Short bone | |
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Details | |
Identifiers | |
Latin | os breve |
TA98 | A02.0.00.012 |
TA2 | 370 |
FMA | 7475 |
Anatomical terms of bone |
Short bones are designated as those bones that are more or less equal in length, width, and thickness. They include the tarsals in the ankle and the carpals in the wrist. They are one of five types of bones: short, long, flat, irregular and sesamoid. Most short bones are named according to their shape as they exhibit a variety of complex morphological features (They can be cuboid, lenticular, trapezoidal, etc.) [1] [2]
Some authors state that short bones are only located in the carpals and tarsals. [3] The metacarpals, metatarsals and phalanges are considered long bones as they have a shaft (tubular diaphysis), but since they're smaller than typical long bones, they're called “miniature, small or short" long bones. [1] [4] Nevertheless, others consider the patellae and other sesamoid bones, the vertebral bodies, the bones of the skull base and even the phalanges to be short bones. [2] [5]
The carpus and tarsus consist of cancellous tissue covered by a thin crust of compact substance. [5] Short bones are specialized to provide support in areas of the skeleton that are subjected to high forces or need to be very compact and where strength and stability are more important than range of motion. [1] Short bones are characterized by their multiple articular surfaces and their tendency to form movable joints with adjacent bones. The articular surfaces of short bones are covered with hyaline cartilage, similar to long bones. The outer surface of the bone, except for the articular surfaces, is covered by the periosteum. [6] Short bones have no clear diaphysis (bone shaft) and metaphysis and have poor vascular supply. [1] [2]
Both short and long bones undergo endochondral ossification during development. In this process, bone is formed from an initial cartilaginous model and this model is then gradually replaced by bone. Despite sharing a common cellular origin, short and long bones have different structural features. [7]
Long bones have epiphyseal growth plates, where chondrocytes, stacked on top of each other, form longitudinal columns that are responsible for longitudinal growth of the bone. Long bones also have secondary ossification centers, in which cell columns are arranged in a radial pattern from the center like spokes on a wheel and cartilage-to-bone replacement starts in the center and extends centrifugally outwards. [2] [8]
Contrary to long bones, the carpals and tarsals typically lack epiphyseal growth plates, hence lacking longitudinal growth and they undergo ossification radially, similar to secondary ossification centers in long bones. [9] [10] [11] As a result, short bones usually develop from a single ossification nucleus, while long bones usually develop from multiple ossification nuclei. [12]
Short bones are more prone to nonunion, malunion or osteonecrosis in case of fractures due to their tenuous vascular supply leading to lower healing potential. In contrast, the mid-diaphysis of the femur has a robust vascular supply from the surrounding muscle, and typically heals relatively quickly and reliably. [1] [13] This risk of diminished healing of short bone fractures increases in diabetic patients, probably due to diabetic peripheral neuropathy and microvascular dysfunction. [14]
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.
Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and the bronchial tubes, and the intervertebral discs. In other taxa, such as chondrichthyans and cyclostomes, it constitutes a much greater proportion of the skeleton. It is not as hard and rigid as bone, but it is much stiffer and much less flexible than muscle. The matrix of cartilage is made up of glycosaminoglycans, proteoglycans, collagen fibers and, sometimes, elastin. It usually grows quicker than bone.
The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.
In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; (2) the wrist joint or radiocarpal joint, the joint between the radius and the carpus and; (3) the anatomical region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of the metacarpus or five metacarpal bones and the series of joints between these bones, thus referred to as wrist joints. This region also includes the carpal tunnel, the anatomical snuff box, bracelet lines, the flexor retinaculum, and the extensor retinaculum.
The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur 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.
The metatarsal bones or metatarsus are a group of five long bones in the midfoot, located between the tarsal bones and the phalanges (toes). Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth metatarsal. The metatarsals are analogous to the metacarpal bones of the hand. The lengths of the metatarsal bones in humans are, in descending order, second, third, fourth, fifth, and first. A bovine hind leg has two metatarsals.
