472 THE INFERIOR EXTREMITY 



distal border of the popliteus, and at once passes forwards 

 through the proximal part of the interosseous membrane. Its 

 course corresponds to a line drawn from a point i inches lateral 

 to the tuberosity of the tibia to a second point, situated midway 

 between the two malleoli. In ligature of the vessel, the incision 

 is made along this line, and, after the deep fascia has been 

 divided, the tibialis anterior is retracted medially, and the other 

 muscles laterally. The artery is then exposed lying on the 

 interosseous membrane with the deep peroneal nerve either on 

 its lateral (proximal third) or anterior aspect (middle third). 

 In the distal third of the leg the artery lies on the tibia, and is 

 crossed obliquely by the tendon of the extensor hallucis longus. 

 The deep peroneal nerve again lies to its lateral side. 



After ligature of the anterior tibial artery, the circulation 

 is re-established through the anastomosis around the lateral 

 malleolus (p. 482) and the connection between the dorsalis pedis 

 artery and the plantar arch. 



The Deep Peroneal (Anterior Tibial) Nerve (L. 4, 5, and 

 S. i) arises from the common peroneal (external popliteal) on 

 the lateral aspect of the fibular neck and descends through the 

 anterior compartment of the leg in close relation to the anterior 

 tibial artery. It supplies all the muscles in the anterior 

 compartment and ends in front of the ankle-joint, by dividing 

 into lateral and medial branches. 



The lateral branch supplies the extensor digitorum brevis 

 and the neighbouring articulations ; the medial branch supplies 

 the dorsal aspects of the adjacent borders of the first and second 

 toes. 



The Dorsalis Pedis Artery is the direct continuation of 

 the anterior tibial. It commences midway between the two 

 malleoli and runs forwards over the talus, navicular, and second 

 cuneiform bones. At the posterior end of the first inter- 

 metatarsal space it passes downwards into the sole of the foot 

 and joins the plantar arterial arch, thus establishing an 

 important communication between the anterior and posterior 

 tibial arteries. It is placed very superficially, and its pulsations 

 can readily be felt on the lateral side of the flexor hallucis longus 

 tendon. 



When the anterior tibial is a small vessel, the dorsalis pedis 

 may be derived from the perforating branch of the peroneal 

 artery. 



The Superficial Peroneal (Musculo-Cutaneous) Nerve 



