OF DIDELPHYS VIRGINIANA. 119 



side, did not, in any of the specimens examined, show transverse muscular fibres correspond- 

 ing to the "palmaris brevis" of anthropotomy. The concavity of the wrist is thus arched 

 over by a fibrous band attached to the most prominent point on the radial and ulnar side. 

 The tendons of both digital flexors pass underneath this bridge ; being further bound down, 

 however, by a proper annular ligament. 



Flexor digitorum communis suhlimis s. perforatus and Flexor digitorum coinmunis 

 profundus s. perforans. — (Fig- 29,/.) In the hand the tendons of the two sets of digi- 

 tal flexors are perfectly distinct, and have precisely the characters of the human perforans 

 and perforatus. But in the arm the muscular parts are so much blended that they cannot 

 be separated without rather forcing the dissection ; their connection with the radial and 

 ulna wrist flexors, on either side, is also intimate. The fleshy portions are therefore most 

 conveniently to be considered together. The large mass of muscle occupies the whole of 

 the front of the forearm between the two wrist flexors, with very extensive origin from 

 both bony and fibrous surroundings. Of the part that chiefly represents the deep flexor, 

 an inner portion arises from the olecranon and upper two-thirds of the back of the ulna ; 

 an outer (the most distinct one) from the extremity of the inner condyle of the humerus ; 

 and a middle, from the upper half of the back of the radius, interosseous membrane and 

 contiguous surflice of the ulna. The part that represents the superficial flexor arises fi'om 

 the lowest and back part by the condyle and the contiguous part of the joint ligament. 



Imbedded in this fleshy mass lies a slender little spindle of muscle, quite distinct from 

 the rest. It may be traced entire to its origin from the very edge of the ulnar articulating 

 surface of the humerus. Its delicate tendon is lost in the common bundle of the con- 

 joined deep flexor tendons ; at least I did not succeed, after several dissections, in tracing 

 it to a digit. It seems to be the flexor longus proprius pollicis, arrested on its way to the 

 thumb. It will be shown below that the tendon of the proper long flexor of the great toe 

 is similarly attached to the common flexor of the toes. 



The tendons of the profound digital flexor are five in number — the thumb being sup- 

 plied like the other digits. They are not sepai'ated until the muscle has passed the wrist, 

 being indissolubly bound together into one stout, flattened band, and enjoying no individual 

 motion. This dense fibrous band cannot be split into five tendons without arbitrary use 

 of the knife. It fills the concavity of the front of the wrist, where it is bound down by a 

 very distinct annular ligament, different from the simple bridge formed by the pahnaris 

 longus, and so long as to be properly called a sheath. After separating on the palm, the 

 tendons pass to the fingers as stout, flattened bands, and proceed to be inserted into the 

 base of the ungual phalanges. In the palm, they are bound down by the palmar fascia; as 

 they pass along the second phalangeal internode each is bound down by a small but very 

 distinct, stout, transverse fibrous band. 



The accessory muscles (lumbricales) of the deep flexor tendons are well developed. 

 They are four in nmnber, the thumb having none. They arise from the radial side of the 

 tendons at the point of separation of the latter from each other ; and sometimes further up 

 on the conjoined tendon. They have some fascial connection with the superficial flexor 

 tendons. The four little fasciculi are perfectly distinct from each other ; they are inserted 

 on the radial sides of the bases of the four fingers, or rather into the fibrous sheath that 

 envelopes the fingers. 



The sublime flexor tendons are four in number, the thumb not being supplied ; extremely 



