FORE- ARM. 



363 



Of the different morbid growths which arise 

 in the cellular tissue of the fore-arm, those 

 which are superficial and those, which are 

 beneath the fascia require careful distinction, 

 the removal of the former being easily effected, 

 while all operations on the latter require great 

 consideration and care. 



The superficial tumour projects under the 

 skin, creating some deformity ; it may be 

 moved with facility, for its attachments are 

 loose ; while, on the other hand, the deep- 

 seated or sub-fascial tumour has frequently a flat- 

 tened surface, and often appears, on superficial 

 examination, insignificant and of small extent, 

 while in fact its mass is considerable, bur- 

 rouing deeply between the muscles. It is to 

 be distinguished from the supra-fascial tumour 

 by its comparative immobility, by the various 

 effects produced upon it by the fascia when 

 in a state of tension or relaxation, by the pain 

 produced by pressure on nerves, or impediment 

 to the circulation from pressure on the vessels. 

 In the removal of the sub-fascial tumour the 

 operator must call to mind the direction and 

 relative position of the muscles in the neigh- 

 bourhood of it, as the roots or under surface 

 of these generally follow the interspace between 

 the muscles, and are thus guided to a great depth 

 among the vessels and nerves of the^fore-arm. 



The same principles apply to the diagnosis 

 and treatment of superficial and deep-seated 

 abscesses. The superficial abscess is less cir- 

 cumscribed ; the matter is diffused without 

 limit through the subcutaneous tissue; from 

 its position the absorption of the superincum- 

 bent tissues takes place rapidly, the skin either 

 giving way entirely without the aid of the 

 surgeon, or else pointing at some particular 

 spot indicates where the abscess lancet may be 

 employed with advantage. 



The sub-fascial abscess, on the contrary, pro- 

 ceeds slowly in many cases, and even insidiously, 

 bound down by the unyielding fascia ; it tells 

 us of its presence, in the first instance, rather 

 by the constitutional disturbance which it 

 rouses than any striking indications of local 

 mischief. These abscesses are occasionally the 

 consequence of inflammation commencing in 

 the theca of the flexor tendons, and the bur- 

 rowing of the matter upwards in the course of 

 the tendons. The septa of the fascia, which 

 have been described passing down between the 

 muscles to the bone, limit the passage of the 

 pus in different directions. 



The fascia itself is not much subject to 

 disease, though it seems peculiarly disposed to 

 slough as a consequence of phlegmonous ery- 

 sipelas. 



Vessels. The main arteries of the fore-arm are 

 the radial and ulnar, into which the brachial 

 artery divides just below the bend of the elbow. 

 The brachial artery at this spot has on its outer 

 side the tendon of the biceps ; on its innpr 

 side, one of the venae comites, the median 

 nerve, and the pronator radii teres muscle. 

 Behind the brachial artery is the brachialis 

 anticus muscle, and in front of it the fascial 

 insertion of the biceps muscle. 



The radial artery, which is the smaller of 

 the two divisions, pursues nearly the same 

 direction as the brachial, and in the lower part 

 of the upper third of the fore-arm is found 

 exactly midway between the radial and ulnar 

 surfaces, overlapped by the supinator radii 

 longus, and lying upon the tendon of the 

 pronator radii teres muscle, with the radial 

 nerve about a quarter of an inch to its outer 

 side, and separated by fat and cellular mem- 

 brane. From this point the radial artery 

 descends towards the wrist-joint, and at the 

 lower part of the upper half of the fore-arm 

 quits the pronator radii teres, and passes on to 

 the anterior surface of the flexor longus pollicis, 

 having the flexor carpi radialis to its inner side. 

 A little lower down, that is, at the upper part 

 of the lower third, the vessel emerges from 

 beneath the supinator radii longus muscle, and 

 is covered only by the fascia. In its further 

 course to the wrist-joint the flexor carpi radialis 

 maintains its position on the inner side, to 

 which the tendon of the supinator radii longus 

 corresponds on the outer. The radial nerve 

 no longer accompanies the vessel, for it has 

 now slid under the supinator radii longus, and 

 reached the posterior face of the arm. As the 

 radial artery just above the wrist-joint is 

 covered only by the fascia, and lies upon the 

 bone, its pulsations are easily felt, and in con- 

 sequence of its convenient situation is generally 

 selected by the medical practitioner to ascertain 

 the general state of the circulation. We should, 

 however, always bear in mind the great variety 

 both in size and distribution to which this 

 vessel is liable, and take the precaution of at 

 least examining the radial artery in both 

 arms. 



The inner edge of the supinator radii muscle 

 is a certain guide to the situation of this artery 

 should the surgeon be required to secure it, 

 and this should always be effected by two 

 ligatures, as its free anastomosis below will 

 certainly produce secondary hemorrhage if this 

 precaution is neglected. As the nerve lies 

 on the outer side of the artery, the needle 

 must be passed from without inwards. 



The ulnar artery has a deep course, first 

 passing beneath the median nerve, which se- 

 parates it from the pronator radii teres muscle,, 

 next beneath the flexor digitorum sublimis, 

 the two last muscles separating it from the 

 flexor carpi radialis and palmaris longus, and 

 upon the flexor digitorum profundus, and when 

 it reaches the tendon of this muscle midway 

 between the wrist and elbow-joints, it comes 

 into contact with the ulnar nerve, by which 

 it is separated from the flexor carpi ulnaris 

 muscle on its inner side. In its further descent 

 to the wrist-joint it is situated between the 

 flexor communis digitorum sublimis and flexor 

 carpi ulnaris. Gradually sliding behind, the 

 tendon of the latter remains covered by it 

 for about two inches above the annular liga- 

 ment of the wrist, in front of which it passes 

 into the palm of the hand. The third branch 

 worthy of mention in this division of the fore- 

 arm is the anterior interosseal. This vessel 



