Extensor carpi radialis brevis muscle
In human anatomy, extensor carpi radialis brevis is a muscle in the forearm that acts to extend and abduct the wrist. It is shorter and thicker than its namesake extensor carpi radialis longus which can be found above the proximal end of the extensor carpi radialis brevis, it arises by the common extensor tendon. The fibres end at the middle of the forearm in the form of a flat tendon, connected with that of the extensor carpi radialis longus, accompanies it to the wrist. Under the extensor retinaculum the tendon lies on the back of the radius in a shallow groove, to the ulnar side of that which lodges the tendon of the extensor carpi radialis longus, separated from it by a faint ridge. Like all the muscles in the posterior forearm, ECR brevis is supplied by a branch of the radial nerve, it is an extensor, an abductor of the hand at the wrist joint. That is, it serves to manipulate the wrist so that the hand moves away from the palm and towards the thumb; the muscle, like all extensors of the forearm, can be strengthened by exercise that resist its extension.
A wrist roller can reverse wrist curls with dumbbells can be performed. This article incorporates text in the public domain from page 452 of the 20th edition of Gray's Anatomy
Birds known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, a strong yet lightweight skeleton. Birds range in size from the 5 cm bee hummingbird to the 2.75 m ostrich. They rank as the world's most numerically-successful class of tetrapods, with ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are less developed depending on the species. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites and diverse endemic island species of birds; the digestive and respiratory systems of birds are uniquely adapted for flight. Some bird species of aquatic environments seabirds and some waterbirds, have further evolved for swimming; the fossil record demonstrates that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs.
The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of powered flight, many retained primitive characteristics like toothy jaws in place of beaks, long bony tails. DNA-based evidence finds that birds diversified around the time of the Cretaceous–Palaeogene extinction event 66 million years ago, which killed off the pterosaurs and all the non-avian dinosaur lineages, but birds those in the southern continents, survived this event and migrated to other parts of the world while diversifying during periods of global cooling. This makes them the sole surviving dinosaurs according to cladistics; some birds corvids and parrots, are among the most intelligent animals. Many species annually migrate great distances. Birds are social, communicating with visual signals and bird songs, participating in such social behaviours as cooperative breeding and hunting and mobbing of predators.
The vast majority of bird species are monogamous for one breeding season at a time, sometimes for years, but for life. Other species have breeding systems that are polygynous or polyandrous. Birds produce offspring by laying eggs, they are laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching; some birds, such as hens, lay eggs when not fertilised, though unfertilised eggs do not produce offspring. Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs and feathers. Songbirds and other species are popular as pets. Guano is harvested for use as a fertiliser. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them.
Recreational birdwatching is an important part of the ecotourism industry. The first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae. Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system in use. Birds are categorised as the biological class Aves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda. Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica. However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the crown group of the set of modern birds; this was done by excluding most groups known only from fossils, assigning them, instead, to the Avialae, in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.
Gauthier identified four different definitions for the same biological name "Aves", a problem. Gauthier proposed to reserve the term Aves only for the crown group consisting of the last common ancestor of all living birds and all of its descendants, which corresponds to meaning number 4 below, he assigned other names to the other groups. Aves can mean all archosaurs closer to birds than to crocodiles Aves can mean those advanced archosaurs with feathers Aves can mean those feathered dinosaurs that fly Aves can mean the last common ancestor of all the living birds and all of its descendants (a "c
The carpometacarpal joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones. The CMC joint of the thumb or the first CMC joint known as the trapeziometacarpal joint, differs from the other four CMC joints and is therefore described separately; the carpometacarpal joint of the thumb known as the first carpometacarpal joint, or the trapeziometacarpal joint because it connects the trapezium to the first metacarpal bone, plays an irreplaceable role in the normal functioning of the thumb. The most important joint connecting the wrist to the metacarpus, osteoarthritis of the TMC is a disabling condition. Pronation-supination of the first metacarpal is important for the action of opposition; the movements of the first CMC are limited by the shape of the joint, by the capsulo-ligamentous complex surrounding the joint, by the balance among involved muscles. If the first metacarpal fails to sit well'on the saddle', for example because of hypoplasia, the first CMC joint tends to be subluxated towards the radius.
