3 io ZOOTOMV. 



The apex of the heart is somewhat displaced towards the left of the 

 subject : the arteries of the right and the veins of the left side are in 

 great measure removed. 



a.ao, arch of the aorta : a.epg, internal mammary artery : a.f, anterior 

 facial vein : a.m, anterior niesenteric artery : a.ph, anterior phrenic 

 vein : az.v, azygos vein : br, brachial artery : cM.a, common iliac 

 artery : c.il.v, common iliac vein : c&, coeliac artery : d.ao, dorsal 

 aorfa : e.c, external carotid artery: .e.il.a, external iliac artery: e.il.v, 

 external iliac vein : e.jti, external jugular vein : Jin. a, femoral artery : 

 fm.v, femoral vein : h.v, hepatic veins : i.c, internal carotid artery : i.cs, 

 intercostal vessels: i.il.a, internal iliac artery: i.il.v, internal iliac 

 vein : i.ju, internal jugular vein : i.l, ilio-lumbar artery and vein : in, 

 innominate artery : l.au, left auricle : L-'.L, left common carotid artery : 

 l.prc, left precaval vein : /. z/, left ventricle : in.sc, median sacral artery : 

 p. a, pulmonary artery: p.epg, epigastric artery and vein : p.f, posterior 

 facial vein : p. in, posterior mesenteric artery : p.ph, posterior phrenic 

 veins : ptc, postcaval vein : p.v, pulmonary vein: r, renal artery and 

 vein : r.au, right auricle : r.c.c, right common carotid artery : r.prc, 

 right precaval vein : r. z>, right ventricle : scl.a, subclavian artery : scl.v, 

 subclavian vein : spin, spermatic artery and vein : s.vs, superior vesical 

 artery and vein : ut, uterine artery and vein : vr, vertebral artery. 



231. The two precaval veins, or venae cavse supe- 

 riores (r.prc, l.prc), passing from the anterior end of the 

 thorax towards the base of the heart : each is formed by 

 the union of the subclavian vein (scl.v), from the 

 corresponding arm, and the external jugular vein 

 (e.jii) already noticed ( 127) from the head ; the right pre- 

 caval is seen at once to enter the right auricle : the left 

 trunk is seen, on lifting up the heart, to curve round the 

 dorsal side of the base of that organ, and enter the same 

 chamber. Sometimes the two external jugular veins unite 

 with one another by a transverse connecting trunk in the 

 posterior region of the neck. 



The external jugular is constituted anteriorly by the anterior facial 

 vein (a.f), which runs just within the ramus of the mandible, and the 

 posterior facial vein, (/./), coining from the external ear ; near its junc- 

 tion with the subclavian, it receives the internal jugular vein (i.jtt), 

 which runs close alongside the trachea, and receives the blood from the 

 brain. 



