122 



simple diagonal locomotion, such as the trot of 

 the horse, the gathering of one pair of lines, and 

 the discharge of the other pair, are to some degree 

 synchronous, and must be described together. 



We shall next enter into a more detailed ex- 

 amination of the action of various parts. 



§ 120. The long tube, called ihe tvindpipe, is, 



during locomotion, the subject of various twisting 



movements, coming from the motions imparted to 



the lobes of the lungs by the varying shapes of 



the chest. These twistings are not communicated 



to the larynx, or voice box, because the windpipe, 



just below the plane at which the larynx crowns 



it, is held up by two loops, one on either side, and 



these slip on cords stretched from the back part 



of the under surface of the skull behind the head 



condyle joints, to the inside-front of the lower 



jaw, on a line between the two central incisor 



teeth. These cords, which are each composed of 



two muscular masses, joined together in the centre 



where the loops run by a smooth, round tendon, 



have been already mentioned as the Digastrics. 



Being joined to the skull behind the head condyles, 



to the lungs by the windpipe, and to the lower 



jaw, they obviously connect the motions of all 



three. 



