6 4 



ELEMENTS OF PHYSIOLOGY 



above by a long cartilage. The last two pairs are called 

 floating ribs, since the front ends are not attached to a bone 

 either directly, like the true ribs, or indirectly, like the false 

 ribs, but rest in the muscular walls of the waist. (Describe 

 the microscopic structure of cartilage as shown in Fig. 43.) 



107. The Appended Skeleton. This part of the skeleton 

 consists of the four limbs and the bones which serve to 

 attach them to the trunk or axial skeleton. 



108. Shoulder Girdle. The arms are attached to the 

 trunk by the shoulder girdle. This consists (Fig. 49) of 



four bones, two on each side, 

 the scapulae, or shoulder 

 blades, and the clavicles, or 

 collar bones. Each shoulder 

 is composed of a clavicle 

 ( " key," from its resem- 

 blance to the ancient form 

 of that article) and a scap- 

 ula (Fig. 59). The scapula 

 (a "trowel") occupies the 

 rear part of the shoulder. 

 It is a large flat bone, of 

 triangular shape, and bears 

 in the end at the angle 

 of the shoulder a shallow 

 socket into which is fitted the end of the upper bone of the 

 arm. The clavicle is a slender bone, round and slightly 

 curved, which occupies the front of the shoulder, and is 

 joined at one end to the scapula and at the other to the 

 sternum. The clavicles can be felt at the right and left 

 of the base of the neck. 



109. The Arm consists of the upper arm, forearm, wrist, 

 and hand (Fig. 60). The upper arm extends to the elbow 

 and has only one bone, the humerus. From the elbow to 

 the wrist is the forearm, formed of two bones, arranged 



FlG. 59. Clavicle, Scapula, and Head 

 of Humerus. 



Disjointed and seen from behind. 



