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Squama
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Squama (or squamous, squame) refers to a structure shaped like a decumbent scale of a fish. More specifically, it can refer to: * Squama frontalis * Squama occipitalis * Squama temporalis, the squamous portion of the temporal bone * Squamous cell In Crustacea, it can refer to the scaphocerite, a scale-like, flattened exopod of the antenna. In the Bivalvia, it refers to a thin, long, concentric imbrication. Squamous epithelium refers to epithelium, e.g. the skin, composed of squamous cells. See also: * Desquamation Desquamation, or peeling skin, is the shedding of dead cells from the outermost layer of skin. The term is . Physiologic desquamation Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temporal Bone
The temporal bone is a paired bone situated at the sides and base of the skull, lateral to the temporal lobe of the cerebral cortex. The temporal bones are overlaid by the sides of the head known as the temples where four of the cranial bones fuse. Each temple is covered by a temporal muscle. The temporal bones house the structures of the ears. The lower seven cranial nerves and the major vessels to and from the brain traverse the temporal bone. Structure The temporal bone consists of four parts—the squamous, mastoid, petrous and tympanic parts. The squamous part is the largest and most superiorly positioned relative to the rest of the bone. The zygomatic process is a long, arched process projecting from the lower region of the squamous part and it articulates with the zygomatic bone. Posteroinferior to the squamous is the mastoid part. Fused with the squamous and mastoid parts and between the sphenoid and occipital bones lies the petrous part, which is shaped li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squama Temporalis
The squamous part of temporal bone, or temporal squama, forms the front and upper part of the temporal bone, and is scale-like, thin, and translucent. Surfaces Its outer surface is smooth and convex; it affords attachment to the temporal muscle, and forms part of the temporal fossa; on its hinder part is a vertical groove for the middle temporal artery. A curved line, the ''temporal line'', or ''supramastoid crest'', runs backward and upward across its posterior part; it serves for the attachment of the temporal fascia, and limits the origin of the temporalis muscle. The boundary between the squamous part and the mastoid portion of the bone, as indicated by traces of the original suture, lies about 1 cm. below this line. Projecting from the lower part of the squamous part is a long, arched process, the '' zygomatic process''. This process is at first directed lateralward, its two surfaces looking upward and downward; it then appears as if twisted inward upon itself, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scale (zoology)
In zoology, a scale (; ) is a small rigid plate (animal anatomy), plate made out of keratin that grows out of Vertebrate animals' skin to provide protection. In lepidopterans (butterflies and moths), scales are plates on the surface of the insect wing, made out of chitin instead of keratin, and provide coloration. Scales are quite common and have evolved multiple times through convergent evolution, with varying structure and function. Scales are generally classified as part of an organism's integumentary system. There are various types of scales according to the shape and class (biology), class of an animal. Fish scales Fish scales are skin, dermally derived, specifically in the mesoderm. This fact distinguishes them from reptile scales paleontologically. Genetically, the same genes involved in tooth and hair development in mammals are also involved in scale development. File:Ganoid scales.png, Ganoid scales on a carboniferous fish ''Amblypterus striatus'' File:Denticules cutanĂ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squama Frontalis
The squamous part of the frontal bone is the superior (approximately two thirds) portion when viewed in standard anatomical orientation. There are two surfaces of the squamous part of the frontal bone: the external surface, and the internal surface. External surface The external surface is convex and usually exhibits, in the lower part of the middle line, the remains of the frontal suture; in infancy this suture divides the frontal bone into two and later fuses. A condition where fusion has not taken place, may persist throughout life and is referred to as a ''metopic suture''. On either side of this suture, about 3 cm. above the supraorbital margin, is a rounded elevation, the frontal eminence (tuber frontale). These eminences vary in size in different individuals, are occasionally unsymmetrical, and are especially prominent in young skulls; the surface of the bone above them is smooth, and covered by the epicranial aponeurosis. Below the frontal eminences, and separated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squama Occipitalis
The squamous part of occipital bone is situated above and behind the foramen magnum, and is curved from above downward and from side to side. External surface The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance and inion. Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the epicranial aponeurosis is attached. The lower is termed the superior nuchal line. That area of the squamous part, which lies above the highest nuchal lines is named the occipital plane ''(planum occipitale)'' and is covered by the '' occipitalis muscle''. That below, termed the nuchal plane, is rough and irregular for the attachment of several muscles. From the external occipital protuberance, an often faintly marked ridge or crest, the median nuchal line, descends to the forame ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can be grouped into the more basal (phylogenetics), basal jawless fish and the more common jawed fish, the latter including all extant taxon, living cartilaginous fish, cartilaginous and bony fish, as well as the extinct placoderms and acanthodians. In a break to the long tradition of grouping all fish into a single Class (biology), class (Pisces), modern phylogenetics views fish as a paraphyletic group. Most fish are ectotherm, cold-blooded, their body temperature varying with the surrounding water, though some large nekton, active swimmers like white shark and tuna can hold a higher core temperature. Many fish can communication in aquatic animals#Acoustic, communicate acoustically with each other, such as during courtship displays. The stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squamous Cell
Epithelium or epithelial tissue is a thin, continuous, protective layer of Cell (biology), cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial (Mesothelium, mesothelial) tissues line the outer surfaces of many internal organ (anatomy), organs, the corresponding inner surfaces of body cavities, and the inner surfaces of blood vessels. Epithelial tissue is one of the four basic types of animal Tissue (biology), tissue, along with connective tissue, muscle tissue and nervous tissue. These tissues also lack blood or lymph supply. The tissue is supplied by nerves. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either simple squamous, simple columnar, or simple cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacea
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese spider ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod Leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip (anatomy), hip, : ''coxae''), ''trochanter'', ''femur'' (: ''femora''), ''tibia'' (: ''tibiae''), ''tarsus'' (: ''tarsi''), ''ischium'' (: ''ischia''), ''metatarsus'', ''carpus'', ''dactylus'' (meaning finger), ''patella'' (: ''patellae''). Homology (biology), Homologies of leg segments between groups are difficult to prove and are the source of much argument. Some authors posit up to eleven segments per leg for the most recent common ancestor of Neontology, extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, and that other events, such as successive loss of function of a Homeobox, ''Hox''-gene, could result in Parallel evolution, parallel gains of leg segments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivalvia
Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-bivalve shell, shells known as valve (mollusc), valves. As a group, bivalves have no head and lack some typical molluscan organs such as the radula and the odontophore. Their gills have evolved into ctenidium (mollusc), ctenidia, specialised organs for feeding and breathing. Common bivalves include clams, oysters, Cockle (bivalve), cockles, mussels, scallops, and numerous other family (biology), families that live in saltwater, as well as a number of families that live in freshwater. Majority of the class are benthic filter feeders that bury themselves in sediment, where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelium
Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of many internal organs, the corresponding inner surfaces of body cavities, and the inner surfaces of blood vessels. Epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. These tissues also lack blood or lymph supply. The tissue is supplied by nerves. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either simple squamous, simple columnar, or simple cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
