163 ANATOMICAL TMCHNOLiUdX. 



CLAVIOULA (Fig. 30, 48, 66, 67, 73). 



The damole or collar bone is- briefly described in § 313. 



References. — Straus-Durckheim, A, I, 509 ; Flower, A, 388 ; Gegenbaur (Lankester), 

 A, 477 ; Gegenbaur, C ; Gray, A, 215-318 ; Quain, A, I, 84, 96 ; Parker, A, 215 ; Hum- 

 phrey, A, 359-368. 



^ 433. Explanation of Fig. 48. — This represents the unusually large and well 

 marked clavicles or collar bones of an old male cat. Their mesal or sternal ends are 

 apposed, and are seen to be approximately cylindrical. 



The left is placed in nearly its natural 

 TIKsaL J y^ attitude in the body, showing that its cephalo- 



-— -j'"'^"". ^^^^S^^^^ caudal diameter is nearly uniform, and that 



latkeal ' ^^ ^^^^^^tat- ^^''^ ^"'^ curves slightly caudad, the mesal 



_ ._ _ _ - _ end the more decidedly. 



Fig. 48. — The Right and Left Cla- „, . , . , , , , 



^ „ ^ The ngnt is so placed as to show the 



vicuL^ OF AN Old Cat ; x 1. , , ^ , ■,■ , ^-i j -i 



caudal aspect, and display the dorsal concav- 

 ity. The mesal half is nearly straight, but the lateral is quite regularly curved. The 

 dorso-ventral diameter of the bone increases gradually toward the lateral end, which is 

 about twice the width of the mesal. 



Directly or indirectly, the clavicle affords attachment to the Mm. daw-trapezius, daw- 

 maatoideus and davo-dettoideus, but as it is connected with the sternum and the scapula 

 only by ligaments, it is moved with the muscles instead of forming an efficient fulcrum 

 for their action. 



THE STERNUM (Pig. 7, 30, 50, 72, 73. 99, 100). 



The sternum or breast bone was briefly described in § 210. 



References.— Straus-Durckheim, A, I, 496, 497 ; Mivart, B, 49, SO ; Flower, A, 73 : 

 Humphrey, A, 331-339 ; Gray, A, 307-310 ; Quain, A, I, 35-27 ; Chauveau, A, 75 ; Chau- 

 veau (Fleming), A, 66 ; Leyh, A, 164-166 ; Parker, A, 215. 



§ 433. Explanation of Fig. 49. — The ventral aspect of an adult sternum, with the 

 contiguous parts of the costicartilagines. Incomplete views of the sternum are given in 

 Fig. 30, 50, 73, 73, 99 and 100. 



The sternum consists of a mesal series of osseous or partly cartilaginous segments 

 called sternehrcB, united by cartilages. The figure was drawn from a dried sternum, and 

 the intersternebral cartilages are not shown distinctly, neither is indicated the line of junc- 

 tion of the osseous and cartilaginous portions of the caudal segment. 



Of the stemebrse, the most cephalic and the most caudal have received special names, 

 presternum and xipJiisternum. The intervening segments constitute the mesosternum. 



§ 434. Mesosternum. — As indicated in § 310, there may be either 6 or 7 mesosternebrse, 

 making the total number of sternebrse 8 or 9. The variation is due to the presence or 

 absence of a short and nearly cubical piece between the xiphisternum and the sixth con- 

 stant mesosterneber. This piece is neither figured nor described by Mivart (B, Fig. 24), 

 or Parker (A, PI. xxx. Fig. 3), and does not appear distinctly in the figures of Straus- 

 Durckheim (A, PI. vi. Fig. 3, and PI. vii. Fig. 2), notwithstanding his intimation (A, 1,546) 

 that it is always present. In the sterna examined by us this seventh piece is sometimes 

 quite large, and in other cases so small as to be unrecognizable, at least from the surface. 

 We have also observed considerable diversity as to the number of costicartilagines which 

 reach the sternum, but are not yet prepared to say whether 8 or 9 is the more frequent 



