epiphyseal closure

(noun)

The fusion of the epiphysis to the diaphysis.

Related Terms

Examples of epiphyseal closure in the following topics:

  • Postnatal Bone Growth

    • Secondary ossification occurs after birth at the epiphyses of long bones and continues until skeletal maturity.
    • It forms the epiphyses of long bones and the extremities of irregular and flat bones.
    • The diaphysis and both epiphyses of a long bone are separated by a growing zone of cartilage (the epiphyseal plate).
    • When a child reaches skeletal maturity (18 to 25 years of age), all of the cartilage is replaced by bone, fusing the diaphysis and both epiphyses together (epiphyseal closure).
    • Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate).

  • Stages of Bone Development

    • Secondary ossification occurs after birth and forms the epiphyses of long bones and the extremities of irregular and flat bones.
    • The diaphysis and both epiphyses of a long bone are separated by a growing zone of cartilage (the epiphyseal plate).
    • When the child reaches skeletal maturity (18 to 25 years of age), all cartilage is replaced by bone, fusing the diaphysis and both epiphyses together (epiphyseal closure).

  • Hormonal Abnormalities and Height

    • Acromegaly is a syndrome that results when the anterior pituitary gland produces excess growth hormone (GH) after epiphyseal plate closure at puberty.
    • The distinction between gigantism (occurring in children) and acromegaly (occurring in adults) can be made by the occurrence of the adenoma in relation to the closure of the epiphyses.
    • If elevated growth hormone levels occur before the closure of the epiphyses (i.e. in prepubertal children), then gigantism ensues.
    • If it occurs after the closure of the epiphyses (i.e., in adults), then acromegaly ensues.

  • Cartilaginous Joints: Synchodroses

    • The epiphyseal plate is a hyaline cartilage plate in the metaphysis at each end of a long bone.
    • The epiphyseal plate is found in children and adolescents.
    • This process leaves only a thin epiphyseal scar that later disappears.
    • In adults who have stopped growing, the plate is replaced by an epiphyseal line.
    • Those with achondroplasia (a form of dwarfism) have premature closure of the epiphyseal growth plates, which results in shorter than average arms and legs.

  • Pituitary Gland Disorders

    • The distinction between gigantism (occurring in children) and acromegaly (occurring in adults) can be made by the occurrence of the adenoma in relation to the closure of the epiphyses.
    • If elevated growth hormone levels occur before the closure of the epiphyses (i.e. in prepubertal children), then gigantism ensues.
    • If it occurs after the closure of the epiphyses (i.e., in adults) then acromegaly ensues.

  • Puberty

    • The male "growth spurt" also begins later, accelerates more slowly, and lasts longer before the epiphyses fuse.
    • While estradiol promotes growth of breasts and uterus, it is also the principal hormone driving the pubertal growth spurt and epiphyseal maturation and closure.

  • Growth of Bone

    • The epiphyseal plate is the area of growth in a long bone.
    • On the epiphyseal side of the epiphyseal plate, cartilage is formed.
    • All that remains of the epiphyseal plate is the epiphyseal line .
    • As a bone matures, the epiphyseal plate progresses to an epiphyseal line.
    • (b) Epiphyseal lines are the remnants of epiphyseal plates in a mature bone.

  • Electrocyclic Reactions

    • The electrocyclic ring closure is is designated by blue arrows, and the ring opening by red arrows.
    • In the first case, trans,cis,trans-2,4,6-octatriene undergoes thermal ring closure to cis-5,6-dimethyl-1,3-cyclohexadiene.
    • The sterospecificity of this reaction is demonstrated by closure of the isomeric trans,cis,cis-triene to trans-5,6-dimethyl-1,3-cyclohexadiene, as noted in the second example.
    • This mode of reaction is favored by relief of ring strain, and the reverse ring closure (light blue arrows) is not normally observed.
    • Photochemical ring closure can be effected, but the stereospecificity is opposite to that of thermal ring opening.

  • Development of Joints

    • Between the epiphysis and diaphysis (the long midsection of the long bone) lies the metaphysis, including the epiphyseal plate (growth plate).
    • 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.
    • For example, the head of the femur (which is a part of the hip joint complex) is a pressure epiphyses.
    • These epiphyses assist in transmitting the weight of the human body and are the regions of the bone that are under pressure during movement or locomotione.
    • Image shows the location of the epiphyseal plates (or lines) and the articular surfaces of long bones.

  • Nerve and Blood Supply

    • The articular and epiphyseal branches of the neighboring arteries form a periarticular arterial plexus.
    • It supplies the capsule, synovial membrane, and the epiphyses.
    • After epiphyseal fusion in the growth of long bones, communication between the circulosus vasculosus and the end arteries of the metaphysis is established.