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Special Senses Week 12 Exterior Eye Anatomy 1? 3? 2? Orbicularis oculi muscle (Under eyebrow) Sclera Cornea Conjunctiva Transparent mucus membrane Covers only the white of the eye -Produces mucus which prevents the eyes from drying out Exterior Eye Anatomy (palpabrae) Sebaceous and sweat gland (palpabrae) Exterior Eye Anatomy Tears are a dilute saline solution that cleans and protects, moistens and lubricates the eye Pin holes If you have a cold, the nasal mucosa becomes inflamed. No tear drainage into nose. Watery eyes Extrinsic Eye Muscles A. B. C. D. E. F. G. Lateral rectus (abducens) Inferior rectus Superior rectus Inferior oblique: up and lateral Superior oblique: down and lateral (trochlear) Levator palpebrae superioris Medial rectus (not shown) Objective 1: Structures of the Human Eye Pushing the Limits: Sight, video 3 Internal Eye Three concentric tunics (layers) of the eye: • Outer fibrous tunic • Middle vascular tunic • Inner sensory tunic Internal Eye Three concentric tunics (layers) of the eye: • Outer fibrous tunic – sclera, cornea • Middle vascular tunic • Inner sensory tunic Sclera (white of the eye) • • Lens Cornea • • • • Window Lets light enter eye No blood vessels Can be transplanted easily Protects the eye Attaches eye muscles Internal Eye Three concentric tunics (layers) of the eye: • Outer fibrous tunic • Middle vascular tunic – choroid, ciliary body (ciliary muscle & process), iris • Inner sensory tunic Ciliary Body Sclera Controls lens shape Choroid Ciliary muscle Ciliary process Suspensory ligaments Makes aqueous humor Iris Modulates pupil size Pupil Allows light to enter eye Cornea Lens Blood vessel rich, dark brown membrane Pupil dilation & constriction Internal Eye Three concentric tunics (layers) of the eye: • Outer fibrous tunic-connective tissue • Middle vascular tunic • Inner sensory tunic - retina Sclera Choroid Retina Optic Nerve (CN II) Absorb light and prevent it from scattering Light Retina • • Rods: • Night vision • Peripheral vision Cones: • Visual acuity (sharpness) • Color vision Human Retina Retinal ganglion cells Bipolar cell nuclei Rods & Cones Nuclei of rods & cones Outer segments of rods & cones Pigmented epithelial layer Vascular Tunic Posterior Wall (fundus) of the Eye Retina Macula lutea Fovea centralis (all cones) Optic disk (blind spot) (no rods and cones) Optic nerve The OPTIC DISC is the region were: • the optic nerve exits the eye •The central artery and vein of the retina enter and exit the eye •There are no photoreceptors, the “blind spot” Ophthalmoscope View Fovea centralis & Macula lutea The macula lutea is an oval region lateral to the optic disc, at it’s center lies the fovea centralis, the area of greatest cone density in the retina. Segments of the Eye Vitreous humor Anterior segment: area in front of the lens, filled with aqueous humor (Constantly generated and removed) Posterior segment: area behind the lens, filled with vitreous humor (made once for life) Anterior Segment Anterior chamber: between the cornea and iris Posterior chamber: between iris and lens • • • Aqueous humor made by capillaries in ciliary process Drops into posterior chamber Passes to anterior chamber Scleral venous sinus (Canal of Schlemm) Suspensory ligaments Objective 4: Ear Anatomy 1 (the rim) 2 3 External Auditory Meatus Middle ear: air filled (links with nose!) Inner ear Vestibular & Cochlear nerves join to become the Vestibulocochlear Nerve (CN VIII) Cochlear nerve Cochlea S.V. S.T. Identify given structures from models and slides Cochlea Stapes Cochlea, cs (Endoymph) (Perilymph) (Perilymph) Cochlea histology Cochlea Endolymph Perilymph = CSF Endolymph = intracellular fluid Hearing physiology Primary auditory cortex in temporal lobe Midbrain Medulla Vibrations Vibrations Vestibulocochlear Nerve (VIII) Balance & Equilibrium Inner Ear Vestibule – utricle & saccule Static equilibrium Responds to changes in linear movement (vertical & horizontal) Monitor head position, posture Semicircular Canals - ampulla Dynamic equilibrium Responds to changes in rotational movement Balance Objective 2: Cow Eye Dissection Identify all external and internal structures listed! lens Follow the directions given in the Lab Manual! retina Tapetum lucidum Iridescent portion (retina removed) Not present in humans Objectives 3 & 5: Experiments E HN PTXZ UZDTF D F N P T H Lab Activity: • Dissect cow’s eye • Perform visual, auditory & balance experiments and analyze On the Practical: • Identify the macro-structures of the eye from models and the cow eye • Identify the macro-structures of the ear from models • Identify the microscopic structures of the retina and cochlea