28 ANATOMY OF THE RABBIT 



ever, only the first seven of these costal cartilages articulate 

 with the sternum. 



The sternum (breastbone, Fig. 8) of the rabbit is comprised 

 of six bones; a manubrium, four sternebrae and a xiphoid 

 process (ensiform cartilage). In man the four sternebrae 

 (segments) fuse to form the body of the sternum. The cartilag- 

 inous ends of the first pair of ribs articulate directly with the 

 sides of the manubrium; the second to fifth pairs articulate 

 with the intersternebral cartilages of the manubrium and the 

 first to third sternebrae and the sixth and seventh pairs articu- 

 late with the cartilage between the fourth sternebra and 

 xiphoid process. 



d. THE PECTORAL GIRDLE AND SUPERIOR LIMB 



The pectoral (shoulder) girdle is comprised of two paired 

 bones, the scapula and clavicle. Right and left clavicles are 

 attached to the manubrium and scapula by ligaments, thus the 

 right and left halves are united to form the ventral portion of 

 the girdle. 



The scapula is attached to the trunk by muscles, except for 

 the ligaments and clavicle. The general topography of the 

 lateral and glenoid regions of the scapula is sufficiently well 

 show^n in figure lo to serve as a guide in studying this bone. 

 The medial side* of the fiat portion of this bone forms the 

 subscapular fossa, and the spine divides the lateral side of 

 the blade into a supraspinous and an infraspinous fossa. These 

 three fossae furnish surfaces for the attachment of three large 

 muscles which are named after the respective fossae. The 

 clavicle is rudimentary. 



The brachium has a single bone, the humerus (Figs, ii, 

 12). Its proximal end bears five important topographical 

 points for articulation or for muscle attachment. The large 

 head which articulates with the glenoid cavity of the scapula, 

 the lesser (medial) tuberosity, the greater (lateral) tuberos- 

 ity, from which the deltoid ridge extends along the laterocranial 



