FLEXOR SUBLIMIS DIGITORUM 



317 



which contains the radial head and the more superficial fihres of the first head, 

 the tendons to the middle and xm\£. fingers are derived. The tendon to the middle 

 finger receives the greater part of tlie radial head in penniform fashion, becoming 

 free close to the anterior annular ligament. That to the ring finger separates high 

 up, and is soon free from lleshy filjres. The deeper plane of the muscle is crossed 

 by a strong tendinous intersection soon after its origin from the first head. It then 

 gives off a fleshy band to join that part of the superficial plane which goes to the 

 ring finger, and afterwards bifurcates to form the tendons for the index and little 

 fingers. I am indebted to Professor Thane for calling my attention to this arrange- 

 ment. Beneath the anterior annular ligament the tendons of the superficial plane, 

 viz. those going to the middle and ring fingers, lie in front of the other two tendons. 

 Here they are invested by the synovial sheath or great palmar bursa., which is com- 

 mon to them and the other tendons which pass through this space, and which 



Fig. 274. — Diagram of the Great Palmar Bursa. 



Ulnar portion of palmar bursa 

 Kadial portion of palmar bursa 



Anterior annular ligament 



liumbricalis 



Deep transverse 

 ligament 



Superficial transverse ligament 



extends from a short distance above the wrist-joint to about tlie middle of the 

 palm. At the heads of the metacarpal Ijones the tendons enter the vaginal sheaths 

 of the flexors of the fingers, and each tendon becomes concave behind to correspond 

 with the convexity of the tendon of the deep flexor upon which it now rests. At 

 the middle of the first phalanx the tendon splits, and the halves sej)arate to allow 

 the passage of the tendon of the flexor profundus. The tAvo halves again unite 

 opposite the base of the second phalanx in such a way that the i)arts now in con- 

 tact are a direct continuation of what were before the borders of the tendon; while 

 the parts of the tendon which correspond to its mesial line above are now most 

 widely separated (see fig. 2S0). After a contact of about a quarter of an inch ('6 

 cm. ), the halves of the tendon again separate in order to be attached to the sides of 

 the shaft of the second phalanx. 



Nerve-supply. — From the outer and inner cords of the brachial plexus (through 



