The Eye 1
Lacrimal apparatus Lacrimal glands Superior and lateral in each eye Produces tears Several small ducts liberate the tear continually Excretory ducts Accessory structures of the eye 2
Lacrimal Apparatus Lacrimal canal Medial in each eye Lacrimal sac Nasolacrimal duct Tears Salt solution Contains lysozyme and antibodies Cleanse, protect, moisten and lubricate the eye ball 3
Accessory structures of the eye Palpebrae Lateral canthus Medial canthus Caruncle – contains sweat and sebaceous glands 4
Accessory structures of the eye Eyelashes Ciliary glands Modified sweat glands between the eyelashes Meibomian or tarsal glands Posterior to the eyelashes. Secrete oil 5
Accessory structures of the eye Sty Acute inflammation of the ciliary or meibomian gland Chalazio Chronic inflammation of the meibomian gland 6
Accessory structures of the eye Conjunctiva Palpebral Ocular or bulbar It is a mucosa that secretes mucus Conjunctivites Inflamation of the conjunctiva Extrinsic muscles of the eye Control eye movement 7
Internal Anatomy of the eye Outer fibrous tunic Dense avascular connective tissue Sclera Cornea Transparent, anterior most portion 8
Internal Anatomy of the eye Middle vascular tunic (uvea) Iris Colored part of the eye Smooth muscle acting as a diaphragm Ciliary body Ciliary muscles – control the shape of the lens Ciliary processes – secretes aqueous humor Suspensory ligaments 9
Internal Anatomy of the eye Choroid Posteriormost part Contain melanin Tapetum lucidum (only in animals) Inner sensory tunic (Retina) Pigmented layer Covers the choroid 10
Internal Anatomy of the eye Neural layer Rods – photoreceptors cells for dim light. Perceives gray tones Cones – photoreceptors cells for color. They need high amount of light Optic disc – blind spot. Emergency of the optic nerve Macula lutea – high concentration of cones. Fovea 11
Internal Anatomy of the eye Lens Held by the suspensory ligaments. Attaches to the ciliary body. Catarats – lens become opaque and hard 12
Internal Anatomy of the eye Anterior segment Aqueous humor – clear fluid formed by the ciliary process. It provides nutrients for the lens and cornea. Scleral venus sinus (canal of Schlemm) – absorbs the aqueous humor Glaucoma – increased intraocular pressure Posterior segment Vitreous humor – helps to keep the retina in place 13
Figure 17.4a, b The Sectional Anatomy of the Eye 14
Microscopic anatomy of the retina Pigmented epithelial layer Located between the choroid and neural layer Neural layer Photoreceptors – rods and cones Bipolar neurons Ganglion neurons 15
Microscopic anatomy of the retina 16
Visual Pathways to the brain Optic nerve Optic chiasma It is the crossing of the fibers of the optic nerve Optic tract Thalamus Optic radiation Visual cortex – located on the occipital lobe 17
Visual Tests and Experiments Blind Spot When the image fall on the optic disc 18
Visual Tests and Experiments Refraction of the light rays Cornea Lens Vitreous humor Accommodation of the lens Near-point accommodation Presbiopia – difficult focus for close vision because of decreased lens elasticity 19
Visual Tests and Experiments Visual acuity Snellen chart Emmetropy Myopia Hyperopia Astigmatism Irregularity in the curvatures of the lens and/or cornea 20
Visual Tests and Experiments Color blindness Three cone types- red, green and blue Binocular vision Three dimensional vision Accuracy of locating objects Depth perception Panoramic vision 21
Visual Tests and Experiments Extrinsic muscles of the eye Convergence Medial eye movements for near vision Keep moving objects focused on the fovea 22
Visual Tests and Experiments Pupillary reflex Photopupillary reflex Constriction of the pupils when the retina is illuminated by a bright light Intrinsic muscles of the eye Accommodation pupillary reflex Change of the pupil diameter for near focus 23
Eye Dissection WHOLE EYE Cornea Sclera Optic nerve Extrinsic muscles 24
Eye Dissection FRONTAL CUT Humors: aqueous, vitreous Lens Ciliary body Iris Pupil Choroid Retina Posterior cavity 25