THE LEG 355 



injected, or examined with a probe in the manner indicated 

 when the sheaths of the extensors were described (see p. 341). 



Dissection. After the mucous sheaths of the peronaei tendons 

 have been examined, the lateral compartment of the leg must 

 be opened up to display its contents. Divide the deep fascia 

 over the peronaei muscles by a longitudinal incision, and turn 

 the flaps aside until their continuity with the anterior and 

 posterior fibular septa is demonstrated, but do not injure the 

 peroneal retinacula. 



Enclosed within the lateral compartment of the leg are the 

 following structures: 



1. The peronasus longus. 



2. The peronseus brevis. 



3. The termination of the common peroneal nerve. 



4. The superficial peroneal nerve. 



M. Peronseus Longus. The peronseus longus muscle 

 arises from the head and from the lateral surface of the shaft 

 of the fibula in its proximal two-thirds. Surfaces of origin are 

 also afforded to it by the fascia which covers it, and by the 

 two fibular intermuscular septa. It ends, a short distance 

 proximal to the ankle, in a long tendon, which is continued 

 distally posterior to the lateral malleolus. Gaining the lateral 

 border of the foot, it proceeds forwards, on the lateral surface 

 of the calcaneus, to the groove on the plantar surface of the 

 cuboid, which conducts it obliquely into the sole. Its 

 insertion will be examined at a later period (see p. 400). It 

 is supplied by the superficial peroneal nerve (O.T. musculo- 

 cutaneous) and is a plantar flexor and evertor of the foot. 



M. Peronseus Brevis. The peronaeus brevis muscle arises 

 from the distal two-thirds of the lateral surface of the body 

 of the fibula, anterior and distal to the peronaeus longus, 

 and from the fibular intermuscular septum on each side 

 of it. Its tendon descends, posterior to the lateral malleolus, 

 and then turns forwards, on the lateral surface of the calcaneus, 

 to gain an insertion into the projecting base of the metatarsal 

 bone of the little toe. 1 



As the tendons of the two peronsei muscles proceed 

 distally, in the hollow between the lateral malleolus and the 

 posterior prominence of the calcaneus, they are held in place 

 by the superior peroneal retinaculum^ and their movements are 



1 A small tendinous slip will, sometimes, be observed to proceed forwards 

 from the tendon of the peronseus brevis to join the tendon of the long 

 extensor on the dorsum of the little toe. This is the peronceus digiti quinti. 

 I 23 a 



