|
Sesamoid
In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. Its name is derived from the Arabic word for 'sesame seed', indicating the small size of most sesamoids. Often, these bones form in response to strain, or can be present as a normal variant. The patella is the largest sesamoid bone in the body. Sesamoids act like pulleys, providing a smooth surface for tendons to slide over, increasing the tendon's ability to transmit muscular forces. Structure Sesamoid bones can be found on joints throughout the body, including: * In the knee—the patella (within the quadriceps tendon). This is the largest sesamoid bone. * In the hand—two sesamoid bones are commonly found in the distal portions of the first metacarpal bone (within the tendons of adductor pollicis and flexor pollicis brevis). There is also commonly a sesamoid bone in distal portions of the second metacarpal bone. * In the wrist—The pisiform of the wrist is a sesamoid bone (within the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility. Bones come in a variety of shapes and sizes and have complex internal and external structures. They are lightweight yet strong and hard and serve multiple functions. Bone tissue (osseous tissue), which is also called bone in the uncountable sense of that word, is hard tissue, a type of specialized connective tissue. It has a honeycomb-like matrix internally, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells. Osteoblasts and osteocytes are involved in the formation and mineralization of bone; osteoclasts are involved in the resorption of bone tissue. Modified (flattened) osteoblasts become the lining cells that form a protective layer on the bone surface. The mineralize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hand
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "hand" and fingerprints extremely similar to human fingerprints) are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking. Some evolutionary anatomists use the term ''hand'' to refer to the appendage of digits on the forelimb more generally—for example, in the context of whether the three digits of the bird hand involved the same homologous loss of two digits as in the dinosaur hand. The human hand usually has five digits: four fingers plus one thumb; these are often referred to collectively as five fingers, however, whereby the thumb is included as one of the fingers. It has 27 bones, not including the sesamoid bone, the number ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pisiform
The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisifomis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. Structure The pisiform is a sesamoid bone, with no covering membrane of periosteum. It is the last carpal bone to ossify. The pisiform bone is a small bone found in the proximal row of the wrist ( carpus). It is situated where the ulna joins the wrist, within the tendon of the flexor carpi ulnaris muscle. It only has one side that acts as a joint, articulating with the triquetral bone. It is on a plane anterior to the other carpal bones and is spheroidal in form. The pisiform bone has four surfaces: # The ''dorsal surface'' is smooth and oval, and articulates with the triquetral: this facet approaches the superior, but not the inferior border of the bone. # The ''palmar surface'' is rounded and rough, and gives attachment to the transverse carpal ligament, the flexor carpi ulnari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fabella
The fabella is a small sesamoid bone found in some mammals embedded in the tendon of the lateral head of the gastrocnemius muscle behind the lateral condyle of the femur. It is an accessory bone, an anatomical variation present in 39% of humans. Rarely, there are two or three of these bones (fabella bi- or tripartita). It can be mistaken for a loose body or osteophyte. The word ''fabella'' is a Latin diminutive of ''faba'' 'bean'. In humans, it is more common in men than women, older individuals compared to younger, and there is high regional variation, with fabellae being most common in people living in Asia and Oceania and least common in people living in North America and Africa. Bilateral cases (one per knee) are more common than unilateral ones (one per individual), and within individual cases, fabellae are equally likely to be present in right or left knees. Taken together, these data suggest the ability to form a fabella may be genetically controlled, but fabella ossific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adductor Pollicis
In human anatomy, the adductor pollicis muscle is a muscle in the hand that functions to adduct the thumb. It has two heads: transverse and oblique. It is a fleshy, flat, triangular, and fan-shaped muscle deep in the thenar compartment beneath the long flexor tendons and the lumbrical muscles at the center of the palm. It overlies the metacarpal bones and the interosseous muscles. Structure Oblique head The oblique head (Latin: ''adductor obliquus pollicis'') arises by several slips from the capitate bone, the bases of the second and third metacarpals, the intercarpal ligaments, and the sheath of the tendon of the flexor carpi radialis. Gray's Anatomy 1918. (See infobox) From this origin the greater number of fibers pass obliquely downward and converge to a tendon, which, uniting with the tendons of the medial portion of the flexor pollicis brevis and the transverse head of the adductor pollicis, is inserted into the ulnar side of the base of the proximal phalanx of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot
