ARTICULATIONS OF THE PHALANGES 



321 



acts as a dorsal ligament. There is a capsular ligament which at certain points 

 has strengthening ligaments. The ligaments are: 



Anterior. 



Two Lateral. 



ARTICULAR 

 CAPSULE" 



The palmar or vaginal ligament (glcnoid ligament of Cruveilhier, ligamentum 

 vaginale) is a thick, dense, fibrous structure, placed on the palmar surface of the 

 joint in the interval between the lateral liga- 

 ments, to which it is connected; it is loosely 

 united to the metacarpal bone, but very firmly 

 to the base of the first phalanx. Its palmar 

 surface is intimately blended with the transverse 

 metacarpal ligament, and presents a groove for 

 the passage of the Flexor tendons, the sheath 

 surrounding which is connected to each side of 

 the groove. By its deep surface it forms part of 

 the articular surface for the head of the meta- 

 carpal bone, and is lined by a synovial mem- 

 brane. 



The lateral ligaments (ligamenta collateralia) 

 are strong, rounded cords placed one on each side 

 of the joint, each being attached by one extremity 

 to the posterior tubercle on the side of the head 

 of the metacarpal bone, and by the other to the 

 contiguous extremity of the phalanx. 



Movements. The movements which occur in these 

 joints are flexion, extension, adduction, abduction,, and 

 circumduction; the lateral movements are very limited. 



Surface Form. The prominences of the knuckles do 

 not correspond to the position of the joints either of the 

 metacarpophalangeal or interphalangeal articulations. 

 These prominences are invariably formed by the distal 

 ends of the proximal bone of each joint, and the line 

 indicating the position of the joint must be sought con- 

 siderably in front of the middle of the knuckle. The 

 usual rule for finding these joints is to flex the distal 

 phalanx on the proximal one to a right angle; the position 

 of the joint is then indicated by an imaginary line drawn 

 along the middle of the lateral aspect of the proximal 

 phalanx. 



XI. Articulations of the Phalanges (Articu- 

 lationes Digitorum Manus) (Fig. 258). 



These are ginglymus joints. Each joint has a 

 capsule, and certain accentuated portions are re- 

 garded as definite ligaments. These ligaments 

 are: 



ARTICULAR. 

 CAPSULE 



LATERAL 

 GAMENT 



ARTICULAR 

 CAPSULE 



are: 



LATERAL 

 LIGAMEN 



Anterior or Palmar. 



Two Lateral (ligamenta collateralia). 



FIG. 258. Metacarpal bones and first 

 phalanges of the third finger of the right 

 hand, with ligaments, from the radial side. 

 (Spalteholz.) 



The arrangement of these ligaments is similar to those in the metacarpo- 

 phalangeal articulations; the Extensor tendon supplies the place of a dorsal liga- 

 ment. 



21 



