Fig. 96. Palm of Hand (Left); Deep Layer. 



In addition to those structures removed in Fig. pj, the distal portions of the 

 Flexor Sublimis Digitorum and flie Flexor Profundus Digitorum (except in 

 connection ivith the little finger) muscles, the Palmaris Longns Muscle, the 

 Superficial Palmar Arch and the deep fascia of the hand have been cut away. 

 A piece of the Abductor Pollicis Muscle has been excised, and the Pronator 



Quadratus Muscle exposed. 



The Deep Palmar Arch formed by the junction of the deep branch of 

 the Ulnar Artery with the deep division of the Radial Artery lies at a deeper 

 plane than the flexor tendons and the deep fascia, practicalh', in the middle 

 between the superficial arch and the distal border of the carpal bones, on the 

 bases of the metacarpal bones nearer the dorsal than "the palmar aspect of the 

 hand (cf. Figs. 97 — 104). 



The deep division of the Ulnar Nerve accompanies the deep arch as far 

 as the Adductor Transversus Pollicis Muscle and the ist Dorsal Inter-osseous 

 Muscle, passing on to suppl}^ all the Interosseous muscles, having given off, in 

 its course, the fibres to the Hypothenar Group of Muscles and the two inner 

 Lumbricalis muscles. 



The tendons and their sheaths run in an Osseo - Aponeurotic Canal 

 (cf. Figs. g8 — loi). Most important is the relation which the flexor tendons bear 

 to the phalanges. When these tendons are divided near the base of the terminal 

 phalanx no suture is required, as it is quite sufficient to fix the finger in the 

 position of flexion; but if the division should occur at the intermediate phalanx, 

 suture of the cut ends of the tendon is necessary. 



The Flexor Profundus perforates the Flexor Subhmis tendon at the first 

 interphalangeal articulation ; accordingly at this point there are three tendinous 

 strands. At the base of the first Phalanx (proximal phalanx) there are only two 

 tendons to be sewn together. The flexor tendons are enclosed within a fascial 

 canal and often retract considerablj' towards the muscular portion when divided. 

 The distal end retracts to a marked extent when the injury occurs in extreme 

 flexion (e. g. when a bottle breaks in the hand). 



Under such conditions it ma\' be necessary to open up the tendon-sheath 

 which is relatively thin at the joints (where it is reinforced by a few delicate 

 transverse and oblique fibres) but dense opposite the shaft of the first and second 

 phalanges. 



In addition to the sensory communication shown in Fig. 95 as a loop 

 around the Ulnar Artery and the motor communication in the 3rd Lumbrical 

 Muscle, others occur. One inconstant communication occurs between the dorsal 

 branch of the Ulnar Nerve and the branch to the inner aspect of the little finger. 

 Another of greater constancy passes through the Adductor Transversus Pollicis 

 Muscle where becoming more superficial it winds round the Flexor Longus 

 Pollicis Muscle and joins the Muscular branch of the Median Nerve. 



