THE PHALAXGES. 117 



nected with only three bones, its facet for articulation with the external 

 cuneiform being absent. The tarsal extremity of the first metatarsal 

 bone presents a slightly concave articular surface, and is broad belovr 

 . and narrow above. That of the fifth presents externally a large rough 

 tuberosity which projects beyond the other bones at the outer side of 

 the foot ; and the line of its articulation with the cuboid bone is so 

 oblique that, if prolonged inwards, it would reach the digital end of 

 the first metatarsal bone. The tarsal ends of the remaining three bones 

 are broad and flat above, rough and narrower below, and by their wedge- 

 like form assist in producing the transverse arch of the foot. 



The shafts present in the greater part of their extent a prominent 

 border looking upwards, which in the middle three projects between 

 the dorsal interosseous muscles on each side. 



The heads, or distal ends are smaller than the proxunal, and are 

 marked on their sides by depressions and tubercles. Their articular sur- 

 faces, smooth and convex, are prolonged on the inferior aspect, where 

 they terminate in bifid margins. That of the first metatarsal bone pre- 

 sents inferiorly a ridge in the middle, with grooved depressions placed 

 one on each side and corresponding to the position of the sesamoid bones. 



a?HE PHAIiANGES. 



The phalanges of the toes correspond so nearly in general conforma- 

 tion with those of the fingers that it will only be necessary in this place 

 to state the points in which they differ from the latter. 



The phalanges of the four outer toes are much smaller than the 

 corresponding phalanges of the hand ; but those of the gi-eat toe are 

 larger than those of the thumb. The shafts of the first row of pha- 

 langes in the four outer toes are compressed laterally and narrowed 

 in the middle ; those of the second row, more especially the fourth and 

 fifth, are very short, and consist of little beyond what is necessary to 

 unite their articular extremities. The last two phalanges of the little 

 toe are in adults not unfre quently connected by bone into one piece. 



Sesamoid Bones. — Two sesamoid bones lie side by side in the 

 plantar wall of the first metatarso-phalangeal joint, and glide in the 

 grooves on the head of the first metatarsal bone. Small sesamoid 

 bones sometimes occur in the corresponding joints of the other toes. 



THE BONES OF THE FOOT AS A WHOLE. 



The foot is narrowest at the heel, and as it passes forwards becomes 

 broader as far as the heads of the metatarsal bones. The posterior ex- 

 tremity of the calcaneum is inclined slightly inwards. The astragalus, 

 overhanging the sustentaculum tali, inclines inwards from the calcaneum 

 so much that its external superior border is directly over the middle 

 line of the calcaneum, and hence the internal malleolus appears more 

 prominent than the external. The foot is arched ft'om behind forwards, 

 the posterior pier of the arch being formed by the heel, the anterior 

 by the balls of the toes. The arch, indeed, may be considered as 

 double in front, with a common support behind. Th e internal division 

 of the arch is that which bears the greater part of the weight of the 

 body, and is most raised from the ground ; it consists of the calcaneum 

 in its posterior two-thirds, the scaphoid and cuneiform bones, and the 

 three inner toes ; the outer arch is formed by the calcaneum in its 



