The metaphysis (: metaphyses) is the neck portion of a

long bone 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 ...

between the epiphysis and the

diaphysis The diaphysis (: diaphyses) is the main or midsection (shaft) of a long bone. It is made up of cortical bone and usually contains bone marrow and adipose tissue (fat). It is a middle tubular part composed of compact bone which surrounds a centr ...

. It contains the growth plate, the part of the bone that grows during childhood, and as it grows it

ossifies Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by Cell (biology), cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes r ...

near the diaphysis and the epiphyses. The metaphysis contains a diverse population of cells including mesenchymal stem cells, which give rise to

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 fat cells, as well as hematopoietic stem cells which give rise to a variety of blood cells as well as bone-destroying cells called

osteoclasts An osteoclast () is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated ...

. Thus the metaphysis contains a highly metabolic set of tissues including trabecular (spongy) bone, blood vessels, as well as marrow adipose tissue (MAT). The metaphysis may be divided anatomically into three components based on tissue content: a cartilaginous component (

epiphyseal plate 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 ma ...

), a bony component (metaphysis) and a fibrous component surrounding the periphery of the plate. The growth plate synchronizes chondrogenesis with osteogenesis or interstitial cartilage growth with both appositional bone elongation in conjunction with growth in width, so bearing load and responding to local and systemic forces and factors balance one another mechanically. During childhood, the growth plate contains the connecting cartilage enabling the bone to grow; at adulthood (between the ages of 18 and 25 years), the components of the growth plate stop growing altogether and completely ossify into solid bone. In an adult, the metaphysis functions to transfer loads from weight-bearing joint surfaces to the diaphysis."metaphysis"
''Encyclopædia Britannica''.

Clinical significance

Because of their rich blood supply and vascular stasis, metaphyses of long bones are prone to hematogenous spread of

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

in children. Metaphyseal tumors or lesions include

osteosarcoma An osteosarcoma (OS) or osteogenic sarcoma (OGS) is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchyme, mesenchymal origin (and thus a sarcoma) and that exhi ...

chondrosarcoma Chondrosarcoma is a bone sarcoma, a primary cancer composed of cells derived from transformed cells that produce cartilage. A chondrosarcoma is a member of a category of tumors of bone and soft tissue known as sarcomas. About 30% of bone sarco ...

fibrosarcoma Fibrosarcoma (fibroblastic sarcoma) is a malignant mesenchymal tumour derived from fibrous connective tissue and characterized by the presence of immature proliferating fibroblasts or undifferentiated anaplastic spindle cells in a storiform ...

osteoblastoma Osteoblastoma is an uncommon osteoid tissue-forming primary neoplasm of the bone. It has clinical and histologic manifestations similar to those of osteoid osteoma; therefore, some consider the two tumors to be variants of the same disease, wi ...

enchondroma Enchondroma is a type of benign bone tumor belonging to the group of cartilage tumors. There may be no symptoms, or it may present typically in the short tubular bones of the hands with a swelling, pain or pathological fracture. Diagnosis i ...

fibrous dysplasia Fibrous dysplasia is a very rare nonhereditary genetic disorder where normal bone and marrow is replaced with fibrous tissue, resulting in formation of bone that is weak and prone to expansion. As a result, most complications result from fract ...

simple bone cyst A unicameral bone cyst, also known as a simple bone cyst, is a cavity filled with a yellow-colored fluid. It is considered to be benign since it does not spread beyond the bone. Unicameral bone cysts can be classified into two categories: active ...

aneurysmal bone cyst Aneurysmal bone cyst (ABC) is a non-cancerous bone tumor composed of multiple varying sizes of spaces in a bone which are filled with blood. The term is a misnomer, as the lesion is neither an aneurysm nor a cyst. It generally presents with ...

non-ossifying fibroma A non-ossifying fibroma (NOF) is a benign bone tumor of the osteoclastic, Giant-cell tumor of bone, giant cell-rich tumor type. It generally occurs in the metaphysis of long bones in children and adolescents. Typically, there are no symptoms unl ...

, and osteoid osteoma. One of the clinical signs of rickets that doctors look for is cupping and fraying at the metaphyses when seen on

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

References

External links

* - "Bone, structure (Gross, Low)" {{Authority control Skeletal system Long bones

Clinical significance

See also

References

External links