l8o THE MUSCLES. 



tendons (Fig. yj, s') which diverge to the insertions. The 

 ulnar portion of the flexor subHmis digitorum (Fig. yy, x) takes 

 origin from the common tendon before its division. 



Insertion. — Each tendon except the first gives off a branch 

 which spreads out in the trilobed pad in the palm. The middle 

 two of these may be traced to the integument covering the pad. 

 The tendon is then inserted (Fig. 88, a) near the base of the 

 first phalanx onto the outer surface of the perforated portion of 

 the flexor sublimis tendon {b, b') at its side, except that to the 

 thumb, which divides near its distal end into two which are 

 inserted into the sesamoid bones at the base of the first phalanx. 

 The tendons of insertion are closely united to the fibrous pulley- 

 ring at the base of the first phalanx, and each may send a slip 

 to the base of the phalanx at either side of the ring. 



Relations. — Outer surface with the superficial fascia and 

 one head of the flexor sublimis (Fig. yy, x). Radial border 

 with the flexor carpi radialis. Ulnar border with the flexor 

 carpi ulnaris and a part of the flexor profundus digitorum. 

 Inner surface with the flexor carpi radialis (r), the flexor carpi 

 ulnaris (/), the flexor profundus digitorum {21), and the radial 

 head of the flexor sublimis digitorum. 



Action. — Flexor of the first phalanx of each of the digits. 



M. flexor carpi ulnaris (Fig. yy , t, t'). 



Origin. — There are two heads. The first or humeral head 

 (/') takes origin in common with the second part of the flexor 

 profundus from the median surface of the distal end of the 

 humerus just distad of the medial epicondyle (Fig. 82, (/). The 

 second or ulnar head (/) takes origin by fleshy fibres from the 

 lateral surface of the olecranon and from the dorsal border of 

 the ulna from the olecranon to a point distad of the semilunar 

 notch (Fig 87, /). The two heads join proximad of the middle 

 of the forearm. The muscle passes obliquely across the ven- 

 tral surface of the forearm to its 



Insertion by fleshy and tendinous fibres into the proximal 

 surface of the pisiform bone. 



Relations. — Outer surface with the integument and the 

 palmaris longus (Fig. yy , s). Inner surface and ulnar border 

 with the flexor profundus digitorum. 



