THE FROG 5 



the attachment of muscles. From its anterior margin the anterior 

 cornua pass outwards, then backwards, and lastly upwards to 

 connect with the prootic, while the posterior cornua arise from 

 the posterior margin of the body and pass outwards and back- 

 wards on either side of the larynx. 



Draw the Hyoid, X4. 



Shoulder-girdle and Sternum. These form an incomplete ring 

 or girdle around the body, but are without direct connection with 

 the axial skeleton. The girdle may be divided into dorsal and 

 ventral halves by the socket, glenoid fossa, for the articulation 

 of the fore limb. Dorsal to the fossa is the scapula, which is 

 surmounted by the suprascapula, composed partly of bone, 

 partly of cartilage. Does the scapula contribute to the forma- 

 tion of the glenoid fossa? 



Below the fossa are two bones on either side, extending 

 towards the median line, an anterior clavicle and a posterior 

 coracoid bone, including between them an opening, the coracoid 

 fontanelle. Connected with the clavicle is a cartilaginous bar, 

 the procoracoid, not usually easily seen in the prepared skeleton. 



Clavicles and coracoids of the two sides are connected in 

 the middle line by the sternal structures. Of these, in the prepared 

 skeleton, the following parts may be made out. Joining the 

 clavicles in front, an omosternum, and in front of this an epister- 

 num. Behind the coracoids is the sternum proper, terminated by 

 abilobed xiphisternum. 



Draw this apparatus, turning the scapula and suprascapula 

 outwards in the sketch, so that all parts may be seen in a ventral 

 view. 



In the fore limb make out and draw the following parts. In 

 the region of the upper arm a long bone, the humerus, with en- 

 larged articular processes on either end. On its inner or under 

 surface is a strong ridge, the crista deltoidea, for the attachment 

 of the deltoid muscle. On the posterior distal angle of the 

 humerus, beside the articular surface, is a prominent trochlear 

 process. 



The skeleton of the forearm is composed of the coalesced 

 radius and ulna (radio-ulna or os antebrachii), the radius being on 

 the anterior side. Notice the shape of the articular face of the^ 

 proximal end of this bone. Its size is increased by a projecting; 

 olecranon process. 



