Birds - are animals that not only move along the ground, but rose into the air, floating in the sky.Therefore, as a result of evolutionary change in the observed mass and shape of their bodies.This went on the accumulation of fat - margins, reduced friction during the motion, build muscle mass.At the same time changes their skeleton and muscles, i.e.Musculoskeletal system of birds.
Largely it is the same as in mammals.Musculoskeletal system consists of a bird of the axial skeleton, skull, shoulder and forearm bones, shoulder blades, thoracic vertebrae, pelvic bones and femur, etc.
At the same time, it is quite different than the musculoskeletal system of mammals.For example, the head of small birds, asAll the bones are fused cranial, and their number has decreased.Skull greatly facilitated due to the fact that the bone is mainly hollow and has toothless beak, which is covered only horn cover.Birds have curves of the spine, as in humans.Breast "human" cells expanded, and the animals and birds it is laterally compressed.
Cervical skeleton birds 11-25 presented free vertebrae, but the vertebrae of the thoracic firmly bonded to each other and at the same time with the lumbar vertebrae.Lumbosacral merged with the belt of the hind limbs, and formed the sacrum.
There is a difference in the facial skeleton and the belt extremities, and within the limbs.For example, only birds have the keel - cartilage outgrowth, which was formed in the accretion of the clavicle to the sternum.At flying birds sternum developed strongly enough, and the keel - large.
Musculoskeletal system includes the hind limbs of birds, which are the two big, strong pelvic bones fused with complex sacrum.And since the bird walks on two legs, the pelvis is also very powerful.The sacrum is formed by fused sacral, lumbar, caudal vertebrae, so I think that the lumbar birds there.
skeleton skeletons of birds differ from other animals in that he is strong and lightweight.This is achieved, firstly, because the tubular bones of birds.Second, the ease of oral bone explained.Therefore, the mass of the skeleton of a bird somewhere 5 to 15% by weight of her body.Except for the cervical spine, the entire spine is fixed.
As the front legs as a result of evolutionary development have turned into wings, the brush is almost not developed.But the birds that fly well, the large pectoral muscles make up somewhere 15-20% by weight, and a special arrangement contributes to the stability of the birds in the air.
standing below the level of development than birds and mammals, is the class of reptiles.The body consists of a reptile head, necks, trunk and limbs, except snakes and legless lizards, which of course denied.By building musculoskeletal system similar to the amphibious reptile, but unlike them, it has a stiff skeleton.A more progressive structure of the skeleton and muscles of these animals determined their mobility.The skeleton of reptiles, as well as musculoskeletal system of the birds, too, consists of the cervical, thoracic, sacral and caudal region.Long edges are connected to the sternum and rib cage is formed.
Reptiles, unlike other animals, have a dissected muscles, particularly the intercostal muscles.They can adjust the volume of the chest, compress and expand it, thus making the process of breathing.Since reptiles ribs end free, it allows them to swallow quite a large meal.They watered developed caudal section.
Summing up, it may be noted that the skeletons of the animals have distinctive features, but perform similar functions.They serve as a support body, protects internal organs, and help to move around in the living space.
