Wing (bird)

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Wings of a red-tailed buzzard
1   thumb (digitus alulae)
2   terminal phalanx of digitus major
3   basic phalanx of digitus major
4   digitus minor
5 + 6   carpometacarpus, a bone made of fused carpal and metacarpal bones, the two parts are called:
    5   os metacarpale minus
    6   os metacarpale majus
7   os carpi ulnare (   Carpal bones on the ulna)
8 os carpi radiale (carpal bones on the spoke)
9   spoke (radius)
10   ulna (ulna)
11   humerus (humerus)
12   raven bones or raven bones (coracoid)
13   shoulder blade (scapula)

Wings are movement organs used for flying in birds , which are created by reshaping the front limbs . When flying , they generate lift and propulsion.



The wings of the birds are transformed front extremities, the wing skeleton therefore, like the front extremities of other terrestrial vertebrates, consists of an upper arm bone ( humerus ), the forearm bone ulna ( ulna ) and spoke ( radius ) and the hand bone . In adapting to the changed function of flight, these bones have changed significantly.

When the wing is in place, the usually strongly developed humerus is positioned horizontally. The ulna is stronger than the radius and serves as the insertion point for the arm swing . The ulna is anterior to the radius , both bones are parallel to the humerus with the wing attached .

Fly membranes and wing muscles of a goose
Propatag.  Propatagium, anterior
skin metapatag.  Metapatagium, posterior  flight
Lig. Marginal
ligament Elast. sec.  connective tissue band that holds the arm and hand  wings in position
Exp. sec. Expansor secundariorum
Pt. lg.  Tensor patagii longus muscle
Pt. br.  Musculus tensor patagii brevis
Bi.  Musculus biceps brachii
Triceps  brachii pector muscle .  Pectoralis muscle

The bones of the hand have experienced the greatest changes.

  • Of the numerous carpal bones ( ossa carpi ) in other vertebrates, only two remain, the os carpi radiale and the os carpi ulnare .
  • The distal carpal bones ( ossa carpalia distalia ) that are still created during development grow together on the one hand and with the proximal (close to the body) ends of the originally three metacarpal bones ( ossa metacarpalia ), which thus form only one bone, to form the carpometacarpus . The carpometacarpus forms a bone brace. The thicker branch of this clasp (presumably the second metacarpal bone) is called the greater metacarpal bone , the thinner branch (presumably the third metacarpal bone) is called the minor metacarpale .

The number of fingers is reduced to three:

  • The thumb ( digitus alularis ) consists of only one finger bone , the phalanx digiti alulae .
  • A larger finger, the digitus major , consists of two finger bones ( phalanx proximalis and phalanx distalis digiti ).
  • A little finger, the digitus minor , consists of a bone ( phalanx digiti minoris ).

The wings 1 to 6, counted from the inside out, start at the carpometacarpus , the wings 7 to 10 at the two finger bones of the digitus major .

Flying membranes

1 hand swing, 2 hand covers, 3 thumb feathers, 4  arm wings, 5  large arm covers, 6  medium arm covers, 7  small arm covers, 8  umbrella springs, 9  shoulder springs

Flying membranes brace the different wing parts together, fill the spaces between the bones and limit the wing core to the front and back. The most important are the anterior flight membrane, the posterior flight membrane and the large marginal ligament between the elbow and metacarpal bones.


The wing feathers are the largest feathers on the wing and are divided into hand wings and arm wings depending on where they are inserted . A band of connective tissue holds them in place. They interlock like roof tiles. The two feather vanes are unevenly wide, so that the draft leads to the fact that the feathers turn upwards when thrown so that the air can pass between the flight feathers. When the wing flaps down again, they turn back and form a closed surface. The flight feathers are usually greatly reduced in flightless birds .

The flight feathers are covered by several rows of smaller covers at the bases , so that a complete closure of the wing is created.

The small feathers on the leading edge of the wing, carried by the thumb, are called the thumb wing or alula and are used for steering and braking at high airspeeds.

Seen from above, the folded wings are largely covered by the umbrella feathers .

Muscles, tendons and ligaments

Both the superficial pectoralis muscle, which lowers the wing, and the supracoracoid pectoral muscle, which lifts the wing, attach to the sternum.

About 50 different muscles contribute to the movements of the wings. The two largest of these are called pectoral muscles and attach to the sternum crest ( crista sterni ). The pectoralis major muscle or pectoralis superficialis muscle lies superficially . When it contracts, the wing is pulled down and rotated forward and down. It is the bird's largest muscle.

The small pectoral muscle ( pectoralis minor , pectoralis profundus or supracoracoid muscle ) lies below the surface directly above the ribs and runs from the sternum through the three-bone hole ( foramen triosseum ) to the top of the upper arm bone ( humerus ). The three-bone hole lies between three bones of the shoulder joint, i.e. between the raven bone ( coracoid ), the shoulder blade ( scapula ) and the fork bone ( furcula ). When the pectoralis minor contracts, it lifts the wing.

The small pectoral muscle is supported by the deltoid muscle ( Musculus deltoideus ), which pulls the wing directly upwards without a force diversion through the three-bone hole and at the same time reverses the rotation of the wing downwards and forwards. In addition, the deltoid muscle tightens the anterior flight membrane. The deltoid is composed of two parts, the deltoideus anterior and the deltoideus posterior . In songbirds, its main proportion is greatly reduced or absent.

There are many smaller muscles on the wing itself that control the exact position of the wing. The rhomboideus muscle pulls the wing forward, latissimus dorsi muscle pulls the wing backwards. The biceps brachii and triceps brachii muscles pull the wings forward and backward. Extensor carpi and flexor carpi muscles stretch and bend the wrist. The fingers are stretched and flexed by the extensor digiti and flexor digiti muscles. Other muscles move the individual fingers.


With the help of the springs, a streamlined profile (see wing ) is created. In gliding flight (no active wing flapping) there is a slight overpressure on the underside and a strong negative pressure on the top, which pulls the wing and thus the bird upwards. A technical implementation of the bird flight takes place in the ornithopter .



  • Gerhard Hummel, Christiane Haupt: anatomy and physiology of birds. UTB, 2144 / Ulmer, Stuttgart 2000, ISBN 3-8252-2144-X , pp. 30-33 and 202-203.

Web links

Commons : Bird wings  - collection of images, videos and audio files
Wiktionary: Fittich  - explanations of meanings, word origins, synonyms, translations
Wiktionary: wing  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. a b c d Georg Rüppell: Vogelflug. Kindler, Munich 1975, ISBN 3-463-00611-1 , p. 38.
  2. ^ A b Hans-Heiner Bergmann: The biology of the bird. Aula, Wiesbaden 1987, ISBN 3-89104-447-X , p. 83.
  3. a b c Einhard Bezzel, Roland Prinzinger: Ornithology. 2nd Edition. Ulmer, Stuttgart 1990, ISBN 3-8001-2597-8 , p. 25.
  4. a b Josselyn van Tyne, Andrew J. Berger: Fundamentals of Ornithology. 2nd Edition. Wiley, New York 1976, pp. 49 and 386-389.