Chap. XIV.] 



THE FORE-ARM. 



229 



single unsecured end of the vessel, and it, of course, 

 had also to be tied. 



There is a singular absence of large blood-vessels 

 or nerves along the posterior aspect of the fore-arm, 

 and it is significant that this is the aspect of the limb 

 most exposed to injury. For a hand's-breadth below 

 the olecranon there is almost an entire absence of 

 superficial veins. 



The median nerve passes between the two 

 heads of the pronator teres, and may possibly be com- 

 pressed by that muscle 

 when in vigorous ac- 

 tion. In this way 

 may be, perhaps, ex- 

 plained the cramp on 

 the flexor side of the 

 limb that sometimes 

 occurs after, certain 

 violent exercises. The 

 amount of muscular 

 tissue in the deep 

 head of the muscle 

 varies considerably. 



The bones of the 

 fore-arm. Trans- 

 verse sections of the 

 limb at various levels 

 show that the radius 

 and ulna are in all 

 parts nearer to the 

 posterior than the an- 

 terior aspect of the 

 extremity (Figs. 24 

 and 25). This relation is the more marked the higher 

 up the section. The two bones are nearest to the centre 

 of the limb, about the lower end of the middle third. 

 At the upper part of the fore-arm the muscles are 



Fig 1 . 24. A Transverse Section through 

 the middle of the Forerarm (Braune). 



a, Radius; &, ulna; c, supinator Ipngus ; d, 

 flexor longus pollicis : e, flexor carpi radi- 

 alis ; /, palmaris longus ; g, flexor publimis i 

 digitorum ; h, flexor carpi ulnaris ; i, flexor 

 profundus digitorum ; k, extensor carpi 

 ulnaris ; I, extensor indicis ; m, extensor 

 minimi digiti ; % extensor coinmunis digi- 

 torum ; o, extensor ossis and extensor 

 secundi internodii pollicis ; q, extenso^ 

 carpi radialis brevier ; r, extensor carpi 

 radialis longior : s, pronator radii teres ; 

 1, radial vessels and nerve ; 2, ulnar vessels' 

 and nerve. 



