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01~感觉器官(Sensory organs).ppt
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    The Sensory Organs

    山东大学医学院解剖教研室

    李振华

    The Sensory Organs

    Sensory organs include the receptors and accessory organs. The receptors may be divided into three kinds:

    * The exteroceptors 外感受器: receive stimuli such as touch, temperature, pain, light and sound from the external environment

    * The interoceptors 内感受器: pick up information about internal environment

    * The proprioceptors 本体感受器: receive stimuli from muscles, tendons, joints and ligaments

    The Visual Organ 视器

    Composition: eyeball and accessory organs of eye

    Shape of eyeball

    * Has anterior and posterior poles

    * Equator 赤道: an imaginary line encircling the eyeball, midway between anterior and posterior poles

    * Axis of eyeball 眼轴: a line joining the two poles

    * Optic axis 视轴: a line joining the center of the pupil to the fovea centralis

    Walls of eyeball

    Fibrous tunic of eyeball (outer)

    * Cornea 角膜: anterior 1/6, a nonvascular, transparent portion, richly supplied by nerves; because it is curved, the cornea helps focus light

    * Sclera 巩膜 (white of eye, opaque portion):

    * posterior 5/6, consisting of fibrous connective tissue that forms a tough protective covering for eyeball,* Contains sinus venosus sclerae 巩膜静脉窦which lies beneath the junction of cornea and sclera

    Vascular tunic of eyeball (middle)

    * Iris 虹膜

    * Thin contractile membrane anterior to ciliary body, with a central opening, the pupil 瞳孔

    * Contains sphincter pupillae 瞳孔括约肌(circular fibers) and dilator pupillae 瞳孔开大肌 (radial fibers)

    * Cornea and iris meet to form the iridocorneal angle 虹膜角膜角

    * Cilliary body 睫状体

    * Body a ring-shaped thickening anterior to equator, containing smooth muscle fibers called ciliary muscle 睫状肌

    * Ciliary processes 睫状突:a series of some 60~80 projections producing aqueous humor

    * Ciliary ring 睫状环

    * Choroid 脉络膜

    * Thin, highly vascular in posterior 2/3 of eye

    * Contains brown pigmented cells and dense capillary plexus

    Retina 视网膜

    * Pars caeca retinae视网膜盲部

    * Pars iridica retinae 视网膜虹膜部

    * Pars ciliaris retinae 视网膜睫状体部

    * Pars optica retinae视网膜视部

    * Lines the choroidsComposed of two layers

    * An outer pigment cell layer

    * Inner neural layer (four layers)

    * The fourth layer consists photoreceptor cells

    * Cone cells 视锥细胞are color receptors that function best during the day

    * Rod cells 视杆细胞are dark-light receptors that function best at night and in dim light

    * The third layer consists of bipolar neurons 双极细胞

    * The second layer is formed ganglion cells 节细胞, whose axons form optic nerve

    * The first layer consists of nerve axons that collect at the optic disk and pass through the sclera to form the optic nerve

    * Optic disc 视神经盘 (blind spot), located medial to posterior pole of eye, and consists of optic nerve fibers and central artery of retina

    * Macula lutea 黄斑

    * Lies lateral about 3.5 mm to optic disc, a shallow depression, it is completely free of blood vessels and is yellowish in color

    * Fovea centralis 中央凹, aera of greatest visual acuity (concentration of cones), at its center

    * The pigmentted layer absorbs light that passes completely through the anterior layer, preventing backscatter (blurring of vision)

    Contents of eyeball

    Aqueous humor 房水

    Chamber of eye 眼房- lies between cornea and lens, and divided by iris into anterior and posterior chambers

    Aqueous humor 房水

    * A clear watery fluid that fills chamber of eye

    * Continuouslysecreted by ciliary body into posterior chamber

    * Passesthrough pupil into anterior chamber

    * Then it filters though iridocorneal angle into sinus venosus sclerae, this sinus drains via anterior ciliary veins into ophthalmic veins

    Production and circulation of aqueous humor

    Lens 晶状体

    * Transparent biconvex structure, covered by an elastic transparent capsule

    * Located between iris and vitreous body, and suspended behind pupil by ciliary zonule 睫状小带

    * Shape changed by the ciliary muscle: for near vision, the ciliary muscle contracts and the lens rounds up, while for distant vision the lens flattens out, so that the eye may be focused on distant objects

    Vitreous body 玻璃体

    * Consists of colorless, transparent jelly-like substance in which there is a meshwork of fine fibrils, occupies the vitreous chamber, the space between lens and retina

    * Helps maintain the shape of eyeball and supports the retina

    Refractive media of eye折光装置

    Bend entering light waves and focus them on the retina

    * Cornea

    * Aqueous humor

    * Lens

    * Vitreous body

    Accessory organs of eye 眼副器

    Eyelids 眼睑

    (from without inwards )

    * Skin, extremely thin

    * Subcutaneous areola tissue, loose and delicate

    * Muscular layer: orbicularis oculi

    * Tarsus 睑板, formed by dense connective tissue in which the tarsal glands睑板腺embedded

    * Lined by palpebral conjunctiva 睑结膜

    Function: to protect, open, and close eye

    Conjunctiva 结膜

    * Three parts

    * Palpebral conjunctiva睑结膜: lining inner surface of eyelids

    * Bulbar conjunctiva 球结膜: lining anterior part of sclera, up to corneal margin

    * Conjuntival fornix 结膜穹(superior and inferior): line of reflection of bulbar and palpebral conjunctiva

    * Conjunctival sac 结膜囊

    Lacrimal apparatus 泪器

    Lacrimal gland 泪腺

    * Oval 2-cm, occupies fossa for lacrimal gland

    * Ducts (6~10 in number): empty into anterior region of superior fornix of conjunctiva

    * Secrets tears, which move across eyeball to medial angle,protect and moisten eye

    Lacrimal passages 泪道

    * Lacrimal puncta 泪点 opening to lacrimal ductules, one on each eylid margin near medial angle

    * Lacrimal ductules 泪小管: one in each lid, pass medially, join and enter lacrimal sac

    * Lacrimal sac 泪囊 within fossa for lacrimal sac, opening into nasolacrimal duct......（后略) ......