PALM OP THE HAND. 151 



interossei and lumbricales muscles, and to the muscles of 

 the thumb. 



The median nerve sends an offset across the annular 

 ligament which passes down the middle of the palm and 

 unites with one of the superficial branches of the ulnar 

 nerve. 



The PALMAR FASCIA, continuous with the anterior 

 border of the annular ligament, spreads out anteriorly, 

 covering in the tendons and vessels, and opposite each 

 finger divides into slips attached to the sides of the first 

 phalanges ; between these, emerge the tendons, nerves, 

 and vessels of the fingers ; strong transverse fibres attached 

 to the phalanges on each side, called the transverse liga- 

 ment, form a framework over which is stretched the skin 

 constituting the commissures of the* fingers. The palmar 

 fascia 'is held down by fibres attached along the metacarpal 

 bones. 



The palmar fascia is to be removed with the scissors, preserving the 

 nerves and arteries beneath it ; the examination of the muscles of the 

 thumb is then to be proceeded with. 



The ABDUCTOR POLLICIS is the most superficial muscle 

 of the thumb ; it is flat and narrow, and arises from the 

 annular ligament and the os trapezium ; it is inserted into 

 the base of the first phalanx of the thumb ; it is oftentimes 

 connected at its origin with a slip from the tendon of the 

 extensor ossis metacarpi pollicis. 



The FLEXOR Ossis METACARPI POLLICIS, or OPPONENS 

 POLLICIS MUSCLE, lies beneath the preceding, its fibres pro- 

 jecting on both sides ; it arises from the annular ligament 

 and os trapezium, and is inserted into the whole length of 

 the metacarpal bone of the thumb. 



The superficialis volae branch of the radial artery crosses 

 these muscles at their origin, and either terminates in their 

 fibres, or continues on to inosculate with, the terminal part 

 of the superficial arch of the ulnar artery. It is not always 

 present. 



The FLEXOR BREVIS POLLICIS is the largest of the mus- 

 cles of the thumb ; it has two points of origin, one from 

 the annular ligament and trapezium, the other from the 

 os trapezoides and os magnum ; between these two portions 

 passes the tendon of the long flexor of the thumb, which it 

 will be remembered is a brachial muscle (p. 145); they then 

 unite into one mass, to be inserted by two heads into the 



