Meckel's cartilage


Meckel's cartilage
Meckel's cartilage
Gray43.png
Head and neck of a human embryo eighteen weeks old, with Meckel’s cartilage and hyoid bar exposed.
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Mandible of human embryo 95 mm. long. Inner aspect. Nuclei of cartilage stippled.
Latin cartilago arcus pharyngei primi
Gray's subject #13 66
Precursor first branchial arch
Gives rise to incus, malleus
Code TE E4.0.3.3.3.1.3

The cartilaginous bar of the mandibular arch is formed by what are known as Meckel’s cartilages (right and left) also known as Meckelian cartilages; above this the incus and malleus are developed.

The dorsal end of each cartilage is connected with the ear-capsule and is ossified to form the malleus; the ventral ends meet each other in the region of the symphysis menti, and are usually regarded as undergoing ossification to form that portion of the mandible which contains the incisor teeth.

The intervening part of the cartilage disappears; the portion immediately adjacent to the malleus is replaced by fibrous membrane, which constitutes the sphenomandibular ligament, while from the connective tissue covering the remainder of the cartilage the greater part of the mandible is ossified.

Johann Friedrich Meckel, the Younger discovered this cartilage in 1820.

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

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Evolution

The Meckelian Cartilage, also known as "Meckel's Cartilage", is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first gill arch (nearest the front) in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw.[1]

In early fish and in chondrichthyans (cartilaginous fish such as sharks, which are not primitive in any sense of the word), the Meckelian Cartilage continued to be the main component of the lower jaw. But in the adult forms of osteichthyans (bony fish) and their descendants (amphibians, reptiles, birds, mammals), the cartilage was covered in bone - although in their embryos the jaw initially develops as the Meckelian Cartilage. In all tetrapods the cartilage partially ossifies (changes to bone) at the rear end of the jaw and becomes the articular bone, which forms part of the jaw joint in all tetrapods except mammals.[1]

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References



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Look at other dictionaries:

  • Meckel's cartilage — Meck·el s cartilage mek əlz n the cartilaginous bar of the embryonic mandibular arch of which the distal end ossifies to form the malleus and most of the rest disappears in development, with the part adjacent to the malleus being replaced by… …   Medical dictionary

  • Meckel's cartilage — Meckelian Meck*e li*an, a. (Anat.) Pertaining to, or discovered by, J. F. Meckel, a German anatomist. [1913 Webster] {Meckelian cartilage}, the cartilaginous rod which forms the axis of the mandible; called also {Meckel s cartilage}. [1913… …   The Collaborative International Dictionary of English

  • Meckel's cartilage — a cartilaginous bar in the fetus around which the mandible develops. Part of Meckel s cartilage develops into the malleus (an ear ossicle) in the adult. [F. Meckel, the Younger (1781–1833), German anatomist] …   The new mediacal dictionary

  • Meckel's cartilage — the functional lower jaw of Elasmobranchii and Holocephali, the embryonic lower jaw of other gnathostomous vertebrates which ossifies at least in part as the mentomeckelian, mediomeckelian, coronomeckelian, articular and retroarticular. It… …   Dictionary of ichthyology

  • meckel's cartilage — ˈmekəlz noun Usage: usually capitalized M Etymology: after Johann F. Meckel died 1833 German anatomist : the cartilaginous axis of the mandibular arch forming no part of the jawbone but sometimes giving rise to the articular and the bones of the… …   Useful english dictionary

  • Хрящ Мандибулярной Дуги Эмбриона (Meckel'S Cartilage) — полоска хрящевой ткани у эмбриона, вокруг которой происходит развитие его нижней челюсти. Из части этого хряща у людей формируется молоточек (косточка внутреннего уха). Источник: Медицинский словарь …   Медицинские термины

  • Meckel, Johann Friedrich — born Oct. 17, 1781, Halle, Prussia died Oct. 31, 1833, Halle German anatomist. He was the first to describe the embryonic cartilage (Meckel cartilage) that becomes part of the lower jaw in fishes, amphibians, and birds and also described a… …   Universalium

  • Meckel-Gruber syndrome — Meck·el Gru·ber syndrome mek əl grü bər n a syndrome inherited as an autosomal recessive trait and typically characterized by occipital encephalocele, microcephaly, cleft palate, polydactyly, and polycystic kidneys called also Meckel s syndrome… …   Medical dictionary

  • Meckel's foramen — when not completely surrounded by dermal bone, Meckel s cartilage is visible on the medial face of the lower jaw, e.g. some Sarcopterygii. Also called Meckel s or Meckelian canal, groove and fossa although groove is usually used in tetrapods …   Dictionary of ichthyology

  • Cartilage — Firm, rubbery tissue that cushions bones at joints. A more flexible kind of cartilage connects muscles with bones and makes up other parts of the body, such as the larynx and the outside parts of the ears. * * * A connective tissue characterized… …   Medical dictionary