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Home , Choroid, Ciliary body, Ciliary processes, Inner limiting membrane, Outer nuclear layer, Outer plexiform layer

Lab 20 – Special Senses IUSM – 2016

I. Introduction Special Senses II. Keywords III. Slides A. 1. General structure 2. 3. Layers a. Fibrous tunic i. ii. b. Vascular tunic i. ii. iii. c. Neural tunic () 4. B. C. Ear 1. General structure 2. Parts a. External ear b. Inner ear IV. Summary Fig 23-1, Junqueira, 13th ed. Lab 20 – Special Senses IUSM – 2016

I. Introduction Keywords II. Keywords III. Slides Anterior chamber Nucleated fibers A. Eye Bowman’s membrane 1. General structure Canal of Schlemm Optic nerve 2. Lens Choroid 3. Layers Ciliary body Pigmented epithelium a. Fibrous tunic Posterior chamber i. Cornea Cochlea Retina ii. Sclera Cochlear duct Rods b. Vascular tunic Cones Scala media i. Iris Scala tympani Cornea Scala vestibuli ii. Ciliary body Descement’s membrane Scleral venous sinus iii. Choroid Dilator pupillae m. Sphincter pupillae m. c. Neural tunic (Retina) Fovea Spiral 4. Optic Nerve Hair cells Spiral organ of Corti B. Eyelid Stria vascularis C. Ear Substantia propria 1. General structure Iris Suspensory ligament 2. Parts Lens Tarsal plate a. External ear Limbus Tectorial membrane b. Inner ear Meibomian glands Vestibular membrane IV. Summary Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction Slide Overview II. Keywords III. Slides A. Eye 1. General structure 2. Lens anterior 3. Layers cavity a. Fibrous tunic i. Cornea lens optic nerve ii. Sclera posterior cavity (CN II) b. Vascular tunic cornea () i. Iris ii. Ciliary body iii. Choroid c. Neural tunic (Retina) iris 4. Optic Nerve w/ B. Eyelid C. Ear 1. General structure 2. Parts a. External ear b. Inner ear neural tunic sclera IV. Summary vascular tunic fibrous tunic Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers a. Fibrous tunic i. Cornea ii. Sclera b. Vascular tunic lens i. Iris ii. Ciliary body posterior anterior iii. Choroid cavity c. Neural tunic (Retina) chamber (vitreous chamber) between cornea and iris 4. Optic Nerve anterior B. Eyelid posterior cavity chamber C. Ear between iris and lens 1. General structure 2. Parts a. External ear the eye is divided into two cavities based upon the lens: posterior to the lens is the posterior cavity containing b. Inner ear the (humor) which is a large gelatinous mass of transparent composed mainly IV. Summary of water; anterior to the lens is the anterior cavity which is subdivided into the anterior and posterior chambers based upon the iris; the anterior cavity is filled with aqueous humor which is produced by the ciliary processes in the posterior chamber and flows through the pupil into the anterior chamber Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure non-nucleated 2. Lens fibers (contain crystallin proteins) 3. Layers a. Fibrous tunic i. Cornea ii. Sclera differentiation b. Vascular tunic i. Iris ii. Ciliary body nucleated fibers iii. Choroid c. Neural tunic (Retina) subcapsular epithelium 4. Optic Nerve capsule B. Eyelid (basal lamina) C. Ear 1. General structure 2. Parts a. External ear the lens is an avascular, biconvex, transparent disc derived from epithelium and attached to the ciliary body by b. Inner ear the suspensory ligament; the flexibility of the lens allows it to change shape to affect light refraction upon the IV. Summary retina; its transparency is principally due to the loss of light-scattering organelles (such as the nucleus), the presence of crystallin proteins, and the precise shape and organized packing of its non-nucleated fibers Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E

