THE PIGEON 19 1- 



In order to avoid cutting the muscles and other organs beneath 

 the skin, make this incision with scissors, lifting up the skin with 

 forceps and then cutting it. Take special care not to cut the large, 

 thin-walled crop, which lies in contact with the skin at the base 

 of the neck, or the large blood vessels and nerves in the neck and 

 the wings. Note the thinness and delicacy of the skin. 



The great pectoral muscles, which depress the wings during 

 flight, form a large part of the breast. They lie along the entire 

 length of the keel of the breastbone and constitute the lateral and 

 anterior surfaces of the trunk. A prominent tendon will be seen 

 running through the midst of the muscle to the shoulder on each 

 side; it passes over the shoulder and finds its insertion on the 

 upper and outer surface of the humerus, as will be seen when 

 the muscle is dissected. 



Posterior to the pectoral muscles are the abdominal muscles, 

 which form the ventral and lateral body walls of the abdomen. 

 In the midventral line, where the membranous tendons of the 

 abdominal muscles of the right and left sides meet, is a prominent 

 white line, the linea alba. 



Make a transverse incision in the middle of the great pectoral, 

 dividing it into an anterior and a posterior half. Be careful not 

 to cut too deeply, or the lesser pectoral will be injured. 



Note the large blood vessels in the muscle. Beneath the great 

 pectoral lies the lesser pectoral muscle, which fills the angle be- 

 tween the keel and the body of the breastbone. Remove from 

 the body that portion of the great pectoral back of this incision, 

 being careful not to cut the lesser pectoral, and note its attachment 

 to the ventral portion of the keel and the lateral portions of the 

 body of the breastbone. Dissect the anterior half of the great 

 pectoral, from the incision forward, separating it from the lesser 

 pectoral, the breastbone, and the. clavicle (the wishbone), until 

 the large tendon at its forward end is reached. Be careful in doing 

 this not to cut or injure any of the bones. Follow the tendon to its 

 insertion in the dorsal side of the humerus. A broad shoulder 

 muscle, the anterior head of the biceps, covers this tendon. 



Note the tendon which runs through the middle of the lesser 

 pectoral muscle to the shoulder. Free the muscle from its attach- 



