Wednesday, 10 April 2013

#416 In the studio: Bird anatomy, con't . . .

Please start this bird anatomy series with post #403, March 10.

Most birds are designed for flight and flying demands a rigid airframe.   The bird's rib cage and backbone are fused together . . . only the neck, tail, and wings are flexible.  The spine of mammals - human and quadruped - is supple.  A bird's spine is rigid . . . 
if it were supple, the bird would lose control and could not fly. 

The bird's bones are hollow, light, and remarkably strong.  For instance, a pelican weighs twenty pounds and the skeleton weighs only twenty-three ounces.  Nature has sluffed off weight to enable flight.  

The skeleton of a bird can be summarized as follows:  
    1 - the skull, made up of fused bones  
    2 - the vertebral column; includes 13-25 neck vertebra, fused backbone vertebra, flexible tail vertebra   
    3 - the hip girdle which provides support for the legs and where the leg muscles attach  
    4 - the pygostyle, where the tail feathers attach  
    5 - the sternum or keel, which anchors the wing pectoral muscles of flying birds  
    6 - the wing, includes the humerus, radius/ulna, and hand which anchors the primary flight feathers  
    7 - the leg - includes the femur, tibia, tarsus, and toes  
    8 - the clavicle or wishbone, which keeps the wing joint and coracoid in position as the wing muscles 
         pull downward.

A bird's entire body, except is bill and feet, is usually covered with feathers.  Why is the skeleton important to the bird sculptor?  The bird sculptor must know how the bones are arranged, how they articulate, and the limitations of skeletal movement before attempting to define muscles and feather groups.  

Copyright - Sandy Scott

Below is an etching entitled Dominick - copyright Sandy Scott
The underlying skeleton can be seen above and is also illustrated in post #410

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