282 MUSCLES OF THE LOWER LIMB. 



Five tendons are ascribed to the extensor longus digitorum by Cowper (Myot. 

 Eeform., c. 36, p. Ill), the peroneus tertius having been considered by him as part of 

 that muscle, a view which is in some degree warranted by the form which it usually 

 presents. 



The extensor brevis digitorum pedis arises from the outer surface of the os 

 calcis in front of the groove for the peroneus brevis muscle, and from the 

 lower band of the anterior annular ligament. It divides into four tapering- 

 slips each of which terminates in a tendon ; the first or most internal of 

 these, sometimes reckoned as a distinct muscle, is inserted separately into 

 the dorsal surface of the first phalanx of the great toe near its tarsal 

 extremity ; and the other three become severally united to the outer border 

 of the extensor tendons proceeding to the three next toes. 



EXTERNAL REGION. 



The peroneus longus arises from the head of the fibula, and from more than 

 the two upper thirds of the external surface of that bone ; from the fascia 

 of the leg ; and from aponeuroses interposed between it and the contiguous 

 muscles, viz., the extensor communis digitorum on one side, and the soleus 

 and flexor longus pollicis on the other. It ends above the ankle in a 

 tendon, which passes downwards behind that of the peroneus brevis in the 

 hollow behind the external malleolus, and inclining forwards, turns over the 

 outer margin of the foot, and enters the excavation on the lower surface of 

 the cuboid bone, and changing its direction, proceeds inwards and forwards 

 to be inserted into the lower part of the internal cuneiform and the tarsal 

 end of the first metatarsal bone : an offset is continued from it to the base 

 of the second metatarsal bone. In this course the tendon of the peroneus 

 longus muscle, lying parallel with that of the peroneus brevis, is invested 

 along with it by a synovial membrane, and bound down by a fibrous band 

 extended from the end of the fibula to the calcaneum ; on the outer side of 

 the foot it separates from the peroneus brevis, and in the sole of the foot 

 the peroneus longus lies in a synovial sheath formed by fibres of the liga- 

 mentum longum plantte. 



The peroneus brevis arises from the two lower thirds of the external 

 surface of the fibula, internal to the peroneus longus, and from the inter- 

 muscular septa which dip down in front between it and the extensor longus 

 digitorum and peroneus tertins, and behind between it and the flexor longus 

 pollicis. The fibres are directed to a tendon on their outer surface, which 

 becoming free at the level of the external malleolus, passes behind that 

 process, sheathed in the same synovial membrane as the tendon of the 

 peroneus longus, and inclining forwards is inserted into the projection at the 

 base of the fifth metatarsal bone, having traversed a separate sheath on the 

 calcaneum, above that for the tendon of the peroueus longus, but lined by 

 an offset of the same synovial membrane. 



POSTERIOR REGION. 



The muscles at the back of the leg consist of a superficial group inserted 

 into the extremity of the calcaneum, and a deeper group covered in by a 

 deep fascia and descending to the sole. 



The superficial group consists of three muscles ; two of them, placed one 

 on the surface of the other, are of large size, the gastrocnemius and soleus 

 (extensor tarsi suralis vel extensor magnus, Douglas ; musculus surse, 



