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Toenail
A nail is a protective plate characteristically found at the tip of the digits (fingers and toes) of all primates, corresponding to the claws in other tetrapod animals. Fingernails and toenails are made of a tough rigid protein called alpha-keratin, a polymer also found in the claws, hooves, and horns of vertebrates. Structure The nail consists of the nail plate, the nail matrix and the nail bed below it, and the grooves surrounding it. Parts of the nail The nail matrix is the active tissue (or germinal matrix) that generates cells. The cells harden as they move outward from the nail root to the nail plate. The nail matrix is also known as the ''matrix unguis'', keratogenous membrane, or onychostroma. It is the part of the nail bed that is beneath the nail and contains nerves, lymph, and blood vessels. The matrix produces cells that become the nail plate. The width and thickness of the nail plate is determined by the size, length, and thickness of the matrix, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunula (anatomy)
The lunula (: lunulae; ) is the crescent-shaped whitish area of the bed of a fingernail or toenail. In humans, it appears by week 14 of gestation, and has a primary structural role in defining the free edge of the distal nail plate (the part of the nail that grows outward). Appearance The lunula is located at the end of the nail that is closest to the skin of the finger, but it still lies under the nail. It is not actually white but only appears so when it is seen through the nail. Outlining the nail matrix, the lunula is a very delicate part of the nail structure. If one damages the lunula, the nail will be permanently deformed. Even when the totality of the nail is removed, the lunula remains in place and is similar in appearance to another smaller fingernail embedded in the nail bed. In most cases, it is half-moon-shaped and has unique histologic features. Examinations concluded that the lunula is an area of loose dermis with lesser developed collagen bundles. It appears w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primate
Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers and simians (monkeys and apes). Primates arose 74–63 million years ago first from small terrestrial animal, terrestrial mammals, which adapted for life in tropical forests: many primate characteristics represent adaptations to the challenging environment among Canopy (biology), tree tops, including large brain sizes, binocular vision, color vision, Animal communication, vocalizations, shoulder girdles allowing a large degree of movement in the upper limbs, and opposable thumbs (in most but not all) that enable better grasping and dexterity. Primates range in size from Madame Berthe's mouse lemur, which weighs , to the eastern gorilla, weighing over . There are 376–524 species of living primates, depending on which classification is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paronychia
Paronychia is an inflammation of the skin around the nail, often due to bacteria or fungi. Its sudden (acute) occurrence is usually due to the bacterium ''Staphylococcus aureus''. Gradual (chronic) occurrences are typically caused by fungi, commonly '' Candida albicans''. Risk factors for paronychia include frequent hand washing and trauma to the cuticle, such as from chronic nail biting or hangnails. Treatment typically involves antibiotics for bacterial infections and antifungals for fungal infections. If there is pus formation, incision and drainage may be necessary. Paronychia is commonly mistakenly used interchangeably with herpetic whitlow or felon, which are distinct conditions. Etymology The term paronychia is from the from ''para'', "around", ''onyx'', "nail" and the noun suffix '' -ia''. Signs and symptoms The index and middle fingers are most commonly affected and may present with redness, swelling and pain. Pus or discharge may be present. Fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuticle
A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structure, function, and chemical composition. Human anatomy In human anatomy, "cuticle" can refer to several structures, but it is used in general parlance, and even by medical professionals, to refer to the thickened layer of skin surrounding fingernails and toenails (the eponychium), and to refer to the superficial layer of overlapping cells covering the hair shaft ( cuticula pili), consisting of dead cells, that locks the hair into its follicle. It can also be used as a synonym for the epidermis, the outer layer of skin. Cuticle of invertebrates In zoology, the invertebrate cuticle or cuticula is a multi-layered structure outside the epidermis of many invertebrates, notably arthropods and roundworms, in which it forms an exoskeleton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hooves, and the outer layer of skin in vertebrates. Keratin also protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong mineralization (biology), unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. Excessive keratinization participate in fortification of certain tissues such as in horns of cattle and rhinos, and armadillos' osteoderm. The only other biology, biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin comes in two types: the primitive, softer forms found in all vertebrates and the harder, derived forms fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrix (biology)
