Bird skeleton
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The avian (bird) skeleton is highly adapted to these animals' capacity for flight. It is extremely lightweight, but strong enough to withstand the stresses that a bird experiences when taking off, flying and landing. One of the adaptions that make this possible is the fusing of bones that are separate in mammals into single ossifications, such as the pygostyle. Because of this, birds usually have a smaller number of bones than mammals or reptilians.
Birds have many bones that are hollow, with criss-crossing struts or trusses (cross walls) for structural strength. (Some flightless birds like penguins have only solid bones, however). The number of hollow bones varies from species to species, though large gliding and soaring birds tend to have the most. Birds also have more cervical (neck) vertebrae than many other animals; most have a highly flexible neck that consists of 13 to 25 vertebrae. Birds are the only vertebrate animals to have a fused collarbone (the furcula or wishbone) or a keeled breastbone.
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Skull
The skull is made up of 5 major bones:
- Frontal (top of head)
- Parietal (back of head)
- Premaxillary and Nasal (top beak)
- Mandible (bottom beak)
Neck, Back, and Tail
Made up of vertebrae, the vertebral column is divided into 3 sections:
- Cervical (13-16) (neck)
- Synsacrum (fused vertebrae of the back, also fused to the hips (pelvis))
- Pygostyle (tail)
Chest
The chest is made up of the furcula (wishbone), coracoid (collar bone) and ribs, which meet at the sternum (center of the chest).
Wings
The shoulder is made up of the scapula (shoulder blade), coracoid (see The Chest), and humerus (upper arm). The humerus joins the radius and ulna (forearm) to form the elbow. The carpometacarpus forms the equivalent of the hand on the wing with digits (fingers) extending into the wing. Hips
The hips are made up of the pelvis which includes 3 major bones
- Illium = top of the hip
- Ischium = sides of hip
- Pubis = front of the hip
Legs
The upper leg consists of the femur. At the knee joint, the femur connects to the tibiotarsus (shin) and fibula (side of lower leg). The tarsometatarsus forms the upper part of the foot, digits make up the toes.
