PARTS OF THE HEART. 327 



§ 858. Arteria subclavia, A. sbclv. sin. — The subclavian ar- 

 tery (Fig. 91, 92, 101, 102, 108). — This arises from the arci^* aorticus 

 just peripherad of the A. bracTilo-cephalica. On Fig. 92 the abbre- 

 viation sin. is omitted. 



§ 859. Auricula dextra, aur. dxt.—HliQ right or pulmonary 

 auricle (Fig. 91, 92, 93, 94, 95, 99, 100).— The cavity of the auricle 

 is divisible into a larger sinus, dorsal in position and smoother 

 walled, and a smaller appendix, more ventral in position and with 

 corrugations and recesses upon the ental aspect of the wall. Into 

 the right auricle venous blood is poured tlirough the postcaDa, 

 prcecava and the VV. cardiacce. 



§ 860. Auricula sinistra, aur. sin. — The left or pulmonary, auri- 

 cle (Fig. 91, 92, 93, 95, 96, 99, 100).— Like the right, the left auricle 

 presents a sinus and an appendix. Purified blood is brought to 

 it by the YY. puhnonales. 



§ 861. Basis. — The base of either ventricle or of the entire ven- 

 tricular portion of the heart. 



§ 862. Capillariae pulmonales — The capillaries of the lungs. — 

 In Fig. 92, these are diagrammatically represented by three subdi- 

 visions of the single A. pulmonalis. In reality they are exceedingly 

 numerous and minute. 



§ 863. Capillarise systemicae — The systemic capillaries. — The 

 exceedingly numerous and minute subdivisions of the branches of 

 the aorta are represented in Fig. 91 by three. 



§ 864. Chordae tendineae, chd. tnd. — The tendinous cords con- 

 nected with the free borders of the auriculo-mntr icular valves on 

 both sides (Fig. 92, 93, 94 A). — These cords are very strong and 

 inelastic. Tlieir other ends are connected with the apices of the 

 coluvmcB carnece, and they serve to prevent the free borders of the 

 bicuspid and tricuspid valves from being forced back into the auri- 

 cles at the time of the ventricular systole. 



§ 865. Columnse carneae, elm. car. — The fleshy columns of the 

 ventricles (Fig. 91, 93, 94, 97, 98). — There are two large columns 

 in the left ventricle and a variable number of smaller ones in the 

 right. Consisting of muscle like the ventricular walls themselves, 

 these columns are supposed to contract and thus keep the cJiordcB 

 tendinece from becoming lax at the ventricular systole. 



§ 866. Conus arteriosus {dxt.\ con. ar^.— The arterial cone or 

 bulb from which springs the A. pulmonalis (Fig. 91, 92, 94, 100). — 