The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws or nails. Etymology The word "foot", in the sense of meaning the "terminal part of the leg of a vertebrate animal" comes from "Old English fot "foot," from Proto-Germanic *fot (source also of Old Frisian fot, Old Saxon fot, Old Norse fotr, Danish fod, Swedish fot, Dutch voet, Old High German fuoz, German Fuß, Gothic fotus "foot"), from PIE root *ped- "foot". The "plural form feet is an instance of i-mutation." Structure The human foot is a strong and complex mechanical structure containing 26 bones, 33 joints (20 of which are actively articulated), and more than a hundred muscles, tendons, and ligaments.Podiatry Channel, ''Anatomy of the foot and ankle'' The joints of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carpal Bones
The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the wrist is to facilitate effective positioning of the hand and powerful use of the extensors and flexors of the forearm, and the mobility of individual carpal bones increase the freedom of movements at the wrist.Kingston 2000, pp 126-127 In tetrapods, the carpus is the sole cluster of bones in the wrist between the radius and ulna and the metacarpus. The bones of the carpus do not belong to individual fingers (or toes in quadrupeds), whereas those of the metacarpus do. The corresponding part of the foot is the tarsus. The carpal bones allow the wrist to move and rotate vertically. Structure Bones The eight carpal bones may be conceptually organized as either two transverse rows, or three longitudinal columns. Wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patella
The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as mice, cats, birds and dogs, but not in whales, or most reptiles. In humans, the patella is the largest sesamoid bone (i.e., embedded within a tendon or a muscle) in the body. Babies are born with a patella of soft cartilage which begins to ossify into bone at about four years of age. Structure The patella is a sesamoid bone roughly triangular in shape, with the apex of the patella facing downwards. The apex is the most inferior (lowest) part of the patella. It is pointed in shape, and gives attachment to the patellar ligament. The front and back surfaces are joined by a thin margin and towards centre by a thicker margin. The tendon of the quadriceps femoris muscle attaches to the base of the patella., with the vastus intermedius muscl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexor Pollicis Brevis
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 superficial part and a deep part. Origin and insertion 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 (and medial) 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; at the junction between the tendinous heads there is a sesamoid bone.'' Gray's Anatomy'' 1918, see infobox Innervation The superficial head is usually innervated by the lateral terminal branch of the median nerve. The deep part is often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
First Metacarpal Bone
The first metacarpal bone or the metacarpal bone of the thumb is the first bone proximal to the thumb. It is connected to the trapezium of the carpus at the first carpometacarpal joint and to the proximal thumb phalanx at the first metacarpophalangeal joint. Characteristics The first metacarpal bone is short and thick with a shaft thicker and broader than those of the other metacarpal bones. Its narrow shaft connects its widened base and rounded head; the former consisting of a thick cortical bone surrounding the open medullary canal; the latter two consisting of cancellous bone surrounded by a thin cortical shell. Head The head is less rounded and less spherical than those of the other metacarpals, making it better suited for a hinge-like articulation. The distal articular surface is quadrilateral, wide, and flat; thicker and broader transversely and extends much further palmarly than dorsally. On the palmar aspect of the articular surface there is a pair of eminences ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
First Metatarsal Bone
The first metatarsal bone is the bone in the foot just behind the big toe. The first metatarsal bone is the shortest of the metatarsal bones and by far the thickest and strongest of them. Like the four other metatarsals, it can be divided into three parts: base, body and head. The base is the part closest to the ankle and the head is closest to the big toe. The narrowed part in the middle is referred to as the body of the bone. The bone is somewhat flattened, giving it two sides: the plantar (towards the sole of the foot) and the dorsal side (the area facing upwards while standing). The base presents, as a rule, no articular facets (joint surfaces) on its sides, but occasionally on the lateral side there is an oval facet, by which it articulates with the second metatarsal. On the lateral part of the plantar surface there is a rough oval prominence, or tuberosity, for the insertion of the tendon of the fibularis longus. The first metatarsal articulates (forms joints) with the med ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
