Three main accessory eye structures Rating: 4,5/10 103reviews
The eye is a complex organ that is essential for vision, and it is supported by several accessory structures that help it function properly. These structures include the eyebrows, eyelashes, and eyelids.
The eyebrows are a pair of thick, arched hairs that grow above the eyes. They help to keep sweat and other debris from entering the eyes, and they also play a role in facial expression. The eyebrows are made up of long, coarse hairs that are held in place by a layer of skin called the brow bone. They can be shaped and groomed using tweezers or other grooming tools.
The eyelashes are a row of short, curved hairs that grow along the edge of the eyelids. Like the eyebrows, they help to keep foreign substances out of the eyes and protect them from damage. The eyelashes are made up of fine, soft hairs that are held in place by a thin layer of skin called the eyelid margin. They can be enhanced with the use of mascara or false eyelashes.
The eyelids are a pair of skin folds that cover and protect the eyes. They consist of two layers of skin: the outer layer, called the skin layer, and the inner layer, called the conjunctiva. The eyelids contain a number of glands that produce oils and mucus to keep the eyes moist and lubricated. They also contain muscles that help to open and close the eyelids.
In conclusion, the eyebrows, eyelashes, and eyelids are three important accessory structures of the eye that play important roles in protecting and maintaining the health of the eye. They help to keep foreign substances out of the eye, maintain moisture and lubrication, and enable us to express a range of emotions through facial expressions.
The Structure of the Eye and the Functions of these Accessory Structures.
The caruncle is the small, pinkish portion of the innermost corner of the eye that contains oil and sweat glands and conjunctival tissue. The cones in this area are narrower than in other parts of the retina, allowing for more cones per unit area. Contraction of the ciliary muscles relaxes the fibrous strands in the ciliary zonule and allows the lens to become more spherical in shape. The inferior tarsus tarsus inferior; inferior tarsal plate , the smaller, is thin, elliptical in form, and has a vertical diameter of about 5 mm. Nearsightedness myopia is blurred vision caused by light rays being incorrectly focused anterior to the Retina.
The Accessory Organs of the Eye
Lockwood, Journal of Anatomy and Physiology, vol. The medial angles of the two plates end at the lacus lacrimalis, and are attached to the frontal process of the maxilla by the medial palpebral ligament page 381. At the angles they are dilated into ampullæ; their walls are dense in structure and their mucous lining is covered by stratified squamous epithelium, placed on a basement membrane. The mechanism of vision may be summarized as follows figure 9. External limiting membrane ELM : The ELM is not a true membrane, but it is a region of zonulae adherents between the photoreceptor cells and Muller cells. The middle lamella, largely made up of non-striped muscular fibers, is inserted into the upper margin of the superior tarsus, while the deepest lamella blends with an expansion from the sheath of the Rectus superior and with it is attached to the superior fornix of the conjunctiva. The skeletal system provides our body with shape and stability, as well as the protection of internal organs.
What are the accessory structures? [Expert Guide!]
Between the two heads of the Rectus lateralis is a narrow interval, through which pass the two divisions of the oculomotor nerve, the nasociliary nerve, the abducent nerve, and the ophthalmic vein. If any two neighboring Recti of one eye act together they carry the globe of the eye in the diagonal of these directions, viz. It is composed of 206 bones that connect to each other via joints. Inner nuclear layer: This layer contains the cell bodies of the intermediate neurons bipolar, horizontal, and amacrine cells and Muller cells. The optics of the eye cause the image to be inverted on the retina, as shown in figure 9.
Accessory Structures of the Eye
An antibacterial enzyme lysozyme in tears helps to reduce the chance of eye infections. Müller, may be seen bridging across the inferior orbital fissure. Tear film: The tear film consists of aqueous, mucus, and oily secretions. The collagen bundles are organized into extremely regular layers. The Lacrimal Gland glandula lacrimalis. In such cases, the ciliary muscles in your eyes relax. As they probably check the actions of these two Recti they have been named the medial and lateral check ligaments.
The Eye: Three Main Parts: [Essay Example], 316 words GradesFixer
The Levator palpebræ superioris arises from the under surface of the small wing of the sphenoid, above and in front of the optic foramen, from which it is separated by the origin of the Rectus superior. A few slender hairs are attached to its surface. It is loosely connected to the bones and can be readily separated from them. The upper eyelid has, in addition, the aponeurosis of the Levator palpebræ superioris 17 The integument is extremely thin, and continuous at the margins of the eyelids with the conjunctiva. Rods are the photoreceptor cells specialized for perceiving dim light, while cones are specialized for perceiving bright light and color. After completing his doctoral studies, he decided to start "ScienceOxygen" as a way to share his passion for science with others and to provide an accessible and engaging resource for those interested in learning about the latest scientific discoveries.
What are the three main eye structures that contribute to the formation of tears and lubrication of the eyeball?
This upper band is sometimes termed the superior tendon of Lockwood. Accessory glands: Apocrine glands of Moll, meibomian glands, lacrimal glands. The lacrimal gland tear gland is located at the upper, outer corner of each eye. The tarsi tarsal plates Fig. The pupil is constricted in bright light and is dilated in dim light. It is a single layer of simple squamous to simple cuboidal cells. The Rectus medialis is the broadest, the Rectus lateralis the longest, and the Rectus superior the thinnest and narrowest.
Ch. 18 Special Senses Worksheet Flashcards
What are the accessory structures of the eye quizlet? It is oval in form and measures from 12 to 15 mm. They are imbedded in grooves in the inner surfaces of the tarsi, and correspond in length with the breadth of these plates; they are, consequently, longer in the upper than in the lower eyelid. Its inner surface is smooth, and is separated from the outer surface of the sclera by the periscleral lymph space. Anatomy and Physiology The eyelid provides protection to the cornea, disperses the tear film across the ocular surface, removes debris, and plays an important role in producing the tear film and providing immunologic protection of the cornea. The tendon is reflected backward, lateralward, and downward beneath the Rectus superior to the lateral part of the bulb of the eye, and is inserted into the sclera, behind the equator of the eyeball, the insertion of the muscle lying between the Rectus superior and Rectus lateralis.
What are the accessory organs of the eye and their functions?
It envelops the entire lens, and the underlying epithelial cells are unable to desquamate. The conjunctiva is a clear mucous membrane that lines the inner surface of the eyelids and the outer surface of the eye. It is a natural result of aging. The collagen is covered by the basement membrane of the choroid on one side and the basement membrane of the retinal pigment epithelium on the other side. The Eyelids palpebræ are two thin, movable folds, placed in front of the eye, protecting it from injury by their closure. The expansions from the sheaths of the Recti lateralis and medialis are strong, especially that from the latter muscle, and are attached to the lacrimal and zygomatic bones respectively. A deficiency of vitamin A mayresult in an insufficient amount of rhodopsin in the rods, which, in turn, may lead to night Although the light-sensitive pigments are different in cones, they function in a similar way to rhodopsin.