THE FROG'S SKELETON 



For this study prepared skeletons are provided. They arc 

 fragile and therefore must be handled with care. The value 

 of each is such that a charge must be made for any breakage 

 which is the fault of the user. 



The need of a firm and, at the same time, flexible support for 

 the body is apparent in considering such functions as locomotion 

 in which rigid support and precision of movement are paramount. 

 Such functions, as well as many others, reside in the skeletal 

 framework of the body. The skeleton as a whole comprises two 

 main divisions: (o) the axial skeleton and (6) the appendicular 

 skeleton. 



Axial Skeleton. — Extending along the middle line or main 

 axis of the body there are found the skull and vertebral column 

 constituting the axial skeleton. 



The Skull. — Recalling the shape of the frog's head examine the 

 skull and determine the various aspects (i.e., dorsal, ventral, 

 cephalic, caudal, lateral). The most conspicuous feature of the 

 skull is the presence of a relatively enormous and somewhat 

 rectangular space on either side of the middle port on. These 

 spaces mark the location of the eyes and are known as the orbits. 

 Through two smaller spaces immediately cephalad of the orbits 

 the nostrils open. 



The skull placed at the cephalic end of the axial skeleton 

 comprises (a) the cranium which encloses the small brain and 

 occupies the mesal region between the orbits. Associated with 

 the cranium are combinations of bones and cartilages forming 

 protecting encasements for certain sense organs. These are 

 called "sense capsules." They occur in pairs: the olfactory 

 capsules surrounding the olfactory organs at the cephalic end of 

 the cranium and the auditory capsules on either side at the caudal 

 end. (6) the visceral skeleton includes the framework of the jaws 

 and hyoid apparatus (tongue support). In the caudal end of 

 the cranium is an opening, the foramen magnum, through which 

 the spinal cord extends from the brain. Note the lines (sutures) 

 formed by the meeting of bones. Determine the location of 

 teeth. Identify the slender bone, columella, connecting the 



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