496 THE ARTERIES OF THE LOWER LIMB. 



SURGICAL ANATOMY OF THE POPLITEAL ARTERY. 



The popliteal arteiy is very rarely tied, since, in cases of aneurism of the arteries of the 

 upper part of the leg, ligature of the superficial femoral artery is both an easier and a more 

 successful operation. The artery might, however, if necessary, be secured either in its upper 

 or its lower part, but in the middle portion of its extent, while contained within the popliteal 

 space, the artery is closely covered by the vein and nerve, as well as by the sural branches of 

 the vessels and the external saphenous vein ; and moreover the principal branches are also 

 arising here, so that a ligature cannot be safely applied to this part of the vessel. In its 

 upper part the artery may be reached either by making an incision on the inner side of the 

 thigh in its lower third, and then separating the sartorius and inner hamstring muscles from 

 the tendon of the adductor magnus, or by dividing the integument in the middle line of the 

 limb posteriorly, and then turning inwards the semimembranous muscle. In an operation 

 upon the lower part of the artery, the incision would have to be carried between the heads of 

 the gastrocnemius muscle, care being taken to avoid the external saphenous vein. 



POSTERIOR TIBIAL ARTERY (HI). 



The posterior tibial artery, the larger of the two vessels resulting from the bifur- 

 cation of the popliteal, lies along the back of the leg, between the superficial and 

 deep muscles of this part, being closely bound down to the latter group by the fascia 

 which covers them. It extends from the lower border of the popliteus muscle 

 to the lower border of the internal annular ligament, where it divides, on a level 

 with a line drawn from the point of the internal malleolus to the centre of the con- 

 vexity of the heel, into the internal and external plantar arteries. 



Situated at its origin opposite the interval between the tibia and fibula, the 

 artery approaches the inner side of the leg as it descends, and lies behind the tibia ; 

 at its lower end it is placed midway between the inner malleolus and the prominence 

 of the heel. Very deeply seated at the upper part, where it is covered by the fleshy 

 portions of the gastrocnemius and soleus muscles, it becomes superficial in the 

 lower third of the leg, being there covered only by the integument and two layers of 

 fascia, and by the annular ligament behind the inner malleolus. At its termination 

 the artery is placed beneath the origin of the abductor hallucis muscle. It lies 

 successively upon the tibialis posticus, the flexor longus digitorum, and, at its lower 

 end, directly on the tibia and the ankle-joint. Behind the ankle, the tendons of the 

 tibialis posticus and flexor longus digitorum lie between the artery and the internal 

 malleolus ; while the tendon of the flexor longus hallucis is to its outer side. 



Relation to the veins and nerve. The posterior tibial artery is accompanied by 

 two venm comites. The posterior tibial nerve is at first on the inner side of the 

 artery, but as soon as the latter has given off its peroneal branch, the nerve crosses 

 over the vessel and is continued down on its outer side. Beneath the internal 

 annular ligament the artery is frequently placed between the internal and external 

 plantar divisions of the posterior tibial nerve. 



BRANCHES. The posterior tibial artery gives off one large branch the peroneal 

 artery, and numerous small offsets which will be first described. 



1. Several muscular branches are distributed to the deep-seated muscles, and 

 one or two of considerable size to the inner part of the soleus muscle. A small 

 offset from one of these perforates the tibial attachment of the soleus, and ascends 

 over the popliteus muscle to anastomose with the lower internal articular arteiy. 



2. The medullary artery of the tibia, the largest of its kind in the body, 

 arises from the posterior tibial near its commencement, and, after giving small 

 branches to the neighbouring muscles, enters the foramen in the bone. This vessel 

 not unfrequently arises from the anterior tibial artery. 



3. Two or three cutaneous branches, of small size, supply the skin of the inner 

 side of the leg. 



4. A communicating branch passes transversely, beneath the flexor longu 



