640 A MANUAL OF ANATOMY. 



collateral digital branches ; the external plantar furnishes 

 the remainder, two digital and three collateral digital 

 nerves. These are numbered from within outward. 



The Internal Plantar Artery. Figs. 133, 134. 



The smaller branch of the posterior tibial behind the 

 internal malleolus. Its course is forward and slightly out- 

 ward, under cover of the abductor hallucis muscle, then 

 between this muscle and the flexor brevis digitorum, to the 

 ball of the great toe where it terminates in branches which 

 anastomose with the fifth and sixth plantar digital arteries. 



The Branches of the Internal Plantar Artery. 



(i) Muscular, to the adjacent muscles. (2) Cutaneous, 

 to the integument of the inner segment of the sole. (3) 

 Anastomotic, beneath the abductor hallucis to the inner 

 side of the foot to anastomose with the internal malleolar 

 and internal tarsal arteries of the dorsum of the foot. (4) 

 Superficial digital, small branches which pass forward in 

 the inner three interosseous spaces with the digital branches 

 of the internal plantar nerve, and anastomose with the 

 digital arteries. 



DISSECTION. 



Section the internal plantar nerve where it appears in the sole. Divide the 

 abductor muscles about one inch in front of their origin, and the flexor brevis 

 digitorum transversely across at its middle. 



Reflect the parts. 



The Second Layer. 



Plexor Accessorius. Fig. 133. 



Origin. The internal, larger, head, from the inner sur- 

 face of the os calcis. The external, smaller, head from 

 the outer margin of the os calcis in front of the external 

 tuberosity, and from the long plantar ligament. 



