THE UPPER LIMB 375 



ligament, and reaches upwards to the same height as the inner 

 compartment. Interiorly it is prolonged uninterruptedly along the 

 tendon to its insertion, so that it is continuous with its synovial 

 sheath on the thumb. The disposition of the great palmar bursa 

 in relation to the thumb and little finger is to be carefully noted in 

 connection with whitlow of these fingers. It will be evident that 

 pus could readily burrow upwards from the thumb and little finger 

 into the lower part of the forearm, passing in its course beneath the 

 anterior annular ligament. 



Anterior Annular Ligament 



Synovial Sheath of Thumb 

 Great Palmar Bursa 



_ . SjTiovial Sheath of 

 Little Fingtr 



Fig. 201. — The Great Palmar Bursa, and the SyNOViAi, 

 Sheaths of the Flexor Tendons. 



Sheaths of the Flexor Tendons. — As the superficial and deep flexor 



tendons pass along the fronts of the four inner fingers each pair is 

 ■-ontained in a fibro-osseous canal. The osseous wall is formed by 

 the palmar aspects of the first and second phalanges, and the fibrous 

 .vail by a sheath. This sheath, over the greater parts of the first 

 ind second phalanges, is thick and strong, and these parts of it 

 ,ire known as the vaginal ligaments. The fibres of these ligaments 

 j"un transversely, and are attached to the rough lateral margins of 

 he palmar surfaces of the phalangeal shafts. Opposite the joints, 

 n order not to interfere with flexion, the vaginal ligaments are 

 -^laced by thin membranes, superadded to which are obliquely 



