1868.] ^Ix.^ .Woodi on Variations in Human Myology. 513 



from the intermuscular septum, between the extensor communis and ex- 

 tensor ossis metacarpi pollicis, forming a layer intermediately placed, and 

 appearing, at first sight, to be connected with the deep surface of the 

 common extensor. Its pollex-insertion was with the tendon of the secundi ; 

 and at its indicial it joined the outermost of the tendons of a double indi- 

 cator' to be inserted into the base of the first phalanx. This origin of the 

 muscle seems to form an intermediate link, and to connect it with the 

 somewhat similar abnormality of the extensor communis digitorum in 

 subject 27 (see fig. 7 a). 



35. Extensor medii digiti. — In 2 males (1 in the right arm, and the 

 other in the left), and in 4 females (2 in both arms, 1 in the right, and 1 

 in the left), this muscle was found arising in common with the indicator^ 

 the lower fibres of which gave off a tendon to be inserted into the base of 

 the first phalanx of the middle digit. In 2 females, in both arms, it was 

 found as a separate muscle arising, below the indicator, from the ulna and 

 interosseous ligament. In the right arm of one of them (No. 28) the 

 muscle had a peculiar origin from the intermuscular septum between the 

 extensor communis digitorum and supinator brevis, higher and more super- 

 ficial than the rest of the deep muscles. Forming a fusiform belly, it 

 ended in a long tendon, which was inserted into the extreme or ungual 

 phalanx of the middle finger, internal to the common extensor, crossing 

 the fibres of insertion of the interosseus. This abnormality, again, has a 

 resemblance to the variety of the extensor pollicis et indicis just described 

 in the male (No. 11). In both arms of No. 33 (the subject of fig. 8) 

 the muscle {b) was distinct and gave off two tendons, of which the inner 

 was inserted into the base of the middle digit ; and the outer subdivided 

 into two slips, one to join the inner tendon of a double indicator, and the 

 other to be inserted upon the middle metacarpal fascia. This hand showed 

 a remarkable complexity and profusion of the special extensor muscles. 



Out of 102 subjects this special extensor of the middle finger has been 

 found 4 times in the 68 males, and 7 times in the 34 females, giving a 

 proportionate frequency of nearly four in the latter sex to one in the for- 

 mer. It is a muscle constantly present in the Quadrumana. 



36. Extensor brevis digitorum manus. — In 3 male and 3 female sub- 

 jects, slips of muscle were found on the dorsum of the hand, arising, 

 distinct from the dorsal interossei muscles, from the os magnum or unciform 

 bones, and inserted into the common extensor aponeurosis of one or more 

 digits. In the right hand of No. 3, and the left of No. 7, males, and in 

 both hands of No. 21, a female, there was but one slip, which was inserted 

 with the tendon of the second dorsal interosseus into the middle digit. 

 In both hands of No. 2, male, there were three slips, arising respectively 

 from without inwards from the os magnum, unciform and cuneiform bones. 

 The outer was inserted with the second dorsal interosseus into the middle 

 digit — and the two inner on each side of the fifth digit, with the abductor 

 and interosseus respectively. In the female (No. 23) there were two slips. 



