THE PHALANGES. BONES OF THE FOOT AS A WHOLE. 



135 



is oblong or oval, and articulates with the cuboid ; on the inner side is generally a 

 double facet for the third metatarsal and the external cuneiform bones, but the arti- 

 culation with the latter is sometimes absent ; and on the outer side is a single surface 

 for the fifth metatarsal bone, with a deep groove below it. The fifth articulates by 

 its base with the cuboid, and internally with the fourth metatarsal bone, while 

 externally it projects in a large rough tuberosity, into which the peroneus brevis 

 muscle is inserted. 



Variety. In some rare cases an independent ossicle has been found taking 1 the place of 

 the tuberosity of the fifth metatarsal bone (W. Gruber, Virchow's Archiv, xcix, 460 ; Ch. 

 Debierre, Bull. Soc. Anat. de Paris, 1888, 392). 



THE PHALANGES. 



The phalanges of the toes correspond so nearly in general conformation 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 pha- 

 langes of the hand ; but those of the great toe are larger than those of the thumb. 

 The shafts of the first row of phalanges in the four outer toes are 

 compressed laterally and narrowed in the middle ; those of the 

 second row, more especially in the fourth and fifth toes, are very 

 short, their length scarcely exceeding their breadth. The last two 

 phalanges of the little toe are frequently connected by bone into 

 one piece. 1 



SESAMOID BONES. Two sesamoid bones, developed in the 

 tendons of the flexor brevis hallucis, 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 OP 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 extremity 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 from behind forwards, the posterior pier of the arch being 

 formed by the heel, the anterior by the heads of the metatarsal bones. The arch, 

 indeed, may be considered as double in front, with a common support behind. The 

 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 posterior two-thirds 

 of the calcaneum, the navicular and cuneiform bones, and the three inner metatarsal 

 bones ; the outer arch is formed by the calcaneum in its whole length, the cuboid 

 bone, and the fourth and fifth metatarsal bones. Besides being arched longitudinally, 

 the foot presents likewise a transverse arch, formed behind by the cuboid and three 

 cuneiform bones, and in front by the metatarsal bones. 



Fig. 156. PHA- 

 LANGES OF SECOND 

 TOE : PLANTAR 



ASPECT. (G.D.T.) 



1 W. Pfitzner found this union in about 36 per cent., and as frequently in infants as in adults 

 (Arch. f. Anat., 1890, 12). 



