404 THE MUSCLES AND FASCIA. 



The Superficial Transverse Ligament of the Fingers is a thin, fibrous band 

 which stretches across the roots of the four fingers, and is closely attached to the 

 skin of the clefts, and internally to the fifth metacarpal bone, forming a sort of 

 rudimentary web. Beneath it the digital vessels and nerves pass onward to their 

 destination. 



Surgical Anatomy. The palmar fascia is liable to undergo contraction, producing a -very 

 inconvenient deformity known as " Dupuytren's contraction." The ring and little fingers are 

 most frequently implicated, but the middle, the index, and the thumb may be involved, 

 proximal phalanx is drawn down and cannot be straightened, and the two distal phalanges 

 become similarly flexed as the disease advances. 



2. Radial Region (Figs. 242, 243). 



Abductor pollicis. Flexor brevis pollicis. 



Opponens (Flexor ossis metacarpi) pollicis. Abductor obliquus pollicis. 

 Adductor transversus pollicis. 



The Abductor pollicis is a thin, flat muscle, placed immediately beneath the 

 integument. It arises from the annular ligament, the tuberosity of the scaphoid, 

 and the ridge of the trapezium, frequently by two distinct slips ; and, passing out- 

 ward and downward, is inserted by a thin, flat tendon into the radial side of the 

 base of the first phalanx of the thumb, sending a slip to join the tendon of the Ex- 

 tensor longus pollicis. 



Relations. By its superficial surface, with the palmar fascia and superficialis 

 volse artery, which frequently perforates it. By its deep surface, with the Op- 

 ponens pollicis, from which it is separated by a thin aponeurosis. Its inner border 

 is separated from the Flexor brevis pollicis by a narrow cellular interval. 



The Opponens pollicis (Flexor ossis metacarpi pollicis) is a small, triangular 

 muscle, placed beneath the preceding. It arises from the palmar surface of the 

 ridge on the trapezium and from the annular ligament, passes downward and out- 

 ward, and is inserted into the whole length of the metacarpal bone of the thumb on 

 its radial side. 



Relations. By its superficial surface, with the Abductor and Flexor brevis 

 pollicis. By its deep surface, with the trapezio-metacarpal articulation. By its 

 inner border, with the Adductor obliquus pollicis. 



The Flexor brevis pollicis consists of two portions, outer and inner. The outer 

 and more superficial portion arises from the outer two-thirds of the lower border of 

 the annular ligament, and passes along the outer side of the tendon of the Flexor 

 longus pollicis ; and, becoming tendinous, has a sesamoid bone developed in its 

 tendon, and is inserted into the outer side of the base of the first phalanx of the 

 thumb. The inner and deeper portion of the muscle is very small, and arises from 

 the ulnar side of the first metacarpal bone beneath the Adductor obliquus pollicis, 

 and is inserted into the inner side of the base of the first phalanx with this muscle. 



Relations. By its superficial surface, with the palmar fascia. By its deep 

 surface, with the tendon of the Flexor longus pollicis. By its external surface, 

 with the Opponens pollicis. Behind, with the Adductor obliquus pollicis. 



The Adductor obliquus pollicis arises by several slips from the os magnum, the 

 bases of the second and third metacarpal bones, the anterior carpal ligaments, and 

 the sheath of the tendon of the Flexor carpi radialis. From this origin the greater 

 number of fibres pass obliquely downward and converge to a tendon, which, 

 uniting with the tendons of the deeper portion of the Flexor brevis pollicis and 

 the Adductor transversus, is inserted into the inner side of the base of the first 

 phalanx of the thumb, a sesamoid bone being developed in the tendon of insertion. 

 A considerable fasciculus, however, passes more obliquely outward beneath the 

 tendon of the long flexor to join the superficial portion of the short flexor and the 

 Abductor pollicis. 1 



1 This muscle was formerly described as the deep portion of the Flexor brevis pollicis. 



