504 A MANUAL OF ANATOMY 



external malleolus and outer border of the foot which communicate 

 with the terminal part of the short saphenous nerve. 



Summary of the Distribution of the Musculo-cutaneous Nerve. — The nerve 

 is distributed to the peroneus longus, peroneus brevis, integument over the 

 front of the leg in its lower tliird, integument of the malleolar regions and 

 outer and inner borders of the foot, and the integument of (i) the inner side 

 of the great toe, and (2) the contiguous sides of the second and third, third 

 and fourth, and fourth and fifth toes, all on their dorsal aspects. The dorsal 

 digital nerve of the outer side of the fifth toe is the terminal part of the short 

 saphenous nerve. 



The dorsal collateral digital nerves for the supply of the contiguous sides 

 of the great toe and second toe are derived from the dorsalis pedis nerve, 

 which is the continuation of the anterior tibial nerve. 



Muscles. Tibialis Anticus— Ongw.— (i) The external tuberosity of 

 the tibia at its lower part ; (2) the upper two-thirds of the external 

 surface of the shaft of the tibia and adjacent portion of the anterior 

 surface of the interosseous membrane ; and (3) the deep fascia, and 

 the anterior intermuscular septum which lies between it and the 

 extensor longus digitorum in the upper third of the leg. 



Insertion. — ^The tendon, having traversed the groove on the inner 

 surface of the internal cuneiform bone, divides into two slips. The 

 posterior slip is inserted into an oval impression at the lower part 

 of the inner surface of the internal cuneiform bone, and the 

 anterior slip is inserted into the inner surface of the tuberosity on 

 the plantar aspect of the base of the first metatarsal bone. 



Nerve-supply. — The anterior tibial nerve. 



Action. — (i) To flex the foot upon the leg, and (2) to raise the 

 inner border of the foot, thereby inverting the sole. 



Extensor Proprius or Longus Hallucis— Ongm. — The middle two- 

 four ihs of the anterior surface of the shaft of the fibula, and the 

 adjacent portion of the anterior surface of the interosseous mem- 

 brane. 



Insertion. — ^The dorsal surface of the base of the distal phalanx 

 of the great toe. 



Nerve-supply. — ^The anterior tibial nerve. 



Action. — (i) To extend the distal phalanx of the great toe, and 

 (2) to flex the foot upon the leg. 



The extensor proprius hallucis is a very narrow muscle which lies 

 deeply between the tibialis anticus and extensor longus digitorum, 

 both of which conceal it until its tendon appears on the fiont of the 

 lower part of the tibia. 



Extensor Longus Digitorum. — Origin. — (i) The external tuber- 

 osity of the tibia ; (2) the head and upper three-fourths of the 

 anterior surface of the shaft of the fibula ; (3) the anterior surface 

 of the interosseous membrane in its upper fourth ; (4) the inter- 

 muscular septa between it and adjacent muscles ; and (5) the deej) 

 fascia. 



Insertion. — ^The second and distal phalanges of the four outer toes. 

 The four tendons pass to the dorsal aspects of the metatarso- 

 phalangeal joints of the four outer toes. At this point they broaden 



