236 



THE MUSCLES OF THE UPPER LIMB. 



Relations. The palmaris brevis crosses the muscles of the little finger and covers the 

 ulnar vessels and nerve. 



MUSCLES OF THE THUMB. The short muscles of the thumb are five in number, 

 three of which, viz., the abductor, opponens, and flexor brevis, constitute the thenar 

 eminence, covering the first metacarpal bone, while the two adductors lie beneath the 

 outer part of the hollow of the palm. 



The abductor pollicis muscle, superficial and flat, arises mainly from the front 

 of the annular ligament, a few of the outer fibres being attached sometimes to the 

 ridge of the trapezium or the tuberosity of the scaphoid ; proceeding downwards and 

 outwards, it is inserted by a tendon into the base of the first phalanx of the thumb 

 at its radial border. 



The opponens pollicis muscle, placed beneath the abductor, arises from the 

 annular ligament and from the outer side of the ridge of the trapezium, and is 

 inserted into the whole length of the metacarpal bone of the thumb at the radial 

 border, as well as the adjoining part of the palmar surface. 



Fig. 242. MUSCLES AND TENDONS OP THE 



PALMAR ASPECT OP THE HAND. | 



Portions of the tendons of the superficial 

 flexor have been cut away to show those of the 

 deep flexor and the lumbricales. 1, tendon of 

 the flexor carpi radialis, cut short; 2, tendon 

 of the flexor carpi ulnaris, inserted into the 

 pisiform bone ; 3, anterior annular ligament ; 

 4, abductor pollicis ; 5, opponens pollicis ; 6, 

 flexor brevis pollicis ; 7, adductor transversus 

 pollicis ; 8, abductor minimi digiti ; 9, flexor 

 brevis minimi digiti ; 10, lumbricales. 



Fig. 243. DEEP MUSCLES OP THE 



PALM OF THE HAND. i 



The abductor pollicis and abductor minimi 

 digiti, together with the anterior annular liga- 

 ment and the flexor tendons in the palm, have 

 been removed ; in the fore finger the tendons of 

 both the superficial and deep flexors remain, in the 

 other fingers only the tendons of the deep flexor. 

 1, pronator quadratus muscle ; 2, opponens pol- 

 licis ; 3, adductor obliquus pollicis ; 4, adductor 

 transversus pollicis ; 5, opponens minimi digiti ; 

 6, unciform bone ; 7, 8, interosseous muscles. 



The flexor brevis pollicis muscle consists of two separate parts or heads, outer 

 and inner. The outer or superficial head (fig. 244) arises from the outer two-thirds 

 of the annular ligament at its lower border, and descends along the outer side of the 

 tendon of the flexor longus pollicis to be inserted into the outer side of the base of 

 the first phalanx of the thumb, having a sesamoid bone developed in it over the 

 head of the metacarpal bone. The inner or deep head (fig. 245) is very small, and 

 deeply placed between the adductor obliquus and the outer head of the abductor 

 indicis muscle. It arises from the upper part of the first metacarpal bone on the 



