METACARPUS AND PHALANGES. 147 



The metacarpal lone of the little finger may be distinguished by the concavo- 

 convex form of its carpal surface, for articulation with the unciform, and from 

 having only one lateral articular facet, which corresponds with the fourth meta- 

 carpal bone. On its ulnar side, is a prominent tubercle for the insertion of the 

 tendon of the Extensor carpi ulnaris. The dorsal surface of the shaft is marked 

 by an oblique ridge, which extends from near the ulnar side of the upper extremity, 

 to the radial side of the lower. The outer division of this surface serves for the 

 attachment of the fourth Dorsal interosseous muscle ; the inner division is smooth, 

 and covered by the Extensor tendons of the little finger. 



Articulations. The first, with the trapezium ; the second, with the trapezium, 

 trapezoides, os magnum, and third metacarpal bones ; the third, with the os mag- 

 num, and second and fourth metacarpal bones ; the fourth, with the os magnum, 

 unciform, and third and fifth metacarpal bones ; and the fifth, with the unciform 

 and fourth metacarpal. 



Attachment of Muscles. To the metacarpal bone of the thumb, three : the Flexor 

 ossis metacarpi pollicis, Extensor ossis metacarpi pollicis, and first Dorsal inter- 

 osseous. To the second metacarpal bone, five : the Flexor carpi radialis, Extensor 

 carpi radialis longior, first and second Dorsal interosseous, and first Palmar inter- 

 osseous. To the third, five : the Extensor carpi radialis brevior, Flexor brevis 

 pollicis, Adductor pollicis, and second and third Dorsal interosseous. To the 

 fourth, three : the third and fourth Dorsal interosseous and second Palmar. To 

 the fifth, four: the Extensor carpi ulnaris, Flexor carpi ulnaris, Flexor ossis 

 metacarpi minimi digiti, and third Dorsal interosseous. 



PHALANGES. 



The Phalanges are the bones of the fingers ; they are fourteen in number, three 

 for each finger and two for the thumb. They are long bones, and present for 

 examination a shaft, and two extremities. The shaft tapers from above down- 

 wards, is convex posteriorly, concave in front from above downwards, flat from 

 side to side, and marked laterally by rough ridges, which give attachment to the 

 fibrous sheaths of the Flexor tendons. The metacarpal extremity or base, in the 

 first row, presents an oval concave articular surface, broader from side to side, 

 than from before backwards ; and the same extremity in the other two rows, a 

 double concavity separated by a longitudinal median ridge, extending from before 

 backwards. The digital extremities are smaller than the others, and terminate, 

 in the first and second row, in two small lateral condyles, separated by a slight 

 groove, the articular surface being prolonged farther forwards on the palmar than 

 on the dorsal surface, especially in the first row. 



The Ungual phalanges are convex on their dorsal, flat on their palmar surfaces; 

 they are recognized by their small size, and from their ungual extremity presenting, 

 on its palmar aspect, a roughened elevated surface of a horseshoe form, which 

 serves to support the sensitive pulp of the finger. 



Articulations. The first row with the metacarpal bones, and the second row of 

 phalanges ; the second row, with the first and third ; the third, with the second 

 row. 



Attachment of Muscles. To the base of the first phalanx of the thumb, four 

 muscles : the Extensor primi internodii pollicis, Flexor brevis pollicis, Abductor 

 pollicis, Adductor pollicis. To the second phalanx, two : the Flexor longus pollicis, 

 and the Extensor secundi internodii. To the base of the first phalanx of the 

 index finger, the first Dorsal and the first Palmar interosseous; to that of the middle 

 finger, the second and third Dorsal interosseous; to the ring finger, the fourth 

 Dorsal and the second Palmar interosseous ; and to that of the little finger, the 

 third Palmar interosseous, the Flexor brevis minimi digiti, and Abductor minimi 

 digiti. To the second phalanges, the Flexor sublimis digitorum, Extensor com- 

 munis digitorum ; and, in addition, the Extensor indicis, to the index finger ; the 

 Extensor minimi digiti, to the little finger. To the third phalanges,, the Flexor 

 profundus digitorum and Extensor communis digitorum. 



