Locomotion in bird

• Most birds have approximately 175 different muscles, mainly controlling the wings, skin and legs.
• During flight, a bird moves its wings in weak upstrokes and strong downstrokes to get lifted and fly in the air.
• The antagonistic muscle pair of pectoral and supracoracoideus forms the major flight muscles.
• Both muscles are attached to the breast bone (sternum) but the pectoral muscles contract to cause downstroke of the humerus bone of the wings while the supracoracoideus causes the upstroke of the wings, providing lift.
• In addition, circular movement of the wings, forward and then backward, during each downstroke, provides thrust that moves the bird forward through the air.