I. Introduction II. Keywords the fibrous tunic is the outermost layer III. Slides of the eye; it consists of two major regions: A. Eye th cornea 1. General structure 1. sclera - posterior 5/6 ; the “white” 2. Lens of the eye; consists of dense CT that 3. Layers protects the eye and serves as site for extraocular muscle attachment a. Fibrous tunic th i. Cornea 2. cornea - anterior 1/6 ; transparent ii. Sclera and avascular; serves as primary b. Vascular tunic site of light refraction; of pain receptors is >100x greater than i. Iris in skin and >10x than in dental pulp ii. Ciliary body iii. Choroid c. Neural tunic (Retina) 4. Optic Nerve sclera B. Eyelid C. Ear 1. General structure the sclera and cornea are joined at the limbus (Lt. “edge”) 2. Parts which encircles the cornea and serves as its source of limbus a. External ear cornea stem cells; it becomes more stratified at the conjunctiva b. Inner ear which is the stratified columnar mucous membrane with IV. Summary numerous goblet cells that covers the exposed portion of the sclera (not the cornea) and the inside of the eyelid conjunctiva Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers a. Fibrous tunic i. Cornea ii. Sclera corneal corneal b. Vascular tunic epithelium endothelium lamellae of bundles with i. Iris stratified interspersed keratocytes simple ii. Ciliary body squamous squamous iii. Choroid c. Neural tunic (Retina) 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear Bowman’s membrane Descemet’s membrane (des-suh-mays) b. Inner ear (anterior limiting membrane) (posterior limiting membrane) IV. Summary Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers a. Fibrous tunic i. Cornea ii. Sclera corneal b. Vascular tunic epithelium i. Iris ii. Ciliary body iii. Choroid c. Neural tunic (Retina) Bowman’s 4. Optic Nerve membrane B. Eyelid C. Ear 1. General structure 2. Parts a. External ear b. Inner ear the is nonkeratinized stratified squamous epithelium generally with 5-7 cell layers; cell IV. Summary turnover is about 7 days from stem cells located in the limbus; unlike the overlying epithelium, Bowman’s membrane is relatively static and does not regenerate after injury; the uniform orientation of the CT fibers within the substantia propria contributes to corneal transparency Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens Descemet’s membrane 3. Layers (des-suh-mays) a. Fibrous tunic i. Cornea ii. Sclera keratocyte b. Vascular tunic i. Iris ii. Ciliary body iii. Choroid c. Neural tunic (Retina) 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear the cornea is avascular, so most metabolic exchange occurs across the corneal endothelium with the aqueous b. Inner ear humor in the anterior chamber; additionally the endothelium keeps the cornea dehydrated by actively pumping Na+ into the chamber (water follows); Descemet’s membrane separates the endothelium from the substantia IV. Summary propria, but unlike Bowman’s membrane it is readily regenerated after injury if the endothelium is intact; unlike the corneal epithelium, the endothelium has limited regenerative potential Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides retina A. Eye 1. General structure 2. Lens 3. Layers choroid a. Fibrous tunic i. Cornea ii. Sclera b. Vascular tunic i. Iris ii. Ciliary body sclera iii. Choroid c. Neural tunic (Retina) 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear th b. Inner ear the sclera (Gr. “hard”) is the opaque layer of dense CT constituting the posterior 5/6 of the fibrous tunic; it IV. Summary serves to maintain the rigidity of the eye and as the site of attachment for the tendons of the Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords the vascular tunic () is the middle layer of the III. Slides eye; it consists of three parts: A. Eye 1. General structure 1. iris: most anterior portion of vascular tunic; contains many melanocytes that provide the ciliary choroid 2. Lens color of the eye and prevent the passage of body 3. Layers light, leaving only the central pupil (opening) a. Fibrous tunic for light to pass through; contains: iris i. Cornea a. dilator pupillae m. ii. Sclera b. Vascular tunic b. sphincter pupillae m. i. Iris p 2. ciliary body: expansion of the vascular tunic, ii. Ciliary body u encircling the lens; consists of: p iii. Choroid a. i c. Neural tunic (Retina) l 4. Optic Nerve b. ciliary processes B. Eyelid 3. choroid: located in posterior 2/3rd of eye; C. Ear contains: 1. General structure a. loose CT 2. Parts b. lots of vasculature a. External ear b. Inner ear c. melanocytes IV. Summary Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers stroma a. Fibrous tunic i. Cornea dilator pupillae m. ii. Sclera b. Vascular tunic i. Iris anterior ii. Ciliary body chamber iii. Choroid sphincter pupillae m. c. Neural tunic (Retina) 4. Optic Nerve pigmented epithelium B. Eyelid C. Ear 1. General structure 2. Parts a. External ear the iris consists of a CT stroma with an uncovered anterior surface, not lined by an epithelium bordering the anterior chamber; the posterior blocks light entering the eye except through the pupil b. Inner ear pigmented epithelium and separates the stroma from the posterior chamber, however the basal lamina faces the chamber side, not the IV. Summary stroma; the sphincter pupillae m. has parasympathetic innervation and constricts the pupil; the dilator pupillae m. is a thin layer of myoepithelial cells with sympathetic innervation that dilate the pupil Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye ciliary 1. General structure body 2. Lens 3. Layers a. Fibrous tunic ciliary processes i. Cornea ii. Sclera b. Vascular tunic scleral i. Iris venous sinus ii. Ciliary body (canal of Schlemm) iii. Choroid and c. Neural tunic (Retina) 4. Optic Nerve lens iris B. Eyelid C. Ear 1. General structure 2. Parts the ciliary body controls the shape of the lens and produces aqueous humor; it is composed of the ciliary muscle and the ciliary processes; the is attached to the lens via zonular fibers from between the a. External ear ciliary muscle ciliary processes to form the suspensory ligament; during , contraction of the ciliary muscle b. Inner ear releases tension on the ligament causing the lens to thicken permitting focus on near objects; the ciliary IV. Summary processes are covered by a double layer of columnar epithelium which secretes aqueous humor into the posterior chamber; the aqueous humor then passes through the pupil to enter the anterior chamber where it drains into the trabecular meshwork and the scleral venous sinus to return to the systemic circulation Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens the choroid contains loose 3. Layers CT, vasculature, and a. Fibrous tunic melanocytes i. Cornea the vasculature provides

