METACARPO-PHALANGEAL JOINTS 211 



move volarwards. The metacarpal bone of the little finger is provided 

 with an opponens muscle, and has a feeble power of moving volarwards 

 and laterally towards the thumb. 



The carpo-metacarpal and intermetacarpal joints are supplied by the 

 radial, ulnar and median nerves. 



ARTICULATIONES METACARPOPHALANGE^E ET DIGITORUM 

 (METACARPO-PHALANGEAL AND INTERPHALANGEAL JOINTS). 



The ligaments which connect the metacarpal bones with 

 the phalanges and those which connect together the 

 phalanges of adjacent rows are practically similar in character 

 although the joints belong to different groups. The ligaments 

 of each joint are : 



1. Capsula articularis. 



2. Lig. accessorium volare. 



3. Ligg. collateralia. 



Capsula Articularis. The fibrous stratum of the articular 

 capsule is blended, on the volar aspect, with the accessory 

 volar ligament and at the sides with the collateral ligaments. 

 Dorsally it is absent, and there the synovial stratum of the 

 capsule lies in direct relation with the extensor tendon or 

 tendons which cross the joint. 



Ligamentum Accessorium Volare. The volar accessory 

 ligament is a strong fibrous plate which is firmly attached to 

 the volar aspect of the base of the distal bone of the joint. 

 It extends proximally over the volar aspect of the head of 

 the proximal bone of the joint and is loosely attached to its 

 neck. Its margins are connected with the collateral ligaments 

 and with the fibrous flexor sheath of the finger. The volar 

 surfaces of the volar accessory ligaments of the metacarpo- 

 phalangeal joints are grooved by the flexor tendons and they 

 are connected with one another by the transverse ligament 

 of the heads of the metacarpal bones. Two sesamoid bones 

 are usually developed in the volar accessory ligaments of the 

 metacarpo-phalangeal joint of the thumb and not uncommonly 

 sesamoid bones are found in the corresponding ligaments of 

 other metacarpo-phalangeal joints (Figs. 98, 99). 



Dissection. The extensor tendons should now be raised 

 from the dorsal surfaces of the metacarpo-phalangeal joints. 

 If this is done carefully the dorsal part of the capsule of each 

 joint will be left intact. It is very thin, and consists, practically, 

 i Ha 



