Flexor pollicis brevis muscle
The flexor pollicis brevis is a muscle in the hand that flexes the thumb. It is one of three thenar muscles, it has both a deep part. The muscle's superficial head arises from the distal edge of the flexor retinaculum and the tubercle of the trapezium, the most lateral bone in the distal row of carpal bones, it passes along the radial side of the tendon of the flexor pollicis longus. The deeper head "varies in size and may be absent." It arises from the trapezoid and capitate bones on the floor of the carpal tunnel, as well as the ligaments of the distal carpal row. Both heads become tendinous and insert together into the radial side of the base of the proximal phalanx of the thumb; the superficial head is innervated by the lateral terminal branch of the median nerve. The deep part is innervated by the deep branch of the ulnar nerve; the flexor pollicis brevis receives its blood supply from the superficial palmar branches of radial artery. The flexor pollicis brevis flexes the thumb at the metacarpophalangeal joint, as well as flexion and medial rotation of the 1st metacarpal bone at the carpometacarpal joint.
This article incorporates text in the public domain from page 461 of the 20th edition of Gray's Anatomy
Coronoid process of the ulna
The Ulna's coronoid process is a triangular eminence projecting forward from the anterior proximal portion of the ulna. Its base is continuous with the body of the bone, of considerable strength, its apex is pointed curved upward, in flexion of the forearm is received into the coronoid fossa of the humerus. Its upper surface is smooth and forms the lower part of the semilunar notch, its antero-inferior surface is concave, marked by a rough impression for the insertion of the brachialis muscle. At the junction of this surface with the front of the body is a rough eminence, the tuberosity of the ulna, which gives insertion to a part of the brachialis, its lateral surface presents a narrow, articular depression, the radial notch. Its medial surface, by its prominent, free margin, serves for the attachment of part of the ulnar collateral ligament. At the front part of this surface is a small rounded eminence for the origin of one head of the flexor digitorum superficialis muscle; the flexor pollicis longus muscle arises from the lower part of the coronoid process by a rounded bundle of muscular fibers.
The coronoid process of the ulna should not be confused with the similar-sounding coracoid process of the scapula. This article incorporates text in the public domain from page 214 of the 20th edition of Gray's Anatomy lesson4bonesofantforearm at The Anatomy Lesson by Wesley Norman, radiographsul at The Anatomy Lesson by Wesley Norman Right ulna - BioWeb at University of Wisconsin System X-ray at uams.edu
Extensor pollicis longus muscle
In human anatomy, the extensor pollicis longus muscle is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it covers and acts to stretch the thumb together with this muscle; the extensor pollicis longus arises from the dorsal surface of the ulna and from the interosseous membrane, next to the origins of abductor pollicis longus and extensor pollicis brevis. Passing through the third tendon compartment, lying in a narrow, oblique groove on the back of the lower end of the radius, it crosses the wrist close to the dorsal midline before turning towards the thumb using Lister's tubercle on the distal end of the radius as a pulley, it obliquely crosses the tendons of the extensores carpi radialis longus and brevis, is separated from the extensor pollicis brevis by a triangular interval, the anatomical snuff box in which the radial artery is found. At the proximal phalanx, the tendon is joined by expansions from abductor pollicis brevis and adductor pollicis.
The tendon is inserted on the base of the distal phalanx of the thumb.6.7 to 9.7 centimetres in length, the tendon passes through a long and superficial synovial sheath which, passing obliquely from the radial border of the forearm into the thumb, extends from the proximal border of the extensor retinaculum to the first carpometacarpal joint. In the synovial sheath a proximal and a distal mesotendon connect the tendon to the floor of the sheath. Together with the tendons of the extensor pollicis brevis and the abductor pollicis longus, its tendon crosses the radial artery; the tendon of extensor pollicis longus is supplied by branches from various arteries. Before the tendon enters its synovial sheath, arteries from the anterior interosseous artery or its muscular branches enter the tendon; the sheath itself is supplied by the posterior ramus of the same artery. In the metacarpal region, beyond the synovial sheath, the tendon is supplied directly from the radial artery. At the phalanges, the tendon forms a dorsal aponeurosis, supplied by a digital branch of the first dorsal metacarpal artery.