The capsule is sufficiently slack to allow a wide range of movements and a distraction of 3 mm, while reinforcing ligaments and tendons give stability to the joint. It is thicker on its dorsal side than on the other; the first carpometacarpal joint is a frequent site of osteoarthritis in postmenopausal women. The description of the number and names of the ligaments of the first CMC varies in anatomical literature. Imaeda et al. 1993 describe three intracapsular and two extracapsular ligaments to be most important in stabilizing the thumb: Anterior oblique ligament A strong and intracapsular ligament originating on the palmar tubercle of the trapezium to be inserted on the palmar tubercle of the first metacarpal. It is taut in abduction and pronation, has been reported to have an important retaining function and to be elongated or absent in CMC joint arthritis. Ulnar collateral ligament An extracapsular ligament, the UCL is located ulnarly to the AOL, it has its origin on the flexor retinaculum and is inserted on the ulnopalmar tubercle of the first metacarpal.
It is taut in abduction and pronation, found elongated in connection to CMC joint arthritis. The importance ascribed to the UCL varies among researchers. First intermetacarpal ligament Connecting the bases of the second and first metacarpals, this ligament inserts onto the ulnopalmar tubercle of the first metacarpal where its fibers intermingle with those of the UCL, it is taut in abduction and supination. It has been reported to be the most important restraining structure of the first CMC joint by several researchers; some consider it too weak to be able to stabilize the joint by itself, yet accept that together with the UCL it represents an important restraining structure. Posterior oblique ligament An intracapsular ligament stretching from the dorsoulnar side of the trapezium to the ulno-palmar tubercle of the first metacarpal. Not considered an important ligament to the first CMC joint, it tightens during forced adduction and radial abduction. Dorsoradial ligament Like the previous ligament, the DRL is not considered important to the first CMC.
It connects the dorsal sides of the first metacarpal. Early, anatomically correct drawings of the ligaments of the first carpometacarpal joints where produced by Weitbrecht 1742. In this articulation the movements permitted are flexion and extension in the plane of the palm of the hand and adduction in a plane at right angles to the palm and opposition, it is by the movement of opposition that the tip of the thumb is brought into contact with the volar surfaces of the flexed fingers. This movement is effected through the medium of a small sloping facet on the anterior lip of the saddle-shaped articular surface of the greater multangular; the flexor muscles pull the corresponding part of the articular surface of the metacarpal bone on to this facet, the movement of opposition is carried out by the adductors. Flexion of this joint is produced by the flexor pollicis longus and brevis, assisted by the opponens pollicis and the adductor pollicis. Extension is effected by the abductor pollicis longus, assisted by the extensores pollicis longus and brevis.
Adduction is carried out by the adductor. Range of motion for the first CMC is 53° of flexion/extension, 42° of abduction/adduction, 17° of rotation. Planes and axes of movementsThe thumb's MP and CMC joints abduct and adduct in a plane perpendicular to the palm, a movement referred to as "palmar abduction." The same joints flex and extend in a plane parallel to the palm referred to as "radial abduction," because the thumb moves toward the hand's radial side. Abduction and adduction occur around an antero-posterior axis, while flexion and extension occur around a lateral axis. For ease of orientation, the thumbnail can be considered as resting in the thumb's frontal plane. Abduction and adduction of the first CMC joint occur in this plane; this remains true regardless of how the first metacarpal bone is being rotated during opposition and reposition. Male and female thumb CMC joints are different in some aspects. In women, the trapezial articular surface is smaller than the metacarpal surface, its shape differs from that of ma
Bats are mammals of the order Chiroptera. Bats are more manoeuvrable than birds, flying with their long spread-out digits covered with a thin membrane or patagium; the smallest bat, arguably the smallest extant mammal, is Kitti's hog-nosed bat, 29–34 mm in length, 15 cm across the wings and 2–2.6 g in mass. The largest bats are the flying foxes and the giant golden-crowned flying fox, Acerodon jubatus, which can weigh 1.6 kg and have a wingspan of 1.7 m. The second largest order of mammals, bats comprise about 20% of all classified mammal species worldwide, with over 1,200 species; these were traditionally divided into two suborders: the fruit-eating megabats, the echolocating microbats. But more recent evidence has supported dividing the order into Yinpterochiroptera and Yangochiroptera, with megabats as members of the former along with several species of microbats. Many bats are insectivores, most of the rest are frugivores. A few species feed on animals other than insects. Most bats are nocturnal, many roost in caves or other refuges.
