181 



DISSECTION OF THE LEG. 



Metatarsal, 



outer border of the foot, where it divides into twigs that inosculate 

 with the metatarsal, external plantar, and anterior peroneal arteries : 

 it supplies offsets to the extensor muscle beneath which it lies. 



6. The metatarsal branch (fig. 70) takes an arched course to the 

 outer side of the foot, near the base of the metatarsal bones and 

 beneath the short extensor muscle, and anastomoses with the 

 external plantar and tarsal arteries. 



From the arch of the metatarsal branch three dorsal inter osseous 

 which gives arteries are furnished to the three outer metatarsal spaces : and the 

 external of these sends a branch to the outer side of the little toe. 

 They supply the interosseous muscles, and divide at the cleft of the 

 toes into two small dorsal digital branches. 



At the fore part of the metatarsal space each interosseous branch 

 is usually connected with the corresponding digital artery in the 

 sole of the foot by means of the anterior perforating twig ; and at the 

 back part of each space a small branch, posterior perforating, comes 

 from the plantar arch. 



c. The first dorsal interosseous artery arises from the main trunk 

 as this is about to leave the dorsuni of the foot ; it extends forwards 

 in the space between the first two toes, and is distributed like the 

 other dorsal interosseous offsets. 



The ANTERIOR TIBIAL VEINS have the same extent and relations 

 as the vessel they accompany. They take their usual position 

 along the artery, one on each side, and form loops around it by 

 cross branches ; they end in the popliteal vein. The branches 

 they receive correspond with those of the artery ; and they com- 

 municate with the internal saphenous vein. 



Dissection. To examine the extensor brevis digitorum on the 

 dorsuin of the foot, cut through the tendons of the extensor longus 

 and peroneus tertius below the annular ligament, and throw them 

 towards the toes. The hinder attachment of the muscle to the os 

 calcis is to be defined. 



The EXTENSOR BREVIS DiGiTORDM arises from the anterior 

 extremity of the os calcis at its upper and outer part, and from the 

 lower band of the anterior annular ligament. Over the metatarsal 

 bones the muscle ends in four tendons, which spring from as many 

 fleshy bellies, and are inserted into the four inner toes. The tendon 

 of the great toe has a distinct attachment to the base of the first 

 phalanx ; but the rest are united to the outer side of the long 

 extensor tendons, and assist to form the expansion on the first 

 phalanx (p. 180). 



The muscle lies on the tarsus, and is partly concealed by the 

 tendons of the long extensor. Its inner belly crosses the dorsal 

 artery of the foot, 

 use. Action. Assisting the long extensor, it straightens the four 



inner toes, separating them slightly from each other. 



Cut through Dissection. The branches of artery and nerve which are 

 breves 01 " beneath the extensor brevis will be laid bare by cutting across that 

 muscle near its front, and turning it upwards. 



By dividing the lower band of the annular ligament over the 



interos- 

 seous, 



and per- 

 forating. 



First inter- 

 osseous. 



Anterior 

 tibial veins. 



Divide 



extensor 



longus. 



Extensor 



brevis 



digitorum 



sends ten- 

 dons to four 

 inner toes : 



relations 



and annular 

 ligament : 