The extensor pollicis longus muscle receives innervation from the posterior interosseous nerve, the continuation of the deep branch of the radial nerve. Extensor pollicis longus extends the terminal phalanx of the thumb. While abductor pollicis brevis and adductor pollicis, both attached to the extensor pollicis longus tendon, can extend the thumb's interphalangeal joint to the neutral position, only extensor pollicis longus can achieve full hyperextension at the interphalangeal joint; this complete extension at the interphalangeal joint is not possible, or more difficult, with the carpal and metacarpophalangeal joints extended. Flexion at the interphalangeal joint by flexor pollicis longus is reduced in wrist flexion, it applies an extensor force at the metacarpophalangeal joint together with the extensor pollicis brevis and extends and adducts at the carpometacarpal joint of the thumb. Tenosynovitis, inflammatory irritation of the synovial sheath, is common in the third compartment after repetitive activities such as drum playing.
This article incorporates text in the public domain from page 455 of the 20th edition of Gray's Anatomy
Anterior interosseous artery
The anterior interosseous artery is an artery in the forearm. It is a branch of the common interosseous artery, it passes down the forearm on the palmar surface of the interosseous membrane. It is accompanied by the palmar interosseous branch of the median nerve, overlapped by the contiguous margins of the flexor digitorum profundus and flexor pollicis longus muscles, giving off in this situation muscular branches, the nutrient arteries of the radius and ulna. At the upper border of the pronator quadratus muscle it pierces the interosseous membrane and reaches the back of the forearm, where it anastomoses with the dorsal interosseous artery, it descends, in company with the terminal portion of the dorsal interosseous nerve, to the back of the wrist to join the dorsal carpal network. The anterior interosseous artery may give off a slender branch, the median artery, which accompanies the median nerve, gives offsets to its substance. Before it pierces the interosseous membrane the anterior interosseous sends a branch downward behind the pronator quadratus muscle to join the palmar carpal network.
The anterior interosseous artery supplies the deep layer of the anterior compartment of the forearm, including the flexor digitorum profundus, flexor pollicis longus, pronator quadratus muscles. Posterior interosseous artery Ulnar artery This article incorporates text in the public domain from page 596 of the 20th edition of Gray's Anatomy lesson4artofforearm at The Anatomy Lesson by Wesley Norman Atlas image: hand_blood3 at the University of Michigan Health System - "Dorsum of the hand, deep dissection, posterior view"
Anatomical terms of motion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints and specific sections of the body; the terminology used describes this motion according to its direction relative to the anatomical position of the joints. Anatomists use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing the uniqueness of the movements such as those of the hands and eyes. In general, motion is classified according to the anatomical plane. Flexion and extension are examples of angular motions, in which two axes of a joint are brought closer together or moved further apart. Rotational motion may occur at other joints, for example the shoulder, are described as internal or external. Other terms, such as elevation and depression, describe movement above or below the horizontal plane. Many anatomical terms derive from Latin terms with the same meaning. Motions are classified after the anatomical planes they occur in, although movement is more than not a combination of different motions occurring in several planes.
Motions can be split into categories relating to the nature of the joints involved: Gliding motions occur between flat surfaces, such as in the intervertebral discs or between the carpal and metacarpal bones of the hand. Angular motions occur over synovial joints and causes them to either increase or decrease angles between bones. Rotational motions move a structure in a rotational motion along a longitudinal axis, such as turning the head to look to either side. Apart from this motions can be divided into: Linear motions, which move in a line between two points. Rectilinear motion is motion in a straight line between two points, whereas curvilinear motion is motion following a curved path. Angular motions occur when an object is around another object decreasing the angle; the different parts of the object do not move the same distance. Examples include a movement of the knee, where the lower leg changes angle compared to the femur, or movements of the ankle; the study of movement is known as kinesiology.
