668 HUMAN ANATOMY. 



the extensor longus digitorum and the peronei. The muscles that draw up the heel, 

 — the gastrocnemius and soleus, — the muscles that elevate the inner border of the 

 foot and adduct it, — the tibalis anticus and posticus and the fiexor longus digitorum, 

 — are not resisted ; or, if the case is congenital, are assisted by the position of the 

 foot, which is therefore found with (a) the heel elevated ; (d) the innci- edge of the 

 sole drawn upward ; {c) its axis turned inward ; (^d) the sole shortened, partly- 

 through contraction of the plantar fascia. 



In marked cases the calcaneum will be almost vertical, as will the astragalus, 

 which will also be rotated forward so that its head may have two articular facets, one 

 of them projecting on the dorsum; the scaphoid is atrophied and is close to the 

 inner malleolus; the cuneiform bones accompany it, and the cuboid becomes the 

 chief point of support of the weight of the body. 



Corresponding changes occur in the metatarsal bones and phalanges, which may 

 be at right angles to the line of the inner side of the leg. 



Pure talipes varus, in which the elevation of the heel is absent, is very rare. The 

 other varieties of club-foot are seldom congenital. 



2. Talipes Valgus. — The foot is abducted and the outer border elevated by the 

 peronei, the inner side being correspondingly depressed and the arch of the foot 

 flattened out. 



3. Talipes Eqidniis. — The heel is drawn up by the gastrocnemius and soleus ; 

 the patient walks on the balls of the toes ; the os calcis and the astragalus are 

 changed in position as in equino-varus. The astragalo-scaphoid and calcaneo- 

 cuboid joints are much flexed, so that the scaphoid may even be in contact with the 

 OS calcis. 



4. Talipes Calcaneus. — The extensor longus digitorum and the extensor pro- 

 prius pollicis raise the toes and with them the foot, so that the anterior portion of the 

 OS calcis is elevated and the astragalus is rotated backward until its articular sur- 

 face points in that direction. The patient walks on the heel. 



Flat-foot results from weakness or relaxation of plantar muscles, fasciae, and 

 ligaments, especially the inferior calcaneo -scaphoid (page 445). When, in persons 

 who stand much of their time, or in those with defective ankles originally, this liga- 

 ment yields, the head of the astragalus is carried downward and inward by the body 

 weight, which, owing to the width of the pelvis, the obliquity of the femur, and the 

 curve of the tibia, is transmitted to the astragalus somewhat from without inward. 

 This is associated with abduction of the foot, resisted by the internal lateral and 

 calcaneo-astragaloid ligaments. This sinking of the astragalus and increased promi- 

 nence of the internal malleolus may be seen in many normal feet when the weight of 

 the body is thrown on one foot (page 449). In well-marked cases of flat-foot the 

 tibialis posticus fails to resist this change effectually, the peronei add to the abduction 

 or shortening, the arch of the sole of the foot entirely disappears or may even become 

 a rounded downward curve, the deltoid ligament stretches, as do the long and short 

 plantar ligaments, and the head of the astragalus, the scaphoid tubercle, and the 

 sustentaculum tali (page 449) become unduly prominent and may be the main points 

 of support. 



Two bursa about the foot are of enough importance to demand attention. 



The retrocalcaneal bursa lies between the os calcis and the tendo Achillis, the 

 depressions at the sides of which are effaced when the bursa is distended. The cor- 

 responding obliteration of the anterior depressions just beneath the malleoli (page 

 451), which occurs in ankle-joint disease, does not take place. Flexion or extension 

 of the foot or contraction of the calf muscles is painful. 



Bunio7is.—'\\\^x& may be normally a bursa over the metatarso-phalangeal joint 

 of the great toe, or an "adventitious" bursa — formed by dilatation of lymph-spaces, 

 condensation of connective tissue, and localized efTusion — may develop there, as a 

 result of pressure and friction from badly fitting shoes. The great toe is forced out- 

 ward, the internal lateral ligament of the articulation is elongated, the joint is made 

 unduly prominent, the head of the first metatarsal bone sometimes enlarges, and the 

 cartilage over its inner surface not uncommonly atrophies and disappears, leaving a 

 communication between the bursal sac and the synovial cavity of the joint. Flat- 

 foot and all degrees of valgus tend to produce a similar condition by exposing the 



• 



