366 



MUSCLES OF THE FORE-ARM. 



tendons, separated from tlie flexor longus pol- 

 licis by a deep layer of fascia, which is united 

 to the edge of the supinator radii longus on the 

 outer side, and the flexor carpi uluaris on the 

 inner side 



MUSCLES IN THE ANTERIOR REGION OF THE 

 roiiE-ABM. a. Superficial lat/er of muscles. 

 On the radial side we observe two, supinator 

 radii longus and extensor carpi rudiulis lon- 

 gior. 



1. Supinator radii longus, (grand snpina- 

 teitr, Cloq., bruchio-radialis, Socmm.,) arises 

 by a broad, flat, fleshy origin from the rough 

 ridge, on the outer side of the lower extremity 

 of the os humeri, which gradually terminates in 

 the outer condyle; it is connected at the apex of 

 its origin with the deltoid : it arises likewise 

 from the intermuscular ligaments of the upper 

 arm ; passing over the elbow-joint, its surfaces, 

 which in the upper arm face outwards and in- 

 wards, are converted into anterior and posterior 

 in the fore-arm ; opposite the tubercle of the 

 radius it becomes tendinous on its under sur- 

 face, and the fleshy fibres on its anterior face 

 entirely disappear about the middle of the fore- 

 arm in a flat tendon, which, narrowing as it 

 descends, is inserted into the external edge of 

 the base of the radius. 



This muscle at its origin has to the inner 

 side of it the brachialis anticus muscle and the 

 radial nerve and superior profunda artery; to 

 its outer side and posteriorly the triceps ex- 

 tensor cubiti; a little lower down and just 

 above the elbow-joint it has the extensor carpi 

 radialis longior to its outer side, which maintains 

 a uniform relation to it in its whole course ; in 

 passing over the elbow-joint the tendon of the 

 biceps flexor cubiti separates it from the bra- 

 chialis anticus; below the tendon of the biceps 

 muscle, we meet with, first, the pronator radii 

 teres in apposition with its internal edge ; and, 

 next, the flexor carpi radialis. In contact with 

 its posterior face superiorly is the supinator 

 radii brevis ; below this muscle the tendon of 

 the pronator radii teres; and still lower down 

 the flexor longus pollicis. 



The supinator radii longus, in addition to its 

 action as a supinator of the hand, is a flexor 

 of the fore-arm upon the arm. 



2. Extensor carpi radialis longior, (radi- 

 alis cxternus longior, Soemm., humero sus-me- 

 tacarpien, Chauss., Dumas,) arises from the 

 lower extremity of the ridge above referred to, 

 and from the outer condyle. Advancing for- 

 ward it passes over the front of the elbow- 

 joint, and soon becoming tendinous on its an- 

 terior surface descends on the anterior part of 

 the fore-arm, partly overlapped by the tendon 

 of the supinator radii longus its tendon gra- 

 dually seeks the posterior part of the arm, and 

 running through a broad shallow depression 

 appropriated to it and the second radial exten- 

 sor, finishes its course by being inserted into the 

 back part of the metacarpal bone supporting 

 the index finger. This muscle, as its name 

 implies, is an extensor of the hand, possessing 

 also a slight power in effecting its abduction. 



In the ulnar section of the anterior super- 



ficial antibrachial region we find five mus- 

 cles. 



1. Pronator radii teres arises tendinous, 

 above the elbow-joint from the intermuscular 

 ligament of the upper arm, from the front part 

 of the internal condyle of the os humeri, from 

 the process of fascia separating it from the flexor 

 carpi radialis, and from the ulna close to the 

 insertion of the brachialis anticus. This muscle, 

 though tendinous at its origin, soon becomes 

 fleshy, and from its rounded form, which causes 

 a distinct projection beneath the skin at the front 

 and upper part of the fore-arm, derives its name. 

 Its fleshy fibres terminate in a tendon as it 

 enters the radial section, which gradually be- 

 comes wider as it descends, and sliding behind 

 the supinator radii longus and extensor carpi 

 radialis and in front of the radius, is inserted 

 into the outer and back part of that bone. The 

 pronator radii teres has to its outer side, supe- 

 riorly, the tendon of the biceps muscle; below the 

 tubercle of the radius it has the internal edge of 

 the supinator radii longus in apposition with 

 it, and as it slides in a spiral direction round 

 the radius, and behind this muscle, it has the 

 supinator radii brevis superior and external to 

 it ; to its inner side it has throughout its course 

 the flexor carpi radialis. 



In the ulnar section the anterior surface of this 

 muscle is in contact with the fascia; in the 

 radial it is covered by the supinator radii 

 longus, the two radial extensors, and crossed 

 by the radial artery and nerve. The posterior 

 surface of this muscle is in contact with the 

 anterior ligament of the elbow-joint, the bra- 

 chialis anticus, the median nerve, ulnar artery, 

 the flexor communis digitorum sublimis and 

 radius. This muscle, while presenting a smooth 

 and tendinous face to the under surface of the 

 supinator longus and radial extensors, conti- 

 nues fleshy on its under surface to the very 

 point of its connexion with the radius, the 

 muscle beneath, whose surface is in contact 

 with its fleshy fibres, being clothed in a similar 

 manner with tendon ; this admirable contri- 

 vance for preventing friction is by no means 

 peculiar to this situation, though its utility is 

 frequently overlooked. 



The name of this muscle indicates its action 

 as a pronator of the hand, and when that 

 effect has been produced, if its contractile 

 power be still further excited, it will flex the 

 fore-arm upon the upper. In case of fracture 

 of the radius, this power is excited injuriously 

 in bringing the radius across the ulna, and thus 

 obliterating the interosseal space, and if not 

 corrected by the surgeon, causing unnatural 

 union of the two bones. 



2. Flexor carpi radialis ( M. radialis intcrnus, 

 Winslovv, Albinus, Lieutaud, Sabatier, Soemm.; 

 grand palaHiire, or radial anterieur, Cloquet;) 

 arises from the internal condyle of the humerus 

 in common with the last-mentioned muscle; at 

 the point where these two muscles are con- 

 nected with the humerus there exists no na- 

 tural separation between them. About an inch 

 and a half from their origin a separation is 

 effected by the dipping in of the fascia forming 