A categoric list of movements of the human body and the muscles involved can be found at list of movements of the human body. The prefix hyper- is sometimes added to describe movement beyond the normal limits, such as in hypermobility, hyperflexion or hyperextension; the range of motion describes the total range of motion. For example, if a part of the body such as a joint is overstretched or "bent backwards" because of exaggerated extension motion it can be described as hyperextended. Hyperextension increases the stress on the ligaments of a joint, is not always because of a voluntary movement, it may be other causes of trauma. It may be used in surgery, such as in temporarily dislocating joints for surgical procedures; these are general terms. Most terms have a clear opposite, so are treated in pairs. Flexion and extension describe movements; these terms come from the Latin words with the same meaning. Flexion describes a bending movement that decreases the angle between a segment and its proximal segment.
For example, bending the elbow, or clenching a hand into a fist, are examples of flexion. When sitting down, the knees are flexed; when a joint can move forward and backward, such as the neck and trunk, flexion refers to movement in the anterior direction. When the chin is against the chest, the head is flexed, the trunk is flexed when a person leans forward. Flexion of the shoulder or hip refers to movement of the leg forward. Extension is the opposite of flexion, describing a straightening movement that increases the angle between body parts. For example, when standing up, the knees are extended; when a joint can move forward and backward, such as the neck and trunk, extension refers to movement in the posterior direction. Extension of the hip or shoulder moves the leg backward. Abduction is the motion of a structure away from the midline while adduction refer to motion towards the center of the body; the centre of the body is defined as the midsagittal plane. These terms come from Latin words with similar meanings, ab- being the Latin prefix indicating "away," ad- indicating "toward," and ducere meaning "to draw or pull".
Abduction refers to a motion that pulls a part away from the midline of the body. In the case of fingers and toes, it refers to spreading the digits apart, away from the centerline of the hand or foot. Abduction of the wrist is called radial deviation. For example, raising the arms up, such as when tightrope-walking, is an example of abduction at the shoulder; when the legs are splayed at the hip, such as when doing a star jump or doing a split, the legs are abducted at the hip. Adduction refers to a motion that pulls a structure or part toward the midline of the body, or towards the midline of a limb. In the case of fingers and toes, it refers to bringing the digits together, towards the centerline of the hand or foot. Adduction of the wrist is called ulnar deviation. Dropping the arms to the sides, bringing the knees together, are examples of adduction. Ulnar deviation is the hand moving towards the ulnar styloid. Radial deviation is the hand moving towards the radial styloid; the terms elevation and depression refer to movement below the horizontal.
They derive from the Latin terms with similar meaningsElevation refers to movement in a superior direction. For example
Gibbons are apes in the family Hylobatidae. The family contained one genus, but now is split into four genera and 18 species. Gibbons live in tropical and subtropical rainforests from eastern Bangladesh and northeast India to southern China and Indonesia. Called the smaller apes or lesser apes. Gibbons differ from great apes in being smaller, exhibiting low sexual dimorphism, not making nests. In certain anatomical details, they superficially more resemble monkeys than great apes do, but like all apes, gibbons are tailless. Unlike most of the great apes, gibbons form long-term pair bonds, their primary mode of locomotion, involves swinging from branch to branch for distances up to 15 m, at speeds as high as 55 km/h. They can make leaps up to 8 m, walk bipedally with their arms raised for balance, they are the most agile of all tree-dwelling, nonflying mammals. Depending on species and sex, gibbons' fur coloration varies from dark to light brown shades, any shade between black and white, though a "white" gibbon is rare.
Gibbon species include the siamang, the white-handed or lar gibbon, the hoolock gibbons. Whole genome molecular dating analyses indicate that the gibbon lineage diverged from that of great apes around 16.8 million years ago. Adaptive divergence associated with chromosomal rearrangements led to rapid radiation of the four genera 5-7 Mya; each genus comprises a distinct, well-delineated lineage, but the sequence and timing of divergences among these genera has been hard to resolve with whole genome data, due to radiative speciations and extensive incomplete lineage sorting. An analysis based on morphology suggests that the four genera are ordered as A coalescent-based species tree analysis of genome-scale datasets suggests a phylogeny for the four genera ordered as. At the species level, estimates from mitochondrial DNA genome analyses suggest that Hylobates pileatus diverged from H. lar and H. agilis around 3.9 Mya, H. lar and H. agilis separated around 3.3 Mya. Whole genome analysis suggests divergence of Hylobates pileatus from Hylobates moloch 1.5-3.0 Mya.
