490 THE MUSCLES AND FASCIA 



into the skin of the palm and finger, those to the palm joining the skin at the 

 furrow corresponding to the metacarpophalangeal articulation, and those to the 

 fingers passing into the skin at the transverse fold at the base of the fingers. The 

 deeper part of each slip subdivides into two processes, which are inserted into the 

 lateral margins of the anterior ligament of the metacarpophalangeal joint. From 

 the sides of these processes portions are sent backward to be attached to the bor- 

 ders of the lateral surfaces of the metacarpal bones at their distal extremities. By 

 this arrangement short channels are formed on the front of the lower ends o the 

 metacarpal bones, through which the Flexor tendons pass. 1 The intervals left 

 in the fascia between the four fibrous slips transmit the digital vessels and nerves 

 and the tendons of the Lumbricales. At the points of division of the palmar 

 fascia into the slips above mentioned numerous strong, transverse fibres bind the 

 separate processes together. The palmar fascia is intimately adherent to the 

 integument by dense, fibroareolar tissue, forming the superficial palmar fascia, 

 and gives origin by its inner margin to the Palmaris brevis; it covers the superficial 

 palmar arch, the tendons of the Flexor muscles, and the branches of the median 

 and ulnar nerves, and on each side it gives off a vertical septum, which is continu- 

 ous with the interosseous aponeurosis and separates the two lateral from the 

 middle palmar group of muscles. 



The lateral portions of the palmar fascia are thin, fibrous layers, which cover, 

 on the radial side, the muscles of the ball of the thumb, and, on the ulnar side, the 

 muscles of the little finger; they are continuous with the dorsal fascia, and in the 

 palm with the central portion of the palmar fascia. 



The Superficial Transverse Ligament of the Fingers is a thin band of transverse 

 fibres (fasciculi transversi); it 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. 



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

 inconvenient deformity known as Dupuytren'9 contraction. The ring and little fingers are most 

 frequently implicated, but the middle, the index, and the thumb may be involved. The proximal 

 phalanx is flexed and cannot be straightened, and the two distal phalanges become similarly 

 flexed as the disease advances. 



11. The Radial Region (Figs. 368, 369). 



^Abductor pollicis. Flexor brevis pollicis. 



/Opponens pollicis. Adductor obliquus pollicis. 



Adductor transversus pollicis. 



The Abductor pollicis (ra. abductor pollicis brevis) (Fig. 359) is a thin, flat 

 muscle, placed immediately beneath the integument. It arises from the anterior 

 annular ligament, the tuberosity of the scaphoid, and the ridge of the trapezium, 

 frequently by two distinct slips; and, passing outward 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 Extensor longus pollicis. 



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

 which frequently perforates it. By its deep surface, with the Opponens pollicis. Its inner 

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



1 Dr. Keen describes a fifth slip as frequently found passing to the thumb. 



