188 ME. r. E. BEDDAKD — CONTEIBUTIONS TO THE 



(24) Extensor carpi radialis hrevior. — This muscle is larger than the last ; it rises, 

 in common with the other extensors, from the extensor condyle of the humerus ; it 

 does not become free from the extensor communis until a point four inches distant from 

 the humerus ; it becomes entirely tendinous about two inches further on ; the tendon is 

 quite twice the breadth of that of the last extensor ; it is inserted on to the base of the 

 metacarpal of the third digit. 



(25) Extensor communis digitorum. — This extensor is of course the largest of all; it 

 arises from the extensor condyle of the humerus, from the septa between itself and 

 adjacent muscles, and from the fascia covering the deep extensors ; it divides into four 

 separate muscles, which end in tendons at various distances from their insertion ; the 

 longest tendon is that supplying the third digit ; each tendon supplies one of the 

 digits ii.-v. ; it is inserted on the first and second phalanges, and spreads out into a 

 thin layer almost covering these bones. 



(26) Extensor minimi digiti appears to be totally absent, unless it is a part of extensor 

 communis that is absent ; the tendon of that division of the " communis " which 

 supplies digit v. is separated from the others at the wrist. 



(27) Extensor carpi ulnaris is the outermost of the extensors; its origin extends 

 down the arm to a point beyond the middle ; the tendon, which is very strong and 

 round rather than flat, is inserted on to the outer side of the base of the last 

 metacarpal. 



(28) Supinator radii hrevis. — This muscle is distinctly double as in the Orang ; the 

 posterior boundary is marked by the exit of the nerve ; the entire muscle is inserted 

 on to the radius for more than one third of its length ; the insertion of the deeper 

 layer extends nearly an inch below that of the upper layer. 



(29) Extensor ossis metacarpi pollicis. — The origin of this muscle is from the radius 

 and ulna, and from the interosseous ligament ; the muscle divides early, and the 

 two tendons pass down in close contact, and are inserted on to radial carpal and base of 

 metacarpal respectively. 



(30) Extensor secundi internodii pollicis. — This muscle arises from the inner side of 

 the ulna, from the interosseous membrane, and from the septa between itself and the 

 extensor indicis and other adjacent muscles ; its long tendon is inserted on to the second 

 phalanx of the thumb. 



(31) Extensor indicis. — This muscle is almost exactly the same size as the last, and 

 their origins are close together, being partly from the septum dividing them ; the 

 extensor indicis also arises from the upper surface of the ulna, below the origin of the 

 extensor carpi ulnaris; it is attached to the index only by a strong tendon which joins 

 that of the branch of the extensor communis supplying that digit. 



(32) Extensor primi internodii pollicis. — This muscle is superficial to the extensor 

 ossis metacarpi pollicis, from which, however, it is hardly separable ; it arises, with that 

 muscle, from the radius, from the interosseous membrane, and from the septa between 



