44 ANATOMY OF THE DOMESTIC FOWL 



posterior haK of the glenoid cavity, or cavitas glenoidalis, in which 

 the humerus articulates and the processus coracoideus. 



The Clavicle. Location. — The clavicles, commonly known as the 

 wish bone, are located in the anterior chest region. 



Description. — The clavicles are long, slender bones uniting below 

 in the hypocledium, a laterally flattened process^. They are joined 

 to the upper end of the coracoid by fibrous cartilage. The hypocle- 

 dium is joined to the anterior point of the sternum by the claviculo- 

 sternal ligament. The clavicles, as united by the hypocledium, 

 form a v-shaped structure called the furculum, or, popularly, the 

 wish bone. 



The forks play the part of an elastic spring, whose office it is to 

 prevent the wings from coming toward each other during contraction 

 of the depressor muscles. The conformation of this bone is, there- 

 fore, like the sternum, related to the extent and power of flight; 

 and for this reason it is that, in swift flyers, the two branches of the 

 furculum are thick, solid, widely separated, and curved like a U; 

 while in those that fly heavily and with difficulty, these branches are 

 tliin and weak, and join at an acute angle. The latter formation 

 greatly diminishes its strength, and lessens, in a singular manner, 

 the reactionary power of the bony arch it represents. 



The Coracoid. Location. — The coracoid is located just back of 

 the clavicle and at the side of the entrance of the thoracic cavity. 

 It is the strongest bone of the shoulder girdle, extending upward, 

 outward, and forward. It articulates inferiorly with the sternum 

 and superiorly with the humerus and the scapula, and is attached 

 to the superior end of the furcular limb by a fibrous cartilage. 



Description. — It is thinnest in the center or shaft and broadens 

 toward the inferior extremity. The upper hook-like part of the 

 coracoid forms the fore part of the glenoid cavity, and together with 

 the scapula and furcula form the foramen triosseum through which 

 passes the tendon of the elevator muscle of the wing. The upper 

 end flattens out into three tuberosities, the tuberositas furcularis 

 which is thick and to which attaches the limb of the furcula, the 

 tuberositas scapularis which unites to the scapula, and the tuberosi- 

 tas humeralis which lies between these and articulates with the 

 humerus. 



THE FORE LIMB 



The bones of the fore limb are humerus, ulna, radius, carpus, 

 metacarpus, and phalanges. 



