234 HISTORY OF THE HUMAN BODY 



of a system of flexors, there are two sets of short flexors, Mm. 

 flex ores breves superficiales and flexor 'es breves profundi, each 

 consisting of four muscles, one to each digit. The super- 

 ficiales arise from the distal row of carpalia, and pass into ten- 

 dons, which, encountering the long slips of the aponeurosis, 

 divide into two lateral tendons and insert upon the sides of the 

 penultimate phalanges. The flexores profundi lie close to the 

 bone, arise beneath the former, and insert into the bases of the 

 proximal phalanges. There are here also, as on the dorsal 

 side, two long muscles which arise from the humerus and insert 

 along the shafts of radius and ulna and into the corresponding 

 sides of the carpals, serving as flexors of antebrachium and 

 manus as a whole. These are respectively the flexor radialis 

 and flexor ulnaris (fr and fu). 



.The ventral muscles thus far enumerated, act either directly 

 or indirectly as flexors, but beneath all of these is a set of short 

 abductors and adductors of the metacarpals, abductores and 

 adductores breves, which correspond in function to the large 

 muscle mass of the dorsal aspect, M. dorsalis antebrachii, with 

 its abductor and adductor tendons. These extend across the 

 interval between the distal carpalia and the metacarpals, and 

 like those of the dorsal mass, supply both sides of the two inner 

 digits, III and IV, and the inner sides of II and V. As in 

 the case of the abductor and adductor system of the dorsal side, 

 M. dorsalis antebrachii, the internal (radial) side of digit II 

 remains unsupplied from this system and the deficiency is made 

 good by the pronator (pr), a muscle which lies obliquely across 

 the antebrachium and is related to the skeletal parts precisely 

 as is the supinator of the dorsal side. Like the latter it arises 

 from the shaft of the ulna and passes obliquely downwards to 

 the radial side of the limb, where it inserts by a tendon into the 

 radial side of the base of metacarpal II. 



Deepest of all, beneath the short abductors and adductors, 

 and reached equally well from either dorsal or ventral aspect, 

 a set of three intermetacar pales stretch their fibers across the 

 interspaces between the separate metacarpals and act either as 