ii. Sclera cavity oxygen and nutrients to the b. Vascular tunic adjacent tissues i. Iris the melanocytes provide the

ii. Ciliary body posterior dark coloration of the choroid iii. Choroid chamber) (vitreous and serve to absorb scattered c. Neural tunic (Retina) light and reduce reflection 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear retina sclera b. Inner ear choroid (neural tunic) (vascular tunic) (fibrous tunic) IV. Summary Lab 20 – Special Senses IUSM – 2016 Slide 78: Eye, H&E I. Introduction II. Keywords posterior cavity 1. inner limiting layer: basal lamina of Müller cells (glial cells) which III. Slides support the cells and processes of retina; they extend to the outer limiting A. Eye layer, where they form tight/adherens junctions with rods and cones 1. General structure 2. nerve fiber layer: axons from ganglionic layer below; axons converge 2. Lens at the optic disc and collectively leave the eye as the optic nerve 3. Layers a. Fibrous tunic 3. ganglionic layer: cell bodies of multipolar ganglion cells; axons will i. Cornea collectively form the optic nerve ii. Sclera 4. inner plexiform layer: axodendritic connections between bipolar b. Vascular tunic and ganglion cells i. Iris ii. Ciliary body 5. : cells bodies of bipolar cells and other neurons; iii. Choroid bipolar cells (interneurons) connect photoreceptors to ganglion cells c. Neural tunic (Retina) 6. outer plexiform layer: axodendritic connections between 4. Optic Nerve photoreceptors and neurons from the inner nuclear layer B. Eyelid 7. : cell bodies of rods and cones (photoreceptors) C. Ear 1. General structure 8. outer limiting layer: junctions between rods/cones and Müller cells 2. Parts 9. photoreceptors: photosensitive processes of rods (light) and cones (color) a. External ear 10. pigmented epithelium: -containing cuboidal epithelium; absorbs b. Inner ear light, forms part of blood-retina barrier, and aids chromophore recycling IV. Summary choroid of vascular tunic Lab 20 – Special Senses pathway of “information”: IUSM – 2016 inhibition of photoreceptors (inhibitory): photons hit chromophore molecules (e.g., retinal in rods) on “stacked” I. Introduction membranes of photoreceptors (rods or cones); the energized II. Keywords chromophore leads to a confirmation change in its associated III. Slides protein (rhodopsin in rods, or one of 3 iodopsins for cones); the opsin activates transducin, leading to decreased A. Eye cGMP and closure of Na+ channels; cell becomes hyperpolarized 1. General structure and stops releasing neurotransmitter (glutamate) to bipolar cells 2. Lens 4 bipolar cells are no longer inhibited by photoreceptors; they 3. Layers 1 2 3 4 depolarize and send action potentials (APs) to ganglion cells a. Fibrous tunic ganglion cells conduct APs through axons into optic nerve i. Cornea optic nerve  optic chiasm  LGN (thalamus)  primary ii. Sclera visual cortex in occipital lobe of brain  “vision” b. Vascular tunic i. Iris ii. Ciliary body iii. Choroid pathway of light: c. Neural tunic (Retina) through cornea where it is refracted (air-corneal surface), 4. Optic Nerve accounting for 2/3 of eye’s total optical power B. Eyelid through anterior cavity, where additional refraction occurs; C. Ear muscles of the iris regulate amount of light passing through 3 1. General structure pupil and “entering the eye” 2 2. Parts through the lens it again is refracted; the lens accounts for 1 a. External ear 1/3 of the eye’s total optical power; ciliary mm. can affect b. Inner ear shape of lens (contract to loosen tension on suspensory 5 ligaments to accommodate near vision) affecting refraction IV. Summary through vitreous body, transmitting light to retina

