limbs

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As limbs (singular: the limb ) or extremities (from Latin extremus 'outermost'), in short also limbs (from Middle High German gelide , "limb, extremity, limb, penis"), paired body appendages moved by muscles are called in humans and animals , which consist of several sections (links).

Man's limbs are the arms and legs.

Terrestrial vertebrates

Arm skeleton of different animal species (each from left)
Top row: salamander, turtle, crocodile, bird.
Bottom row: bat, whale, mole, human.

Hand skeleton of various animal species
From left: orangutan, dog, pig, cattle, tapir, horse.

The limbs of the terrestrial vertebrates (also called tetrapods or quadrupeds) are the result of the paired pectoral and pelvic fins of certain meat-fins . The fins of the extinct genus Tiktaalik already show significant features of vertebrate extremities.

A distinction is made between a front or shoulder limb and a rear or pelvic limb, depending on how they are attached to the trunk . Here the skeleton of the hind limbs is directly connected to the spine via the pelvic girdle. The skeleton of the forelimbs is attached to the shoulder girdle, which only in some "higher" terrestrial vertebrates is in contact with the spine via the collarbone, breastbone and ribs. The limbs are used for locomotion or as a gripping tool ( arms ).

The front limb (also known as the upper extremity in humans) may have been transformed into the following forms:

• Legs, similar to the hind legs
• Arms with clasping hands .
• completely regressed in snakes and blindworms
• Bird wings , wings with flight membranes like those of the bats
• Flipper , the front fin of the cetaceans

The hind limb (also known as the lower extremity in humans ) can be transformed into the following shapes

• legs
  • Sole walker : With foot like with humans.
  • to hop like with the kangaroos
  • Toe walkers , often with claws
  • Pointed walkers , often with hooves , as in solipeds and the claws of the ungulates
• Birds : legs, with bird feet

The limb sections can be divided comparatively anatomically into different sections:

• Limb belt ( cingulate membrorum , see also Zingulum ), also called Zonoskelett designated: shoulder girdle ( cingulate membri thoracici ) and pelvic girdle ( cingulate membri pelvini )
• Limb column with:
  • Limb stalk ( Stylopodium ): upper arm or thigh
  • Zeugopodium or Zygopodium : forearm or lower leg
• Limb tip ( Autopodium ) with:
  • Basipodium : carpal or tarsus
  • Metapodium : metacarpal or metatarsus
  • Acropodium : fingers or toes

Arthropoda

Centipedes

The structure of the "feet" gave the trunk of the arthropods ( Arthropoda ) its name. The body of the original arthropod, similar to that of the centipede , was divided into largely undifferentiated, successive segments , each with a pair of limbs. In the course of the development of the tribe there was a differentiation of the segments and their limbs depending on the location. Thus, in modern arthropods in the header region a plurality of adjacent segments fused together, and the corresponding pairs of limbs can be sensory organs (eg. B. antennas ) and mouthparts transformed.

legs

See also : insect leg

Insect leg

• In insects, the thorax usually carries three pairs of legs, one on each of the three thoracic segments.
  • A catch leg is a leg that has been transformed for the purpose of catching prey in many groups of predatory insects, usually on the prothorax , the 1st thorax segment.
• The split leg is a special limb in crustaceans .
• The pair of legs of butterfly caterpillars and some other insect larvae located on the last segment of the abdomen is referred to as a pusher .

Construction of the leg

• Leg formula in arachnids
• The term coxa is the scientific name for the hip and is used in arthropods for the uppermost part of the leg.
• In the following joint there is the trochanter or thigh ring.
• The femur is the second uppermost section of the arthropod's leg , which is connected to the coxa by the trochanter.
• The tarsus is the subsequent section of the leg of the arthropod. It often consists of several parts (tarsi or tarsi).

Unlike the wings of terrestrial vertebrates, insect wings are not converted legs.

Antennas

→ Main article : Feelers (biology)

The limbs of the first and second head segments have often become antennas.

• The jaw-claw carriers (Chelicerata) have no extremities on their first head segment
• Flagellant antennas occur in all ectognathic insects. It is made up of the scapus (basal segment ), pedicellus (2nd segment) and a more or less changing number of antenna segments (flagellomeres).
• Link antennas are found in springtails and double tails . With the exception of the terminal limb, they contain muscles in all other limbs, which means that each limb can be moved individually.

Mouthparts

→ Main article : mouthparts

Mouth parts:
A grasshopper, B bee, C butterfly,
D mosquito (female)

The mouthparts of the Arthropoda are derived from the foremost pairs of legs of a hypothetical urarthropod and are therefore counted among the limbs.

• The characteristic feature of the jaw-claw bearer (Chelicerata) is called chelicere or jaw claw. This is the extremity of the 1st head segment that has been converted into a mouth tool.
• Insects:
  • Mandibles (they correspond to the upper jaw and their base link cardo ),
  • 1. Maxilla ( lower jaw ) with lower jaw probes (the first pair of mouth parts),
  • 2. Maxilla or labium (lower lip with lower lip probes).
  • The proboscis of many insects consists of the lower jaw (maxilla) that has grown together and changed with the labium.

• In some groups of mites , the extremities of the 3rd head segment, the pedipalps , are also used as mouth parts.
• In woodlice , the limbs of the 1st thoracic segment are transformed into maxillipedes .

More limbs

• Cercus : The cerci represent the extremities of the last abdominal segment in front of the telson and are also present in many taxa in which there are no or only rudimentary extremities on the remaining abdominal segments.
• The pleopods or leaf legs of the crustaceans serve as swimming legs and gills .

Limbs and limb-like structures of other animals

• Parapodium of annelids (Annelida) and polychaetes .
• The fins of the fish .
• The andropodium is an anal fin of the highland pike (Goodeidae) and half-beaked pike (Hemiramphidae) that has been transformed into a mating organ .
• As a tentacle is called elongated structures in different animals, so-called tentacles.

See also

• Akren - parts of the body that are far from the trunk
• Extremity development in tetrapods
• Extremity evolution in vertebrates

Web links

Wiktionary: Limb  - explanations of meanings, word origins, synonyms, translations

Wiktionary: extremity  - explanations of meanings, word origins, synonyms, translations

Individual evidence

1. ↑ Jürgen Martin: The 'Ulmer Wundarznei'. Introduction - Text - Glossary on a monument to German specialist prose from the 15th century. Königshausen & Neumann, Würzburg 1991 (= Würzburg medical historical research. Volume 52), ISBN 3-88479-801-4 (also medical dissertation Würzburg 1990), p. 131.