The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until was thought to be related to the hoolock gibbons. Family Hylobatidae: gibbons The family is divided into four genera based on their diploid chromosome number: Hylobates, Hoolock and Symphalangus. There is an extinct fifth genus named Bunopithecus, either a gibbon or gibbon-like ape. An extinct sixth genus, was identified in 2018 based on a partial skull found in China. Genus Hoolock Western hoolock gibbon, H. hoolock Eastern hoolock gibbon, H. leuconedys Skywalker hoolock gibbon, H. tianxing Genus Hylobates: dwarf gibbons Lar gibbon or white-handed gibbon, H. lar Malaysian lar gibbon, H. l. lar Carpenter's lar gibbon, H. l. carpenteri Central lar gibbon, H. l. entelloides Sumatran lar gibbon, H. l. vestitus Yunnan lar gibbon, H. l. yunnanensis Bornean white-bearded gibbon, H. albibarbis Agile gibbon or black-handed gibbon, H. agilis Müeller's gibbon, H. muelleri Müeller's grey gibbon, H. m. muelleri Abbott's grey gibbon, H. m. abbotti Northern grey gibbon, H. m. funereus Silvery gibbon, H. moloch Western silvery gibbon or western Javan gibbon, H. m. moloch Eastern silvery gibbon or central Javan gibbon, H. m. pongoalsoni Pileated gibbon or capped gibbon, H. pileatus Kloss's gibbon, Mentawai gibbon or bilou, H. klossii Genus Symphalangus Siamang, S. syndactylus Genus Nomascus: crested gibbons Northern buffed-cheeked gibbon, N. annamensis Concolor or black crested gibbon, N. concolor Tonkin black crested gibbon, N. c. concolor Laotian black crested gibbon, N. c. lu Central Yunnan black crested gibbon, N. c. jingdongensis West Yunnan black crested gibbon, N. c. furvogaster Eastern black crested gibbon or Cao Vit black crested gibbon, N. nasutus Hainan black crested gibbon, N. hainanus Northern white-cheeked gibbon, N. leucogenys Southern white-cheeked gibbon, N. siki Yellow-cheeked gibbon, N. gabriellae Genus Bunopithecus Bunopithecus sericus Genus Junzi Junzi imperialis Many gibbons are hard to identify based on fur coloration, so are identified either by song or genetics.
These morphological ambiguities have led to hybrids in zoos. Zoos receive gibbons of unknown origin, so they rely on morphological variation or labels that are impossible to verify to assign species and subspecies names, so separate species of gibbons are misidentified and housed together. Interspecific hybrids, hybrids within a genus, are suspected to occur in wild gibbons where their ranges overlap. However, no records exist of fertile hybrids between different gibbon genera, either in the wild or in captivity. One unique aspect of a gibbon's anatomy is the wrist, which functions something like a ball and socket joint, allowing for biaxial movement; this reduces the amount of energy needed in the upper arm and torso, while reducing stress on the shoulder joint. Gibbons have long hands and feet, with a deep cleft between the first and second digits of their hands, their fur is black, gray, or brownish with white markings on hands and face. Some species have an enlarged throat sac, which inflates and serves as a resonating chamber when the animals call.
This structure can become quite large in some species, sometimes equaling the size of the animal's head. Their voices are much more powerful than that of any human singer, although they
A tendon or sinew is a tough band of fibrous connective tissue that connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments. Ligaments join one bone to bone, while tendons connect muscle to bone for a proper functioning of the body. Histologically, tendons consist of dense regular connective tissue fascicles encased in dense irregular connective tissue sheaths. Normal healthy tendons are composed of parallel arrays of collagen fibers packed together, they are anchored to bone by Sharpey's fibres. The dry mass of normal tendons, which makes up about 30% of their total mass, is composed of about 86% collagen, 2% elastin, 1–5% proteoglycans, 0.2% inorganic components such as copper and calcium. The collagen portion is made up of 97–98% type I collagen, with small amounts of other types of collagen; these include type II collagen in the cartilaginous zones, type III collagen in the reticulin fibres of the vascular walls, type IX collagen, type IV collagen in the basement membranes of the capillaries, type V collagen in the vascular walls, type X collagen in the mineralized fibrocartilage near the interface with the bone.
