MR WM. TURNER ON VARIABILITY IN HUMAN STRUCTURE. 179 



character. A more clear conception of their nature may perhaps be formed if we 

 conceive the long flexors of the digits as composed of muscles situated on two 

 planes, a superficial and a deep, and then bear in mind that both sets of muscles 

 are subdivided into bundles, each of which terminates in a tendon possessing a 

 distinct attachment to its proper digit. Now, between the different subdivi- 

 sions of the muscle or muscles, situated on the same plane, and between the 

 muscles situated on different planes, tendinous or musculo-tendinous bands not 

 unfrequently proceed so as to connect them together. Thus, whilst it is custo- 

 mary to consider the flexor sublimis as dividing into four distinct bundles, each 

 ending in a tendon, I not unfrequently saw a tendinous or musculo-tendinous 

 slip proceed between adjacent bundles, and keep up a lateral communication 

 between the divisions of the muscular mass situated on the same superficial plane. 

 In a similar manner, the divisions of the muscular mass situated on the deeper 

 plane were not unfrequently connected together by lateral bands. In the flexor 

 profundus digitorum these lateral connecting bands presented various arrange- 

 ments in different individuals. Sometimes the three inner tendons were closely 

 tied together in the forearm, either by simple bands passing from one to the 

 other, or by a more complicated reticular structure. At others only the two inner 

 tendons; at others again the tendons for the middle and ring fingers were intimately 

 connected (fig. 1), whilst the little and index tendons were quite free. As a rule, 

 indeed, the index tendon appeared to be less liable to form a connection with the 

 tendon of the same muscle than was the case with the other sub- 

 divisions of the flexor profundus. But on the other hand, I saw 

 several specimens in which the index division of the deep flexor 

 was intimately connected to the flexor longus pollicis,* a junction 

 of considerable interest, as it approximates in their arrangement 

 these muscles in the forearm and hand with the flexor hallucis 

 and flexor communis digitorum in the foot. The nature of this 

 union varied considerably in different specimens. In some it con- 

 sisted of a muscular bundle, passing obliquely downwards from 

 the fleshy part of the flexor of the thumb to the fleshy part of the 

 index division of the deep flexor ; in others it consisted of a musculo- 

 tendinous slip proceeding obliquely downwards from the muscular 

 part of the former to the tendon of the latter (fig. 1) ; and in some of these 



* Various anatomists have recognised the occasional connection of these tendons, without, how- 

 ever, specialising its different forms. See Theile, p. 246; M'Whinnie, Lond. Med. Gaz., vol. 

 xxxvii. p. 191 ; Henle, p. 196 ; Wood, Proc. Roy. Soc. of London, p. 301, 1864. I am disposed 

 to regard the connection in one or other of its forms as more common than is usually supposed. 



t Fig. 1, t, flexor longus pollicis; p, flexor profundus digitorum. It shows the connection of 

 the index tendon of the latter muscle with a strong musculo-tendinous band from the former, also 

 the close union for some distance of the middle and ring-finger tendons of the deep flexor. This, and 

 the other illustrative figures, have been drawn from the dried preparations of my dissections by my 

 pupil, Mr Richard Caton. 



VOL. XXIV. PART I. 3 c 



