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opposite or inner side of the base for the second metatarsal. The distal arti- 

 cular surface is a compound pulley similar to that on the third metacarpal ; 

 with the median ridge sharpest and most produced below, where it is wedged 

 into the interspace of the two large sesamoid bones. 



The proximal phalanx of the middle toe (1) is as wide as it is long, and nearly 

 twice as deep : the upper surface, which has a transversely quadrate form, pre- 

 sents a convex transverse rough bar above the proximal articulation, and a de- 

 pression in front of the bar. The outer side of this phalanx is nearly flat, the 

 inner side gibbous towards its lower end. The proximal articular surface is con- 

 cave, adapted to the upper two-thirds of the convex trochlea of the metatarsal 

 bone, and widening as it descends. The distal articular surface presents a vertical 

 concave channel, also widening as it descends, and almost meeting the proximal 

 surface at the middle of the under part of the phalanx, which is notched, with a 

 tubercle on each side. 



The proportions of the middle phalanx (2) differ much from those of the pre- 

 ceding bone : its antero-posterior diameter exceeds by one-eighth part the vertical 

 diameter, and by one-third part the transverse diameter. The depth of the pha- 

 lanx rapidly contracts from the proximal end ; the sides are flattened, and 

 shghtly concave in the middle : they terminate anteriorly in the convex borders 

 of the distal trochlea, which describe two-thirds of a circle ; the median depres- 

 sion of the pulley follows the same curve, and terminates both above and below 

 in a wide and deep cavity. The proximal articulation consists of two vertical 

 concavities separated by a median ridge ; the upper extremity of which is more 

 produced than the lower one ; but both combine to restrict the movements of the 

 middle upon the proximal phalanx in the vertical direction, in which alone any 

 motion is permitted by the form of the articular pulley. 



The greater length of the second phalanx, and the more extensive curve of its 

 distal trochlea, allows much freer motion to the ungual phalanx (3), which can be 

 made to describe a quarter of a circle in the direction to which its movements are 

 restricted. The position of the trochlear cavity, which extends obhquely from 

 above downwards and forwards over the base of the ungual phalanx, and the 

 backward production of the upper end of the median trochlear ridge, cause this 

 phalanx, in extreme extension, to have its long axis parallel with that of the 

 middle phalanx : in extreme flexion the point of the claw is bent down at right 

 angles to the middle phalanx. The lateral concavities receiving the trochlear con- 



q2 



