162 ANATOMICAL TECHNOhOGT. 



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



The clamde or collar bone is briefly described in § 212. 



References.— Straus-Durckheim, A, I, 509 ; Flower, A, 228; Gegenbaur (Lankester), 

 A, 477 ; Gegenbaur, C ; Gray, A, 215-318 ; Quain, A, I, 84, 96 ; Parker, A, 315 ; Hum- 

 phrey, A, 359-863. 



§ 423. 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 



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



___Si>nster ^^^^^^fl^^ caudal diameter is nearly uniform, and that 



LaferaL '**^ ^^^^'^^toL ^^"^ ^""^ curves slightly caudad, the mesal 



_, ,„ ^ _, T y-i end the more decidedly. 



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



_ _ H The nerht is so placed as to show the 



VIOULiE OF AN OLD CAT: X 1. , , ^ :, -,. i ^i j ■, 



caudal aspect, and display the dor.sal 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. davo-trapezius, clavo- 

 mastoideus and davo-deltoideus, 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 (Fig. 7, 30, 50, 72, 73, 99, 100). 



The sternum or breast bone was briefly described in § 310. 



References. — Straus-Durckheim, A, 1, 496, 497 ; Mivart, B, 49, 50 ; Flower, A, 73 : 

 Humphrey, A, 331-339 ; Gray, A, 207-210 ; Quain, A, 1, 35-37 ; Chauveau, A, 75; Chau- 

 veau (Fleming), A, 66 ; Leyh, A, 164r-166 ; Parker, A, 315. 



§ 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 sternebrcE, united by ca/rtUages. 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, 

 prmsternum and npMsternum. The intervening segments constitute the mesosternum. 



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

 making the total number of stemebrse 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 meaosterneber. This piece is neither figured nor described by Mivart (B, Fig. 34), 

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

 Durckheim (A, PI. vi. Fig. 3, and PI. vii. Fig. 3), 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 



