2013 Pearson Education, Inc. Figure 15.26 Membranous labyrinth of the internal ear. Temporal bone Facial nerve Vestibular nerve Superior vestibular ganglion Inferior vestibular ganglion Cochlear nerve Maculae Spiral organ Cochlear duct in cochlea Round window Stapes in oval window Saccule in vestibule Utricle in vestibule Cristae ampullares in the membranous ampullae Lateral Posterior Anterior Semicircular ducts in semicircular canals

51. © 2013 Pearson Education, Inc. The Cochlea A spiral, conical, bony chamber –Size of split pea –Extends from vestibule –Contains cochlear duct, which houses spiral organ (organ of Corti) and ends at cochlear apex

52. © 2013 Pearson Education, Inc. The Cochlea Cavity of cochlea divided into three chambers –Scala vestibuli—joins oval window, contains perilymph –Scala media (cochlear duct)—contains endolymph –Scala tympani—terminates at round window; contains perilymph Scalae tympani and vestibuli are continuous with each other at helicotrema (apex)

53. © 2013 Pearson Education, Inc. Figure 15.27b Anatomy of the cochlea. Vestibular membrane Tectorial membrane Cochlear duct (scala media ; contains endolymph) Stria vascularis Spiral organ Basilar membrane Scala vestibuli (contains perilymph) Scala tympani (contains perilymph) Osseous spiral lamina Spiral ganglion

54. Figure 15.27a Anatomy of the cochlea. Helicotrema at apex Modiolus: Coils around bony pillar Cochlear nerve, division of the vestibulocochlear nerve (VIII) Spiral ganglion Osseous spiral lamina Vestibular membrane Cochlear duct (scala media) The "roof" of cochlear duct: Vestibular membrane External wall is stria vascularis – secretes endolymph "Floor" of cochlear duct composed of –Bony spiral lamina –Basilar membrane, which supports spiral organ The cochlear branch of nerve VIII runs from spiral organ to brain

55. © 2013 Pearson Education, Inc. Tectorial membrane Hairs (stereocilia) Outer hair cells Supporting cells Inner hair cell Afferent nerve fibers Fibers of cochlear nerve Basilar membrane Figure 15.27c Anatomy of the cochlea.

56. © 2013 Pearson Education, Inc. Figure 15.27d Anatomy of the cochlea. Inner hair cell Outer hair cell

57. Simplified Auditory Pathways