512 SURGICAL APPLIED ANATOMY. [Chap. xxsu. 



tendons, vessels, and nerves bound for the digits. 

 Two intermuscular septa connected with the mem- 

 brane separate the flexor brevis digitorum from the 

 abductor pollicis on the one side, and the abductor 

 minimi digiti on the other. They are, however, mem- 

 branes of too feeble a structure to much affect the 

 progress of a deep plantar abscess. 



The anterior annular ligament is divided into two 

 parts ; an upper band in front of the tibia and fibula, 

 and a lower band in front of the upper limits of the 

 tarsus. Beneath the former there is only one synovial 

 sheath, that for the tibialis anticus ; beneath the 

 latter are three sheaths : one for the peroneus tertius 

 and extensor com munis, one for the extensor proprius 

 "pollicis, and a third for the tibialis anticus. 



According to Holden, there is often a large 

 irregular bursa between the tendons of the extensor 

 longus digitorum and the projecting end of the 

 astragalus. This bursa sometimes communicates with 

 the joint of the head of the astragalus. 



Beneath the internal annular ligament are three 

 synovial sheaths for the tendons of the tibialis 

 posticus, flexor longus digitorum, and flexor longus 

 pollicis. Inflammation involving the sheath for the 

 tibialis posticus may spread to the ankle joint, with 

 which the tendon is in close relation. Beneath the 

 outer annular ligament is the single synovial sheath 

 for the long and short peroneal tendons. 



In severe sprains of the ankle not only are the 

 ligaments about the joint more or less ruptured, but 

 the various synovial sheaths just named are apt to be 

 torn. The long abiding trouble in the part that often 

 follows severe sprains depends to a great extent upon 

 damage to these sheaths, and to extravasations of 

 blood, and subsequently of inflammatory material, 

 within them. 



There are few bursae of any magnitude about the 