An epiphysis is one of the rounded ends or tips of a long bone that ossify from one or more secondary centers of ossification. Between the epiphysis and diaphysis lies the metaphysis, including the epiphyseal plate. During formation of the secondary ossification center, vascular canals stemming from the perichondrium invade the epiphysis, supplying nutrients to the developing secondary centers of ossification. At the joint, the epiphysis is covered with articular cartilage; below that covering is a zone similar to the epiphyseal plate, known as subchondral bone. The epiphysis is mostly found in mammals but it is also present in some lizards. However, the secondary center of ossification may have evolved multiple times, having been found in the Jurassic sphenodont Sapheosaurus as well as in the therapsid Niassodon mfumukasi.
The navicular bone is a small bone found in the feet of most mammals.
The pisiform bone, also spelled pisiforme, is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel.
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones.
The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility. They grow primarily by elongation of the diaphysis, with an epiphysis at each end of the growing bone. The ends of epiphyses are covered with hyaline cartilage. The longitudinal growth of long bones is a result of endochondral ossification at the epiphyseal plate. Bone growth in length is stimulated by the production of growth hormone (GH), a secretion of the anterior lobe of the pituitary gland.
Endochondral ossification is one of the two essential pathways by which bone tissue is produced during fetal development of the mammalian skeletal system, the other pathway being intramembranous ossification. Both endochondral and intramembranous processes initiate from a precursor mesenchymal tissue, but their transformations into bone are different. In intramembranous ossification, mesenchymal tissue is directly converted into bone. On the other hand, endochondral ossification starts with mesenchymal tissue turning into an intermediate cartilage stage, which is eventually substituted by bone.
Ossification in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in the formation of normal, healthy bone tissue: Intramembranous ossification is the direct laying down of bone into the primitive connective tissue (mesenchyme), while endochondral ossification involves cartilage as a precursor.
The epiphyseal plate, epiphysial plate, physis, or growth plate is a hyaline cartilage plate in the metaphysis at each end of a long bone. It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, with maintenance remodeling throughout its existing bone tissue, but the growth plate is the place where the long bone grows longer.
An ossification center is a point where ossification of the hyaline cartilage begins. The first step in ossification is that the chondrocytes at this point become hypertrophic and arrange themselves in rows.
A Salter–Harris fracture is a fracture that involves the epiphyseal plate of a bone, specifically the zone of provisional calcification. It is thus a form of child bone fracture. It is a common injury found in children, occurring in 15% of childhood long bone fractures. This type of fracture and its classification system is named for Robert B. Salter and William H. Harris who created and published this classification system in the Journal of Bone and Joint Surgery in 1963.
Chondroblastoma is a rare, benign, locally aggressive bone tumor that typically affects the epiphyses or apophyses of long bones. It is thought to arise from an outgrowth of immature cartilage cells (chondroblasts) from secondary ossification centers, originating from the epiphyseal plate or some remnant of it.
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 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.
An accessory bone or supernumerary bone is a bone that is not normally present in the body, but can be found as a variant in a significant number of people. It poses a risk of being misdiagnosed as bone fractures on radiography.
Opsismodysplasia is a type of skeletal dysplasia first described by Zonana and associates in 1977, and designated under its current name by Maroteaux (1984). Derived from the Greek opsismos ("late"), the name "opsismodysplasia" describes a delay in bone maturation. In addition to this delay, the disorder is characterized by micromelia, particularly of the hands and feet, delay of ossification, platyspondyly, irregular metaphyses, an array of facial aberrations and respiratory distress related to chronic infection. Opsismodysplasia is congenital, being apparent at birth. It has a variable mortality, with some affected individuals living to adulthood. The disorder is rare, with an incidence of less than 1 per 1,000,000 worldwide. It is inherited in an autosomal recessive pattern, which means the defective (mutated) gene that causes the disorder is located on an autosome, and the disorder occurs when two copies of this defective gene are inherited. No specific gene has been found to be associated with the disorder. It is similar to spondylometaphyseal dysplasia, Sedaghatian type.