through retinal layers to “deepest” level for photoreceptors Lab 20 – Special Senses IUSM – 2016 Slide 49a (464): Optic Nerve, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens optic nerve 3. Layers a. Fibrous tunic i. Cornea ii. Sclera optic disc (blind spot) b. Vascular tunic i. Iris ii. Ciliary body retina iii. Choroid detachment of the retina from c. Neural tunic (Retina) the pigemented epithelium is an 4. Optic Nerve artifact of slide preparation B. Eyelid C. Ear 1. General structure 2. Parts a. External ear nerve fibers from the retina (cell bodies in the ganglionic layer) converge at the optic disc to form the optic b. Inner ear nerve (CN II), which carries the sensory information into the brain; because the optic disc consists of bundles of IV. Summary nerve fibers and lacks photoreceptors, it is a “blind spot” in the Lab 20 – Special Senses IUSM – 2016 Slide 138: Eyelid, H&E I. Introduction II. Keywords III. Slides external A. Eye look here for skin and 1. General structure follicles of 2. Lens 3. Layers a. Fibrous tunic skeletal muscle of i. Cornea orbicularis oculi m., ii. Sclera and levator palpebrae m. b. Vascular tunic in upper eyelid i. Iris ii. Ciliary body iii. Choroid look here for conjunctiva c. Neural tunic (Retina) 4. Optic Nerve B. Eyelid C. Ear internal 1. General structure 2. Parts a. External ear b. Inner ear the provide a protective covering of the anterior surface of the eye; they consist of skin lining the outer IV. Summary surface and an inner core of fibroelastic CT known as the tarsus (Gr. “flat surface”); lining the innermost surface of the tarsus is the conjunctiva (mucous membrane) continuous onto the anterior sclera of the eye Lab 20 – Special Senses IUSM – 2016 Slide 138: Eyelid, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers a. Fibrous tunic i. Cornea tarsus ii. Sclera (tarsal plate) b. Vascular tunic dense fibroelastic CT that i. Iris contributes form and ii. Ciliary body support to the eyelid iii. Choroid c. Neural tunic (Retina) 4. Optic Nerve B. Eyelid C. Ear 1. General structure tarsal (Meibomian) glands conjunctiva 2. Parts a. External ear sebaceous glands which produce mucous membrane with a stratified columnar epithelium w/ goblet cells, providing lubrication b. Inner ear oils that form a surface layer on tear film, reducing evaporation, of surfaces; covers internal eyelid and anterior IV. Summary and lubricating ocular surface (exposed) portion of the sclera Lab 20 – Special Senses IUSM – 2016

I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers a. Fibrous tunic i. Cornea ii. Sclera b. Vascular tunic i. Iris ii. Ciliary body iii. Choroid c. Neural tunic (Retina) 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear b. Inner ear IV. Summary

