624 



THE BLOOD-VASCULAR SYSTEM 



popliteal ligament, directly into the knee-joint, where it supplies the crucial ligaments, and the 

 patellar synovial and alar folds. It anastomoses with the intrinsic branches of the other articu- 

 lar arteries. 



(3) The terminal branches of the popliteal are the posterior and the anterior 

 tibial arteries. 



Fig. 499. — The Anastomosis about the Left Knee-joint. (Walsham.) 

 (Semi-diagrammatic.) 



Deep branch of genu suprema 

 Superficial branch of genu suprema 



Adductor magnus 



Superior medial articular artery 

 piercing tendon of adductor 

 magnus 



Tibial collateral ligament 



Inferior medial articular artery 

 passing under tibial collateral 

 ligament 



Posterior tibial artery 



Descending branch of lateral 

 circumflex artery 



Superior lateral articular artery 

 passing through external inter- 

 muscular septum 



Lateral epicondyle 



— Fibular collateral ligament 



Inferior lateral articular artery 

 passing under fibular collateral 

 ligament 



Anterior tibial recurrent artery 



Anterior tibial artery 



THE POSTERIOR TIBIAL ARTERY 



The posterior tibial artery [a, tibialis posterior] (fig. 500), the larger of the 

 two branches into which the popliteal divides at the lower border of the popliteus 

 muscle, runs downward on the flexor aspect of the leg between the superficial 

 and deep muscles to the back of the medial malleolus. Midway between the tip 

 of the malleolus and the calcaneus, and under cover of the origin of the abductor 

 hallucis as it arises from the laciniate (internal annular) ligament, it divides into 

 the medial and lateral plantar arteries. 



The artery is first situated midway between the tibia and fibula, and is deeply 

 placed beneath the muscles of the calf. As it passes downward it inclines to the 

 medial side and at the lower third of the leg is superficial, being only covered by 

 the skin and fascise. At the ankle it lies beneath the laciniate ligament, and at its 

 bifurcation also beneath the abductor hallucis. A line drawn from the centre of 

 the popliteal space to a spot midway between the medial malleolus and point of 

 the heel will indicate its course. In addition to the branches named below it 

 supplies the muscles between which it passes, and the integument of the lower 

 medial region of the leg. 



Relations. — Anteriorly, from above downward, it lies successively on the tibialis posterior, 

 the flexor digitorum longus, the posterior surface of the tibia, and the deltoid ligament of the 

 ankle-joint. 



Posteriorly, it is covered by the skin and fascia, the gastrocnemius and soleus, and the deep 

 or intermuscular fascia of the leg, by which it is tightly bound down to the underlying muscles. 

 It is crossed by the tibial nerve about 4 cm. (I4 in.) below its origin, after it has given off its 



