210 



MUSCLES OF THE UPPER LIMB 



change in tlio direction of the brachial arterj'. An additional head of origin 

 from the biceps or from the brachialis anticus has also been observed. 



Fig. 173.— SurERFiciAL Muscles op the Forearm 



AND HANP, seen from THE FrONT. (A. T.) i 



3, biceps flexor cubiti ; 3', its tendon of insertion ; 

 3", its aponeurotic slip ; 4, bracliiaUs anticus ; 4', 

 its inner and loner portion ; 5', lower part of the 

 triceps, seen arising from behind the intermuscular 

 sej)tum ; 6, pronator radii teres ; 7, flexor carpi 

 radialis ; 8, palmaris longus, passing at 8' into the 

 palmar aponeurosis ; P, flexor cari^i ulnaris ; 10, 

 supinator longus; l)et\veen 10 and 3, +, supinator 

 brevis ; 11, extensor ossis metacarpi pollicis ; 12, 

 extensor primi internodii ; 13, lower part of the flexor 

 digitorum sublimis ; 14, flexor longus pollicis ; 15, 

 small part of tlic flexor digitorum profundus ; 16, iial- 

 maris brevis, lying on the muscles of the little finger ; 

 17, abductor pollicis. 



The flexor cai'pi radialis muscle arises 

 from the inner coutlyle by the common ten- 

 don, 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 the flexor 

 sublimis posteriorly. 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 os trape- 

 zium, to which it is bound by a thin fil)rous 

 sheath lined by a synovial membrane, is 

 inserted into the base of the second meta- 

 carpal bone. 



Iidatio7is. — In the lower half of the forearm 

 the radial artery is placed to the outer side of the 

 tendon. 



Varieties. — At its origin this muscle has been 

 observed connected by an additional slip with the 

 tendon of the biceps or semilunar fascia, or with 

 the coronoid process of the ulna. Its insertion 

 has been found frequently displaced, as into 

 the trapezium, or into the thh-d and even the 

 f oiu'th metacarpal bone as well as the second. 



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 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 sometimes sending a slip to the short muscles of the thumb. 



Varieties. — This is one of the most variable muscles in the body. It is wanting 

 to the extent of alsout ten per cent, of the bodies examijied. It is subject to 

 many variations of fonn ; e.g., the muscular fibres may occupy the middle of the 

 muscle, which then commences and ends by an elongated tendon ; or the mus- 



