The Lower Extremity and Pelvis 



173 



All these varieties are represented in the supports of the longitudinal arches of the 

 foot. 



To deal first with the inner side, (i) The intersegment al ties are represented by 

 the ligaments connecting the articulating bones, and these must therefore be strong 

 on the concave or plantar side : no strain is thrown on them on the dorsal side. (2) Ties 

 between the pillars are provided by the muscles and fasciae extending between the 

 tuberosity of the os calcis and the great toe along the inner side of the foot. (3) The 

 expansion from the tendon of Tibialis posticus to cuboid, passing under the head of the 

 astragalus, acts as a strap under the highest part of the arch : observe (Fig. 142) that 

 this is not the direct tendon that goes to the scaphoid, for this can give no aid in 



FIG. 142. Schemes of the supporting structures in the foot, for com- 

 parison with the last figure, i, i, i, are ties between the seg- 

 ments ; 2, between the pillars ; 3, strap-like support passing 

 under the arches. In the low outer arch i and 2 are stronger. 



supporting the inner arch, but its expansion crosses under the arch to be attached 

 outside it. 



The outer arch is lower than the inner, and low arches are much harder to hold 

 up (Fig. 141) by intersegmental ties and ties between the pillars ; so we would expect 

 to find the ligaments on the plantar side of the outer arch much stronger than those 

 under the inner arch, and much stronger connections between the tuberosity of the 

 os calcis and the outer toes, whereas the strap passing under such an arch would not 

 be affected in its action, although more work would probably be thrown on it. And 

 this is what 'is found in the low external arch : the long and short plantar ligaments 

 connecting the os calcis, cuboid, and outer metatarsals are the strongest in the foot ; 

 the fascia is very thick and the muscles largely ligamentous along the outer side of 

 the sole, and the tendon of the Peroneus longus passes under the arch to be fastened 

 away from it, acting under the highest part arid being very strong. In this, then, we 

 find some explanation of the occurrence of such strong ligaments and ligamentous 

 " degeneration " of muscles in the outer moiety of the foot. 



