FLAT FOOT. 151 



tendons, those of the flexor longus digitorum and the flexor 

 longus hallucis aid in supporting the arch. 



The next factor is constituted by certain of the short muscles 

 of the sole of the foot, especially the abductor hallucis on the 

 inner side and the flexor brevis digitorum in the middle. After 

 this the strong plantar fascia bears its share in the support ; and 

 lastly, the skin also takes a part. 



To recapitulate the factors which maintain the longitudinal 

 arch, they are : the bones, certain ligaments, the tendons of 

 some of the long muscles of the leg, certain short muscles of the 

 sole of the foot, the plantar fascia and the skin. (Fig. 8.) 



The pain felt in many cases of flat-foot is mostly due to the 

 pressure exerted on the nerve-terminations in the ligaments 

 which are subjected to stretching, it being a well-known fact 

 that although ligaments and tendons may be cleanly divided 

 with but little discomfort, yet longitudinal tension of the same 

 leads to severe pain. When the bones constituting the longi- 

 tudinal arch have become so displaced as to no longer cause 

 tension of the ligaments, rigidity results and pain subsides 

 almost entirely. 



In flat-foot an extra bony point becomes prominent on the 

 inner side of the sole of the foot. Normally the internal 

 malleolus, the tuberosity of the navicular, and the base and head 

 of the first metatarsal are the bony points readily discernible. 

 When the arch is lost the head of the astragalus forces its way 

 into prominence between the internal malleolus and the tuberosity 

 of the navicular, the front of the foot being abducted and, as it 

 were, partially dislocated outwards at the astragalo-navicular 

 articulation. 



The transverse arch is most marked at the line of the tarso- 

 metatarsal joints, and is chiefly caused by the wedge shape of 

 the three cuneiform bones and of the bases of the metatarsals. 

 The tendon of the peroneus longus, and possibly the adductor 

 obliquus hallucis and the transversus pedis (adductor transversus 

 hallucis) muscles help to maintain the transverse arch. 



Congenital Talipes Equino-varus. Equino-varus is the most 