Bats are present throughout the world, with the exception of cold regions. They are important in their ecosystems for dispersing seeds. Bats provide humans at the cost of some threats. Bat dung has been used as fertiliser. Bats consume insect pests, they are sometimes numerous enough to serve as tourist attractions, are used as food across Asia and the Pacific Rim. They are natural reservoirs such as rabies. In many cultures, bats are popularly associated with darkness, witchcraft and death. An older English name for bats is flittermouse, which matches their name in other Germanic languages, related to the fluttering of wings. Middle English had bakke, most cognate with Old Swedish natbakka, which may have undergone a shift from -k- to -t- influenced by Latin blatta, "moth, nocturnal insect"; the word "bat" was first used in the early 1570s. The name "Chiroptera" derives from Ancient Greek: χείρ – cheir, "hand" and πτερόν – pteron, "wing"; the delicate skeletons of bats do not fossilise well, it is estimated that only 12% of bat genera that lived have been found in the fossil record.
Most of the oldest known bat fossils were very similar to modern microbats, such as Archaeopteropus. The extinct bats Palaeochiropteryx tupaiodon and Hassianycteris kumari are the first fossil mammals whose colouration has been discovered: both were reddish-brown. Bats were grouped in the superorder Archonta, along with the treeshrews and primates. Modern genetic evidence now places bats in the superorder Laurasiatheria, with its sister taxon as Fereuungulata, which includes carnivorans, odd-toed ungulates, even-toed ungulates, cetaceans. One study places Chiroptera as a sister taxon to odd-toed ungulates; the phylogenetic relationships of the different groups of bats have been the subject of much debate. The traditional subdivision into Megachiroptera and Microchiroptera reflected the view that these groups of bats had evolved independently of each other for a long time, from a common ancestor capable of flight; this hypothesis recognised differences between microbats and megabats and acknowledged that flight has only evolved once in mammals.
Most molecular biological evidence supports the view that bats form a monophyletic group. Genetic evidence indicates that megabats originated during the early Eocene, belong within the four major lines of microbats. Two new suborders have been proposed. Yangochiroptera includes the other families of a conclusion supported by a 2005 DNA study. A 2013 phylogenomic study supported the two new proposed suborders. In the 1980s, a hypothesis based on morphological evidence stated the Megachiroptera evolved flight separately from the Microchiroptera; the flying primate hypothesis proposed that, when adaptations to flight are removed, the Megachiroptera are allied to primates by anatomical features not shared with Microchiroptera. For example, the brains of megabats have advanced characteristics. Although recent genetic studies support the monophyly of bats, debate continues about the meaning of the genetic and morphological evidence; the 2003 discovery of an early fossil bat from the 52 million year old Green River Formation, Onychonycteris finneyi, indicates that flight evolved before echolocative abilities.
Onychonycteris had claws on all five of its fingers, whereas modern bats have at most two claws on two digits of each hand. It had longer hind legs and shorter forearms, similar to climbing mammals that hang under branches, such as sloths and gibbons; this palm-sized bat had short, broad wings, suggesting that it could not fly as fast or as far as bat species. Instead of flapping its wings continuously while flying, Onychonycteris alternated between flaps and
In biology, homology is the existence of shared ancestry between a pair of structures, or genes, in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats, the arms of primates, the front flippers of whales and the forelegs of dogs and horses are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor; the term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, it was explicitly analysed by Pierre Belon in 1555. In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching primordia in successive segments of the same animal, are serially homologous.
Examples include the legs of a centipede, the maxillary palp and labial palp of an insect, the spinous processes of successive vertebrae in a vertebral column. Male and female reproductive organs are homologous if they develop from the same embryonic tissue, as do the ovaries and testicles of mammals including humans. Sequence homology between protein or DNA sequences is defined in terms of shared ancestry. Two segments of DNA can have shared ancestry because of either a speciation event or a duplication event. Homology among proteins or DNA is inferred from their sequence similarity. Significant similarity is strong evidence that two sequences are related by divergent evolution from a common ancestor. Alignments of multiple sequences are used to discover the homologous regions. Homology remains controversial in animal behaviour, but there is suggestive evidence that, for example, dominance hierarchies are homologous across the primates. Homology was noticed by Aristotle, was explicitly analysed by Pierre Belon in his 1555 Book of Birds, where he systematically compared the skeletons of birds and humans.
