224 



THE MUSCLES OF THE UPPER LIMB. 



peculiarity is sometimes associated with a change in the direction of the brachial artery. 

 An additional head of origin from the biceps or from the brachialis anticus has also been 

 observed. 



The flexor carpi radialis muscle arises from the inner condyle by the common 

 tendon, from the fascia of the forearm, and from the intermuscular septa placed 

 between it and the pronator teres on one side, the palmaris longus on the other, and 



Fig. 235. SUPERFICIAL MUSCLES OF THE FOREARM AND HAND, 



SEEN FROM THE FRONT. (Allen Thomson.) | 



3, biceps ; 3', its tendon of insertion ; 3", its aponeurotic slip ; 4, 

 brachialis anticus ; 4', its inner and lower portion ; 5', inner head of 

 the triceps ; 6, pronator radii teres ; 7, flexor carpi radialis ; 8, pal- 

 maris longus, passing at 8' into the palmar aponeurosis ; 9, flexor carpi 

 ulnaris ; 10, 10, supinator longus ; between 10 and 3', +, supinator 

 brevis ; 11, extensor ossis metacarpi pollicis ; 12, extensor brevis 

 pollicis ; 13, lower part of the flexor sublimis digitorum ; 14, flexor 

 longus pollicis ; 15, small part of the flexor profundus digitorum ; 16, 

 palmaris brevis, lying on the muscles of the little finger ; 17, abductor 

 pollicis. 



the flexor sublimis behind. The fleshy fibres end a little 

 below the middle of the forearm in a flat tendon, which 

 occupies a special compartment in the outer part of the 

 anterior annular ligament of the wrist, and running 

 through a groove in the trapezium, to which it is bound 

 by a fibrous sheath lined by a synovial membrane, is 

 inserted into the base of the second metacarpal bone, 

 a small slip being generally sent to the base of the third. 



Relations. The muscle lies immediately under the fascia 

 until its tendon sinks beneath the annular ligament. In the 

 lower half of the forearm the radial artery is placed to the 

 outer side of the tendon. 



Varieties. At its origin the flexor carpi radialis has been 

 observed receiving an additional slip from the tendon of the 

 biceps, the semilunar fascia, the coronoid process of the ulna, 

 or the anterior oblique line of the radius. Its insertion is 

 subject to frequent varieties, taking place partly into the 

 annular ligament, the trapezium, or into the fourth meta- 

 carpal bone as well as the second and third. Absence of the 

 muscle has also been met with. 



The palmaris longus, the smallest muscle of this 

 group, is placed between the flexores carpi radialis and 

 ulnaris, resting on the flexor sublimis : it arises from the 

 inner condyle, the fascia and the intermuscular septa, 

 forming a small muscular belly, which soon ends in a 



long slender tendon, inserted into the palmar fascia near the middle of the wrist, 



and often sending a slip to the abductor pollicis muscle. 



Varieties. This is probably the most variable muscle in the body. It is wanting to the 

 extent of about ten per cent, of the bodies examined. It is subject to many variations of 

 form. ; e.g., the fleshy fibres may occupy the middle of the muscle, which then commences and 

 ends by an elongated tendon ; or the muscular structure may be placed towards the lower 

 end. the upper part being tendinous ; or the whole muscle maybe reduced to a mere tendinous 

 band. A digastric muscle has also been observed. It is sometimes represented by a slip from 

 the flexor carpi ulnaris or flexor sublimis digitorum. Occasionally there are two long palmar 

 muscles, one having the ordinary shape, while the other has one of the forms above referred 

 to. An additional origin has been seen from the coronoid process, or from the radius. 