Collagen fibres coalesce into macroaggregates. After secretion from the cell, the cleaved by procollagen N- and C-proteinases, the tropocollagen molecules spontaneously assemble into insoluble fibrils. A collagen molecule is about 300 nm long and 1–2 nm wide, the diameter of the fibrils that are formed can range from 50–500 nm. In tendons, the fibrils assemble further to form fascicles, which are about 10 mm in length with a diameter of 50–300 μm, into a tendon fibre with a diameter of 100–500 μm. Fascicles are bound by the endotendineum, a delicate loose connective tissue containing thin collagen fibrils. and elastic fibres. Groups of fascicles are bounded by the epitenon. Filling the interstitia within the fascia where the tendon is located is the paratenon a fatty areolar tissue; the collagen in tendons are held together with proteoglycan components including decorin and, in compressed regions of tendon, which are capable of binding to the collagen fibrils at specific locations. The proteoglycans are interwoven with the collagen fibrils – their glycosaminoglycan side chains have multiple interactions with the surface of the fibrils – showing that the proteoglycans are important structurally in the interconnection of the fibrils.
The major GAG components of the tendon are dermatan sulfate and chondroitin sulfate, which associate with collagen and are involved in the fibril assembly process during tendon development. Dermatan sulfate is thought to be responsible for forming associations between fibrils, while chondroitin sulfate is thought to be more involved with occupying volume between the fibrils to keep them separated and help withstand deformation; the dermatan sulfate side chains of decorin aggregate in solution, this behavior can assist with the assembly of the collagen fibrils. When decorin molecules are bound to a collagen fibril, their dermatan sulfate chains may extend and associate with other dermatan sulfate chains on decorin, bound to separate fibrils, therefore creating interfibrillar bridges and causing parallel alignment of the fibrils; the tenocytes produce the collagen molecules, which aggregate end-to-end and side-to-side to produce collagen fibrils. Fibril bundles are organized to form fibres with the elongated tenocytes packed between them.
There is a three-dimensional network of cell processes associated with collagen in the tendon. The cells communicate with each other through gap junctions, this signalling gives them the ability to detect and respond to mechanical loading. Blood vessels may be visualized within the endotendon running parallel to collagen fibres, with occasional branching transverse anastomoses; the internal tendon bulk is thought to contain no nerve fibres, but the epitenon and paratenon contain nerve endings, while Golgi tendon organs are present at the junction between tendon and muscle. Tendon length varies from person to person. Tendon length is, in practice, the deciding factor regarding potential muscle size. For example, all other relevant biological factors being equal, a man with a shorter tendons and a longer biceps muscle will have greater potential for muscle mass than a man with a longer tendon and a shorter muscle. Successful bodybuilders will have shorter tendons. Conversely, in sports requiring athletes to excel in actions such as running or jumping, it is beneficial to have longer than average Achilles tendon and a shorter calf muscle.
Tendon length is determined by genetic predisposition, has not been shown to either increase or decrease in response to environment, unlike muscles, which can be shortened by trauma, use imbalances and a lack of recovery and stretching. Traditionally, tendons have been considered to be a mechanism by which muscles connect to bone as well as muscles itself, functioning to transmit forces; this connection allows tendons to passively modulate forces during locomotion, providing additional stability with no active work. However, over the past two decades, much research focused on the elastic properties of some tendons and their ability to function as springs. Not all tendons are required to perform the same functional role, with some predominantly positioning limbs, such as the fingers when writing and others acting as springs to make locomotion more efficient. Energy storing tendons can recover energy at high efficiency. For example, during a human stride, the Achilles tendon stretches as the ankle joint dorsiflexes.
During the last portion of the stride, as the foot plantar-flexes (pointing the