58 LANDMARKS MEDICAL AND SURGICAL. 



the interdigital folds of the skin. This is a point to be 

 remembered in amputating the toes. 



126. Dorsal artery. The line of the dorsal artery of the 

 foot is from the middle of the ankle to the interval between 

 the first and second metatarsal bones. The artery can be 

 felt beating over the bones along the outer side of the ex- 

 tensor longus pollicis, which is the best guide to it. 



127. Bursa. The synovial sheath of the extensor longus 

 pollicis extends from the front of the ankle, over the instep 

 (apex of the internal cuneiform bone) as far as the metatarsal 

 bone of the great toe. There is generally a bursa over the 

 instep, above, or it may be, below, the tendon. 



There is often a large irregular bursa between the tendons 

 of the extensor longus digitorum, and the projecting end of 

 the astragalus, over which the tendons play. There is much 

 friction here. It is well to be aware that this bursa some- 

 times communicates with the joint of the head of the 

 astragalus. 



128. Plantar arteries. The course of the external plantar 

 artery corresponds with a line drawn from the hollow behind 

 the inner ankle obliquely across the sole nearly to the base of 

 the fifth metatarsal bone ; from thence the artery turns trans- 

 versely across the foot, lying (deeply) near the bases of the 

 metatarsal bones, till it inosculates with the dorsal artery of 

 the foot in the first interosseous space. 



The course of the internal plantar corresponds with a 

 line drawn from the inner side of the os calcis to the middle 

 of the great toe. 



129. Plantar fascia. To divide the plantar fascia sub- 

 cutaneously, the best place is about one inch in front of its 

 attachment to the os calcis. This is the narrowest part of it. 

 The knife should be introduced on the inner side ; and the 

 incision will be behind the plantar artery. 



The subcutaneous section of the tendon of the abductor 

 pollicis should be made about one inch before its insertion. 



