252 Prof. J. C. Galton on the Myology 



The extensor ossis metacarpi pollicis arises from the external 

 condyloid ridge, in company Avith the extensor communis digi- 

 torum and the extensor minimi digiti. It passes obliquely 

 (the hand being pronated) over the tendon of the extensor 

 carpi radialis, and is inserted by a strong tendon into the rudi- 

 ment of the pollex (or trapezium?). 



The extensor communis digitorum takes origin from the 

 external condyloid ridge of the humerus, immediately below 

 the extensor carpi radialis, but in company with the muscle 

 just described. At the carpal joint its tendon is closely bound 

 down by a strong ligament stretched between the distal end of 

 the radius and the dorsal surface of the cuneiform bone, and 

 terminates at the dorsal aspect of the base of the distal phalanx 

 of the third (" middle ") digit, being reinforced, close to its 

 termination, by a short extensor (dorsal interosseous, Cuv.) on 

 either side. 



The extensor brevis digitorum manus, a kind of accessory 

 extensor muscle, arose from the distal end of the dorsum of the 

 ulna, and from the dorsum of the os magnum and unciform 

 bone. The principal portion of the muscle passes to either 

 side of the tendon of the extensor communis, just short of its 

 termination at the nail of the third digit. A thin slip, given 

 off from the radial side of the muscle, and which also arises 

 from a ligament joining the scaphoid and lunar bones, is in- 

 serted by tendon into the base of the ungual phalanx of the 

 index. This muscle, to which the symbol of the dorsal inter- 

 osseus is appended in Cuvier's plates, answers to one which 

 Prof. Macalister describes [loc. cit. p. 62) as present in Bra- 

 dypus^ and which " seems," he says, "to contain the displaced 

 germs of the dorsal interossei." 



From the external condyle of the humerus, immediately 

 below and in company with the extensor minimi digiti, and 

 from the proximal two-thirds of the outer surface of the ulna, 

 arises a muscle which is inserted by tendon into the ossicle 

 (rudiment of fifth digit) which lies to the ulnar side of the 

 unciform bone and the rudiment of the fourth digit. This is 

 not improbably the extensor carpi ulnaris. 



A well-developed muscle takes origin from the external 

 condyloid ridge, in company with the extensor ossis metacarpi 

 pollicis and the extensor communis, and has a broad tendinous 

 insertion into the ulnar side of the base of the proximal pha- 

 lanx of the third digit. This may be a displaced extensor 

 annularis or extensor minimi digiti. 



The pronator teres, a muscle of uniform width, arises from 

 the ridge above the inner condyle, and is inserted by a flat 

 tendon into the distal end of the radius, being covered at its 