Fig 23-21, Junqueira, 13th ed. Lab 20 – Special Senses IUSM – 2016 Slide 25: Auditory Meatus, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers ceruminous glands specialized apocrine glands a. Fibrous tunic that aid in production of i. Cornea cerumen (earwax) ii. Sclera b. Vascular tunic i. Iris ii. Ciliary body keratinized stratified iii. Choroid squamous epithelium c. Neural tunic (Retina) auditory 4. Optic Nerve meatus B. Eyelid hair follicle C. Ear 1. General structure 2. Parts a. External ear b. Inner ear the external auditory meatus (acoustic canal) is the air-filled canal that transmits sounds collected by the IV. Summary auricle of the ear to the tympanic membrane (eardrum); the canal is lined with skin and contains large ceruminous glands; the outer (lateral) portion of the canal is supported by elastic cartilage, continuous with the cartilage of the auricle Lab 20 – Special Senses IUSM – 2016 Slide 121: Internal Ear, H&E I. Introduction II. Keywords III. Slides A. Eye 1. General structure 2. Lens 3. Layers vestibular membrane a. Fibrous tunic simple squamous epithelium i. Cornea ii. Sclera stria vascularis b. Vascular tunic vascular epithelium which i. Iris secretes endolymph (high K+) ii. Ciliary body basilar membrane iii. Choroid c. Neural tunic (Retina) vascular CT structure 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear the bony cochlea (Lt. “snail shell”) of the inner ear arises from the vestibule and makes 2 ¾ turns (more are b. Inner ear visible on slide above since guinea pig, not human); the cochlear canal is divided into three compartments: the IV. Summary scala vestibuli and scala tympani which connect at the apex of the cochlea and are filled with perilymph, and the central scala media (cochlear duct) which contains the sensory organ of Corti and is filled with endolymph Lab 20 – Special Senses IUSM – 2016 Slide 121: Internal Ear, H&E I. Introduction II. Keywords III. Slides A. Eye vestibular membrane 1. General structure 2. Lens 3. Layers a. Fibrous tunic i. Cornea tectorial membrane ii. Sclera b. Vascular tunic i. Iris ii. Ciliary body hair cells iii. Choroid c. Neural tunic (Retina) basilar membrane 4. Optic Nerve B. Eyelid C. Ear 1. General structure 2. Parts a. External ear the spiral organ of Corti is responsible for the sensation of sounds; it rests on the basilar membrane within the b. Inner ear scala media; its hair cells (outer and inner) have stereocilia attached to the connective tissue tectorial IV. Summary membrane; sound energy creates a shearing effect between the basilar and tectorial membranes, causing the hair cells (surrounded by endolymph with high K+) to release neurotransmitters to cells in the spiral ganglion Lab 20 – Special Senses IUSM – 2016 pressure waves from the oval window travel scala vestibuli 1 through the scala vestibuli, causing the (perilymph) I. Introduction vestibular membrane to move, and generating II. Keywords pressure waves in the scala media; the scala vestibuli connects to the scala tympani through scala media III. Slides the helicotrema at the apex of the cochlea, (endolymph) A. Eye permitting pressure waves to displace the round high K+ 1. General structure window into to middle ear 2. Lens pressure waves pass in the scala media 3. Layers displace the basilar membrane; composition of the basilar membrane differs according to its a. Fibrous tunic location and affects its displacement: high- i. Cornea frequency sounds displace it near the oval 3 ii. Sclera window while low-frequency sounds travel 5 4 b. Vascular tunic farthest and cause displacement at the most distal portion, near the helicotrema i. Iris 2 ii. Ciliary body scala typmani iii. Choroid (perilymph) c. Neural tunic (Retina) 4. Optic Nerve outer hair cells (3-5 rows), with stereocilia (no kinocilium) in , depolarize when stereocilia are deformed by B. Eyelid tectorial membrane movement of basilar membrane; depolarization causes cells to rapidly C. Ear shorten, pulling down on tectorial membrane which pulls and deforms 1. General structure the stereocilia of the inner hair cells 2. Parts inner hair cells depolarize if pulled toward longest stereocilium, a. External ear releasing neurotransmitters that synapse with bipolar neurons in spiral ganglion; these neurons fire APs down their axons which form b. Inner ear the cochlear branch of CN VIII (vestibulocochlear) IV. Summary CN VIII  cochlear nuclei  sup. olivary nuclei  inf. colliculus  MGN (thalamus)  primary aud. cortex in temporal lobe  “hearing” Lab 20 – Special Senses IUSM – 2016 Common Confusion:

I. Introduction Lip vs. Eyelid II. Keywords III. Slides Lip: movable fold of soft tissue surrounding the mouth A. Eye 1. General structure Look for: (1) internal surface is lined by oral mucosa with non-keratinized stratified squamous epithelium; (2) 2. Lens transition zone between skin and mucosa is more external 3. Layers than in eyelid so skin does not cover anterior surface; (3) a. Fibrous tunic mucous labial salivary glands deep to skeletal muscle i. Cornea ii. Sclera b. Vascular tunic i. Iris Lip ii. Ciliary body iii. Choroid c. Neural tunic (Retina) Eyelid: protective covering for the anterior surface of the eye 4. Optic Nerve Look for: (1) internal surface is lined by conjunctiva with B. Eyelid stratified columnar epithelium and many goblet cells; (2) C. Ear skin extends over anterior surface; (3) sebaceous tarsal glands deep to skeletal muscle; (4) dense fibroelastic CT 1. General structure tarsal plate 2. Parts a. External ear b. Inner ear IV. Summary Eyelid