Polymelia Explained

polemilia
Synonyms:Hydra syndrome
Field:Medical genetics

Polymelia is a birth defect in which an affected individual has more than the usual number of limbs. It is a type of dysmelia. In humans and most land-dwelling vertebrates, this means having five or more limbs. The extra limb is most commonly shrunken and/or deformed. The term is from Greek πολυ- "many", μέλεα "limbs".

Sometimes an embryo started as conjoined twins, but one twin degenerated completely except for one or more limbs, which end up attached to the other twin.

Sometimes small extra legs between the normal legs are caused by the body axis forking in the dipygus condition.

Notomelia (from Greek for "back-limb-condition") is polymelia where the extra limb is rooted along or near the midline of the back. Notomelia has been reported in Angus cattle often enough to be of concern to farmers.[1]

Cephalomelia (from Greek for "head-limb-condition") is polymelia where the extra limb is rooted on the head.[2]

Origin

Tetrapod legs evolved in the Devonian or Carboniferous geological period from the pectoral fins and pelvic fins of their crossopterygian fish ancestors.Fish fins develop along a "fin line", which runs from the back of the head along the midline of the back, round the end of the tail, and forwards along the underside of the tail, and at the cloaca splits into left and right fin lines which run forwards to the gills. In the paired ventral part of the fin line, normally only the pectoral and pelvic fins survive (but the Devonian acanthodian fish Mesacanthus developed a third pair of paired fins); but along the non-paired parts of the fin line, other fins develop.

In tetrapods, only the four paired fins normally persisted, and became the four legs. Notomelia and cephalomelia are atavistic reappearances of dorsal fins. Some other cases of polymelia are extra development along the paired part of the fin lines, or along the ventral posterior non-paired part of the fin line.

Notable cases

Humans

Other animals

In mythology

Many mythological creatures like dragons, winged horses, and griffins have six limbs: four legs and two wings. The dragon's science is discussed in Dragons: A Fantasy Made Real. Additionally, angels are often depicted with two arms, two legs, and two wings.

In Greek Mythology:

Sleipnir, Odin's horse in Norse mythology, has eight normal horse legs, and is usually depicted with limbs twinned at the shoulder or hip.

Several Hindu deities are depicted with multiple arms and sometimes also multiple legs.

In popular culture

See also

Sources

External links

Notes and References

  1. Web site: Polymelia.
  2. A case of cephalomelia discovered in a baby born in Niger. 2015. 10.1007/s00381-015-2831-2. 28169410. Kelani. A. Bariath. Moumouni. H.. Younsa. H.. James Didier. L.. Hima. A. M.. Guemou. A.. Issa. A. W.. Ibrahim. A.. Sanda. M. A.. Sani. R.. Sanoussi. S.. Catala. M.. Child's Nervous System. 32. 1. 205–208. 26227339.
  3. Web site: The workes of that famous chirurgion Ambrose Parey - Digital Collections - National Library of Medicine . 2023-12-15 . collections.nlm.nih.gov.
  4. 10.1016/S0266-7681(97)80025-3. 9061534. Upper Limb Triplication with Radial Dimelia. Journal of Hand Surgery. 22. 1. 80–83. 1997. Mennen. U.. Deleare. O.. Matime. A.. 35811842.
  5. News: Three-armed boy 'recovering well' . . Quentin . Sommerville . 2006-07-06. 2016-12-22.
  6. News: Pennsylvania farm discovers a four-legged chicken. Associated Press. 2006-09-22 . 2006-09-22.
  7. Web site: This quadruped has feathers and clucks - US news - Weird news - Animal weirdness . NBC News . 2006-09-22 . 2016-12-22.
  8. Web site: Xinhua - English . News.xinhuanet.com . 2006-07-07 . 2016-12-22 . dead . https://web.archive.org/web/20161223132953/http://news.xinhuanet.com/english/2006-07/07/content_4806500.htm . 2016-12-23 .
  9. News: Five-Legged Dog Saved From Coney Island Freakshow. 2009-08-20. 2015-03-12 . Huffington Post.
  10. Book: "An Eight Legged Lamb" Scientific American: Supplement 1184. September 1898. Munn and Company. 18983. en.
  11. Web site: McCahill. Elaine. 2018-06-12. Mutant lamb with eight legs, two bodies and one head delivered by shocked farmer. 2021-11-06. mirror. en.