The metaphysis 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 The epiphysis () is the rounded end of a long bone, at its joint with adjacent bone(s). Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate). At the jo ...

and the

diaphysis The diaphysis 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 central marrow cavit ...

. 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 cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in th ...

near the diaphysis and the epiphyses. The metaphysis contains a diverse population of cells including

mesenchymal stem cells Mesenchymal stem cells (MSCs) also known as mesenchymal stromal cells or medicinal signaling cells are multipotent stromal cells that can differentiate into a variety of cell types, including osteoblasts (bone cells), chondrocytes (cartilage c ...

, 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 Hematopoietic stem cells (HSCs) are the stem cells that give rise to other blood cells. This process is called haematopoiesis. In vertebrates, the very first definitive HSCs arise from the ventral endothelial wall of the embryonic aorta within ...

which give rise to a variety of blood cells as well as bone-destroying cells called osteoclasts. Thus the metaphysis contains a highly metabolic set of tissues including trabecular (spongy) bone,

blood vessels The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...

, as well as Marrow Adipose Tissue (MAT). The metaphysis may be divided anatomically into three components based on tissue content: a

cartilaginous Cartilage is a resilient and smooth type of connective tissue. 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 a ...

component (

epiphyseal plate The epiphyseal plate (or 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, wit ...

), a bony component (metaphysis) and a

fibrous Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporat ...

component surrounding the periphery of the plate. The growth plate synchronizes

chondrogenesis Chondrogenesis is the process by which cartilage is developed. Cartilage in fetal development In embryogenesis, the skeletal system is derived from the mesoderm germ layer. Chondrification (also known as chondrogenesis) is the process by which ...

with

osteogenesis Osteoblasts (from the Greek combining forms for "bone", ὀστέο-, ''osteo-'' and βλαστάνω, ''blastanō'' "germinate") are cells with a single nucleus that synthesize bone. However, in the process of bone formation, osteoblasts funct ...

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 to 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.Encyclopædia Britannica, http://www.britannica.com/EBchecked/topic/377978/metaphysis

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 an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children e.g. the femur and humerus, while the ...

in children. Metaphyseal tumors or lesions include

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

, chondrosarcoma,

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 pat ...

, osteoblastoma,

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 is by ...

, fibrous dysplasia, simple bone cyst,

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 pai ...

, non-ossifying fibroma, and

osteoid osteoma An osteoid osteoma is a benign (non-cancerous) bone tumor that arises from osteoblasts and some components of osteoclasts. It was originally thought to be a smaller version of an osteoblastoma. Osteoid osteomas tend to be less than 1.5 cm ...

. One of the clinical signs of

rickets Rickets is a condition that results in weak or soft bones in children, and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications ma ...

that doctors look for is cupping and fraying at the metaphyses when seen on

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

References

External links

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

Clinical significance

See also

References

External links