ULNAR VESSELS AND NERVE. 



273 



processes, which are continued forwards, one for each finger, to the sheaths 

 of the tendons. At the point of separation of the processes from one an- 

 other some transverse fibres are placed, which arch over the lumbricalis 

 muscle, and the digital artery and nerve appearing at this spot. From the 

 pieces of the fascia a few superficial longitudinal fibres are prolonged to 

 the integuments near the cleft of the fingers. 



Dissection. To follow one of the digital processes of the fascia to its 

 termination, the superficial fibres being first removed, it must be divided 

 longitudinally by inserting the knife beneath it 

 opposite the head of the metacarpal bone. Fig- 82. 



Ending of the processes. Each process of the 

 fascia sends downwards an offset on each side of 

 the tendons, which is fixed to the deep ligament 

 connecting together the ends of the metacarpal 

 bones, and to the edge of the metacarpal bone for 

 a short distance. 



The superficial transverse ligament of the fingers 

 is a thin fibrous band, which stretches across the 

 roots of the four fingers, and is contained in the 

 fold of skin forming the rudiment of a web be- 

 tween them. Beneath it the digital nerves and 

 vessels are continued onwards to their termina- 

 tions. 



Sheath of the flexor tendons (fig. 82). Along 

 each finger the flexor tendons are retained in posi- 

 tion against the phalanges by a fibrous sheath. 

 Opposite the middle of each of the two nearest 

 phalanges the sheath is formed by a strong fibrous 

 band (e and^*) (ligamentum vaginale), which is 

 almost tendinous in consistence ; but opposite the 

 joints it consists of a thin membrane with scat- 

 tered and oblique fibres. If the sheath be opened 

 it will be seen to be lined by asynovial membrane, 

 which forms long and slender vascular folds (vin- 

 cula vasculosa) between the tendons and the 

 bones. 



Dissection. The palmar fascia, and the thinner 

 parts of the digital sheaths opposite the joints of 

 the fingers, may be taken away. On the removal 

 of the fascia the palmar arch of the ulnar artery, 

 and the median and ulnar nerves, become ap- 

 parent. 



PALMAR PART OF THE ULNAR ARTERY (fig. 

 83). In the palm of the hand the ulnar artery is 

 directed towards the muscles of the thumb, where 

 it communicates with two offsets of the radial 

 trunk, viz., the superficial volar branch (c), and 

 the branch to the radial side of the forefinger (/"). 

 The curved part of the artery, which lies across the hand, is named the 

 superficial palmar arch (rf). Its convexity is turned towards the fingers, 

 and its position in the palm would be nearly marked by a line across the 

 hand from the cleft of the thumb. 



The arch is comparatively superficial; it is covereJ. in greater part by 

 18 



THR EKTENSOR TENDON OP 

 THB FlN(}BR WITH ITS AC- 

 CESSORY MUSCLES AND 

 THE SHEATH OF THK 

 FLEXOR TENDONS. 

 a. Extensor tendon, with 6, 

 interosseous, and c, lum- 

 bricales muscles joining 

 it. 



d. Flexor tendon; e and /-, 

 thicker parts of its 

 sheath. 



0) 



bfl 



JD 

 ~0 



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