The pattern of similarity was interpreted as part of the static great chain of being through the mediaeval and early modern periods: it was not seen as implying evolutionary change. In the German Naturphilosophie tradition, homology was of special interest as demonstrating unity in nature. In 1790, Goethe stated his foliar theory in his essay "Metamorphosis of Plants", showing that flower part are derived from leaves; the serial homology of limbs was described late in the 18th century. The French zoologist Etienne Geoffroy Saint-Hilaire showed in 1818 in his theorie d'analogue that structures were shared between fishes, reptiles and mammals; when Geoffroy went further and sought homologies between Georges Cuvier's embranchements, such as vertebrates and molluscs, his claims triggered the 1830 Cuvier-Geoffroy debate. Geoffroy stated the principle of connections, namely that what is important is the relative position of different structures and their connections to each other; the Estonian embryologist Karl Ernst von Baer stated what are now called von Baer's laws in 1828, noting that related animals begin their development as similar embryos and diverge: thus, animals in the same family are more related and diverge than animals which are only in the same order and have fewer homologies.
Von Baer's theory recognises that each taxon has distinctive shared features, that embryonic development parallels the taxonomic hierarchy: not the same as recapitulation theory. The term "homology" was first used in biology by the anatomist Richard Owen in 1843 when studying the similarities of vertebrate fins and limbs, defining it as the "same organ in different animals under every variety of form and function", contrasting it with the matching term "analogy" which he used to describe different structures with the same function. Owen codified 3 main criteria for determining if features were homologous: position and composition. In 1859, Charles Darwin explained homologous structures as meaning that the organisms concerned shared a body plan from a common ancestor, that taxa were branches of a single tree of life; the word homology, coined in about 1656, is derived from the Greek ὁμόλογος homologos from ὁμός homos "same" and λόγος logos "relation". Biological structures or sequences in different taxa are homologous if they are derived from a common ancestor.
Homology thus implies divergent evolution. For example, many insects possess two pairs of flying wings. In beetles, the first pair of wings has evolved into a pair of hard wing covers, while in Dipteran flies the second pair of wings has evolved into small halteres used for balance; the forelimbs of ancestral vertebrates have evolved into the front flippers of whales, the wings of birds, the running forelegs of dogs and horses, the short forelegs of frogs and lizards, the grasping hands of primates including humans. The same major forearm bones are found in fossils of lobe-finned fish such as Eusthenopteron; the opposite of homologous organs are analogous organs which do similar jobs in two taxa that were not present in their most recent common ancestor but rather evolved separately. For example, the wings of insects and birds evolved independently in separated groups, converged functionally to support powered flight, so they are analogous; the wings of a sycamore maple seed and the wings of a bird are analogous but not homologous, as they develop from quite different structures.
A structure can be only analogous at another. Pterosaur and bat wings are analogous as wings
Extensor carpi ulnaris muscle
In human anatomy, the extensor carpi ulnaris is a skeletal muscle located on the ulnar side of the forearm. It acts to adduct at the carpus/wrist from anatomical position. Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm, it originates from the lateral epicondyle of the humerus and the posterior border of the ulna, crosses the forearm to the ulnar side to insert at the base of the 5th metacarpal. The extensor carpi ulnaris extends the wrist, but when acting alone inclines the hand toward the ulnar side; the muscle has become a flexor in ungulates. In this case it is described as ulnaris lateralis. Despite its name, the extensor carpi ulnaris is innervated by the posterior interosseous nerve, the continuation of the deep branch of the radial nerve, it would therefore be paralyzed in an injury to the posterior cord of the brachial plexus. A common injury to the extensor carpi ulnaris is tennis elbow; this injury occurs in people that participate in activities requiring repetitive arm and wrist when they are gripping an object.
Some symptoms include pain when squeezing/gripping an object. The pain worsens; the pain intensifies because the extensor carpi ulnaris has an injury near the elbow area and as a person moves their arm, the muscle contracts, thus causing it to move over the medial epicondyle of the humerus. This causes irritation to the existing injury; some treatments for tennis elbow include occupational therapy, physical therapy, anti-inflammatory medication, rest from the activity that caused the injury. A similar injury involving the medial elbow is known as golfers elbow. An ECU injury most requires imaging for diagnosis. After the ECU injury is diagnosed, a physician will choose a course of treatment, which depends upon the severity of the injury. Conservative treatments include immobilization and stabilization of the affected wrist by placing it in a cast. A long arm cast may be required in order to ensure; the duration of the immobilization is at the treating physician's discretion. After the immobilization period has ended, the cast will be removed and further analysis of the injury will be required.
If the injury did not improve with the conservative courses of treatment, or if the injury was too severe for conservative treatment, invasive procedures may become necessary. Steroid injections and surgical procedures are the most prominent invasive procedures. Surgical repair or reconstruction of the ECU is not required, yet a severe ECU injury may cause these approaches to be necessary