THE FOOT. 



THE FOOT. 



The foot is intended for support and locomotion. The locomotion takes place in 

 the upright position and, in moving, the weight is shifted from one foot to the other. 

 Hence we see that if the foot is to fulfil its function of support it must have strength, 

 because on it rests the weight of almost the whole of the body. If a person is at rest 

 in a standing position the foot is subject to a continuous static pressure which, if any 

 part of the foot is abnormal, whether from congenital or acquired qualities, will event- 

 ually result in distortion and impairment of function. If a person is moving about, 

 the foot is subjected to a pressure which is dynamic (movable) in character, and is 

 much greater in amount than is the static pressure of the body at rest. 



The movements of the foot in locomotion are not always slow, sometimes they 

 are exceedingly rapid. A person treads on an uneven or unstable surface and the 

 foot must adapt itself instantly or injuries will result; failure to do so results in sprains, 

 fractures, and luxations. In running rapidly the changes in position of the com- 

 ponent parts of the foot are instantaneous, otherwise rapid running is impossible. In 

 jumping especially the dynamic pressure plus the inertia causes an enormous strain 

 on the foot. The mobility demanded of the foot is not so great, however, as that of 

 the hand because the movements are neither so intricate nor so numerous. A con- 

 sideration of these facts enables one to understand: first, the method of construction 

 of the foot; second, its injuries, diseases and deformities; third, the means necessary 

 to employ in preventing and curing 

 them and in obviating to as great 

 extent as possible their consequences. 



The Construction of the 

 Foot. The foot is constructed with 

 a view of possessing strength and 

 mobility. Strength is obtained by 

 the bones being short and solid, well 

 compacted together in the form of a 

 double arch, joined by strong liga- 

 ments, and supported by powerful 

 muscles. The double arch forms the 

 hollow of the sole of the foot. As 

 pointed out by Ellis ("The Human 

 Foot " ) when the two feet are placed 

 together there is formed a " dome-shaped space " arching anteroposteriorly from the 

 internal tuberosity of the calcaneum to the head of the first metatarsal bone, and 

 laterally from the inner to the outer edge (Fig. 577). Mobility is obtained by the 

 bones and joints being numerous and the muscles highly specialized. 



Diseases and Injuries of the Foot. Disease weakens the foot sometimes, 

 as in adolescents, the foot is weakened without any apparent disease. In other cases 

 the bones and ligaments become affected, as in rickets, rheumatism, gout, and tuber- 

 culous disease. In still others the muscles become affected, either contracted, as in 

 spastic diseases, or relaxed, as in infantile paralysis. When the bones and ligaments 

 are involved they fail to bear the body weight, the arch is crushed and flat-foot and 

 eversion results. Hence valgus is almost always a disease of weakness. If muscles 

 become affected by spasm or paralysis all kinds of deformities are produced. There 

 are many muscles controlling the foot and frequently only one or a few are paralyzed; 

 this leaves the balancing muscles unopposed and they drag the part toward the 

 healthy side. Anything that disturbs the equilibrium or balance of the various 

 muscles results in distortions and deformities. Injuries impair the efficacy of the 

 mechanism of the foot. A crush of the head of the first metacarpal bone destroys 

 the anterior support of the arch and the resultant weakness is marked. 



Traumatism produces flat-foot, also sprains, which, while not so deforming, are 

 often disabling. Fractures and luxations occur and may impair the foot permanently. 



Finally, many children have congenitally deformed feet which require treatment 

 before they can fulfil their functions. 



36 



Inferior calcaneo-scaphoid ligament. 

 FIG. 577. Section of foot, showing the longitudinal arch. 



