epiphyseal plate

Examples of epiphyseal plate in the following topics:

• Cartilaginous Joints: Synchodroses

  • A temporary form of joint called an epiphyseal (growth) plate, is one where the cartilage is converted into bone before adult life.
  • 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.
  • In puberty, increasing levels of estrogen, in both females and males, leads to increased apoptosis of chondrocytes in the epiphyseal plate.
  • In adults who have stopped growing, the plate is replaced by an epiphyseal line.

• 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 which is under pressure during movement or locomotion; hence, their name.
  • Image shows the location of the epiphyseal plates (or lines) and the articular surfaces of long bones.

• 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).

• Supply of Blood and Nerves to Bone

  • Near the epiphysis, they anastomose with the metaphyseal and epiphyseal arteries.
  • The blood supply of the immature bones is similar, but the epiphysis is a discrete vascular zone separated from the metaphysis by the growth plate.
  • Epiphyseal and metaphyseal arteries enter on both sides of the growth cartilage, with anastamoses between them being few or absent.
  • Image shows the location of the epiphyseal plates (or lines) and the articular surfaces of long bones.

• Structural Classification of Joints

  • The epiphyseal (growth) plates are examples of synchondroses.
  • Image demonstrates a synchondrosis joint with epiphyseal plate (temporary hyaline cartilage joint) indicated (a) and a symphysis joint (b).

• 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 of the cartilage is replaced by bone, fusing the diaphysis and both epiphyses together (epiphyseal closure).

• Gross Anatomy

  • The ends of epiphyses are covered with hyaline cartilage (articular cartilage).
  • At the cessation of growth, the epiphyses fuse to the diaphysis, thus obliterating the intermediate area known as the epiphyseal plate or growth plate.
  • These bones are expanded into broad, flat plates, as in the cranium (skull), ilium (pelvis), sternum, rib cage, sacrum, and scapula.

• 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.

• 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.

• Neurulation

  • This strip is called the neural plate, and is the origin of the entire nervous system.
  • The neural plate folds outwards to form the neural groove.
  • The anterior (ventral or front) part of the neural tube is called the basal plate; the posterior (dorsal or rear) part is called the alar plate.
  • In general, it entails the cells of the neural plate forming a cord-like structure that migrates inside the embryo and hollows to form the tube.
  • Transverse sections that show the progression of the neural plate to the neural groove from bottom to top.