142 THE PULMONARY VESSELS. 



middle of the bone ; where proceeding obliquely, it gains the 

 centre of the thigh ; and is continued down behind that bone. 

 Pursuing its course, the femoral artery at length reaches 

 the sulcus at the back of the stifle ; to which last it 

 sends numerous small arteries, called the pophteals (Fig 

 15 . i). In its course the femoral dispatches the inguinal 

 {Fig 15 . e) ; which last proceeds to get between the vastus 

 internus and rectus ; giving off branches to all the parts 

 through which it passes. The femoral artery subsequently 

 sends blood to all parts of the thigh ; the twigs by means 

 of which it does so having no name ; and upon reach- 

 ing the stifle divides into the anterior {Fig 15 . j) and 

 posterior tibial {Fig \5 . k) arteries. The j^osterior tibial 

 artery is continued down the posterior of the tibia. The 

 anterior tibial {Fig 16 . c) forms the other division of the 

 femoral ; and runs obliquely to the external inferior part of 

 the tibia; passing between that bone and the fibula, the 

 artery then takes its course between the extensor muscles. 

 It here winds round the outer side of the hock ; and de- 

 scending along the cannon bone changes its name to the 

 metatarsal artery {Fig 16 . d) ; which is continued down 

 between the large and the small metacarpal bones. It thus 

 gains the superior part of the sessamoid bones; when it bifur- 

 cates into the two pastern or plantar arteries ; following a 

 similar distribution with those of the fore extremities. 



THE PULMONARY VESSELS. 



The pulmonary artery {Fig 13 . 2) unlike the generality of 

 similar tubes conveys venous blood from the right side of the 

 heart ; and the pulmonary veins carry arterial blood back to 

 the left auricle. This is their striking peculiarity or chief cha- 

 racteristic. The passage of the blood through these vessels 

 is termed the minor circulation. The pulmonary artery is a 

 trunk of five or six inches in length ; given ofl' from the right 

 ventricle of the heart : immediately after which it divides into 

 the right and left branches ; the right being more consider- 

 able than the left, in conformity with the additional lobe of 

 the right lung. Each of these branches is divided upon 

 its entering the lungs into others ; which being subdivided 

 ramify throughout the substance of the lungs. From the 

 minute distributions of the artery, the blood is received into 