In biology, matrix (: matrices) is the material (or tissue) in between a eukaryotic organism's cells. The structure of connective tissues is an extracellular matrix. Fingernails and toenails grow from matrices. It is found in various connective tissues. It serves as a jelly-like structure instead of cytoplasm in connective tissue. Tissue matrices Extracellular matrix (ECM) The main ingredients of the extracellular matrix are glycoproteins secreted by the cells. The most abundant glycoprotein in the ECM of most animal cells is collagen, which forms strong fibers outside the cells. In fact, collagen accounts for about 40% of the total protein in the human body. The collagen fibers are embedded in a network woven from proteoglycans. A proteoglycan molecule consists of a small core protein with many carbohydrate chains covalently attached, so that it may be up to 95% carbohydrate. Large proteoglycan complexes can form when hundreds of proteoglycans become noncovalently attached ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integumentary System
The integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the skin and its appendages, which act as a physical barrier between the external environment and the internal environment that it serves to protect and maintain the body of the animal. Mainly it is the body's outer skin. The integumentary system includes skin, hair, scales, feathers, hooves, claws, and nails. It has a variety of additional functions: it may serve to maintain water balance, protect the deeper tissues, excrete wastes, and regulate body temperature, and is the attachment site for sensory receptors which detect pain, sensation, pressure, and temperature. Structure Skin The skin is one of the largest organs of the body. In humans, it accounts for about 12 to 15 percent of total body weight and covers 1.5 to 2 m2 of surface area. The skin (integument) is a composite organ, made up of at least two major layers of tissue: the epidermis and the dermis. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Vessel
Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (biology), body. They also take waste and carbon dioxide away from the tissues. Some tissues such as cartilage, epithelium, and the lens (anatomy), lens and cornea of the eye are not supplied with blood vessels and are termed ''avascular''. There are five types of blood vessels: the arteries, which carry the blood away from the heart; the arterioles; the capillaries, where the exchange of water and chemicals between the blood and the tissues occurs; the venules; and the veins, which carry blood from the capillaries back towards the heart. The word ''vascular'', is derived from the Latin ''vas'', meaning ''vessel'', and is mostly used in relation to blood vessels. Etymology * artery – late Middle English; from Latin ''arteria'', from Gree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phalanx (anatomy)
The phalanges (: phalanx ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. Structure The phalanges are the bones that make up the fingers of the hand and the toes of the foot. There are 56 phalanges in the human body, with fourteen on each hand and foot. Three phalanges are present on each finger and toe, with the exception of the thumb and big toe, which possess only two. The middle and far phalanges of the fifth toes are often fused together (symphalangism). The phalanges of the hand are commonly known as the finger bones. The phalanges of the foot differ from the hand in that they are often shorter and more compressed, especially in the proximal phalanges, those closest to the torso. A phalanx is named according to whether it is proximal, middle, or distal and its associated finger or toe. The proximal phalan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomical Terms Of Location
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, '' Termi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phalanx Bone
The phalanges (: phalanx ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. Structure The phalanges are the bones that make up the fingers of the hand and the toes of the foot. There are 56 phalanges in the human body, with fourteen on each hand and foot. Three phalanges are present on each finger and toe, with the exception of the thumb and big toe, which possess only two. The middle and far phalanges of the fifth toes are often fused together (symphalangism). The phalanges of the hand are commonly known as the finger bones. The phalanges of the foot differ from the hand in that they are often shorter and more compressed, especially in the proximal phalanges, those closest to the torso. A phalanx is named according to whether it is proximal, middle, or distal and its associated finger or toe. The proximal phalange ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyponychium
The hyponychium () is the area of epithelium, particularly the thickened portion, underlying the free edge of the nail plate on the nail. Its proximal border is immediately distal to distal limit of nail bed—a.k.a. the onychodermal band (the line along the interface of the nail bed and the nail plate). Its distal border the free edge of the nail plate—or where that edge would project downwards onto the epidermis. It is sometimes called "the quick" (in its archaic meaning of "living"), as in the phrase cut to the quick. See also * Eponychium In human anatomy, the eponychium is the thickened layer of skin at the base of the fingernails and toenails. It can also be called the medial or proximal nail fold. Its function is to protect the area between the nail and epidermis from exposure ... References Nail anatomy {{anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
