BLOOD-VESSELS OP THE SUPERIOR EXTREMITY. 



margin of the radius on the one side, transversely to the 

 styloid margin of the ulna and pisiforme hone on the oppo- 

 site side. This ligament presents six trochlege for the ex- 

 tensor tendons one on the styloid side of the radius for 

 the extensor ossis metacarpi and extensor minor pollicis, 

 a second for the extensor carpi radialis longior and brevior, 

 a third for the extensor major pollicis, a fourth for the 

 extensor communis and indicator, a fifth for a branch of 

 the extensor communis, and a sixth for the extensor carpi 

 ulnaris. 



The aponeurosis palmaris belongs to the hand, and covers 

 its middle palmar portion. It is triangular in shape, and 

 extends from the lower margin of the anterior annular 

 ligament and tendon of the palmaris longus to the lower 

 extremities of the metacarpal hones, where it divides into 

 four portions, each of which bifurcates to be attached to its 

 corresponding metacarpal bone, and gives passage to the 

 vessels and nerves that go to the fingers. At this point 

 the palmar fascia is strengthened by strong transverse 

 fasciculi, forming arches, beneath which pass the tendons of 

 the flexor muscles. 



Vaginal ligaments of the fingers. These are situated 

 along the ulnar and radial margins of the phalanges, and 

 are connected by transverse fibres so as to form a long tube 

 or sheath, lined by synovial membrane, in which are con- 

 tained the flexor tendons. These vaginal ligaments are of 

 a fibro-cartilaginous character, and of gieat strength, and 

 within them are observed little tendinous frfena passing 

 from the first and second phalanges, and connecting with 

 the tendons of the flexor profundus or sublimis. 



SECTION III. 



BLOOD VESSELS OF THE SUPERIOR EXTREMITY. 



The subclavian, axillary, and brachial arteries, with their 

 branches, are the sources of arterial supply of blood to the 

 shoulder, arm, forearm, and hand, comprising the upper 

 extremity. Those coming from the subclavian have been 



