MET A CARPO-PHA LA NGEA L AR TIC ULA TIONS. 



267 



Metacarpo-phalangeal 

 articulation. 



3. ARTICULATIONS OF THE METACARPAL BONES WITH EACH OTHER. 



The carpal extremities of the four inner metacarpal bones articulate with 

 one another at each side by small surfaces covered with cartilages, and connected 

 together by dorsal, palmar, and interosseous ligaments. 



The Dorsal and Palmar Ligaments pass transversely from one bone to another 

 on the dorsal and palmar surfaces. The Interosseous Ligaments pass between 

 their contiguous surfaces, just beneath their lateral articular facets. 



The Synovial Membrane between the lateral facets is a reflection from that 

 between the two rows of carpal bones. 



The Transverse Metacarpal Ligaments (Fig. 178) is a narrow fibrous band which 

 passes transversely across the anterior surfaces of the digital extremities of the four 

 inner metacarpal bones, connecting 



them together. It is blended an- |( 



teriorly with the anterior (glenoid) 

 ligament of the metacarpal-phalan- 

 geal articulations. To its posterior 

 border is connected the fascia which 

 covers the Interossei muscles. Its 

 anterior surface is concave where the 

 flexor tendons pass over it. Behind 

 it the tendons of the Interossei 

 muscles pass to their insertion. 



X. Metacarpo-phalangeal Articu- 

 lations (Fig. 178). 



These articulations are of the 

 condyloid kind, formed by the re- 

 ception of the rounded head of the 

 metacarpal bone into a shallow cavity 

 in the extremity of the first phalanx. 

 The ligaments are 

 Anterior. 

 Two Lateral. 



The Anterior Ligaments (Grlenoid 

 Ligaments of Cruveilhier) are thick, 

 dense, fibrous structures, placed on 

 the palmar surface of the joints in 

 the intervals between the lateral 

 ligaments, to which they are con- 

 nected ; they are loosely united to 

 the metacarpal bone, but very firmly 

 to the base of the first phalanges. 

 Their palmar surface is intimately 

 blended with the transverse metacar- 

 pal 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 their deep 

 surface they form part of the articular surface for the head of the metacarpal bone, 

 and are lined by a synovial membrane. 



The Lateral Ligaments 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. 



Actions. The movements which occur in these joints are flexion, extension, 

 adduction, abduction, and circumduction ; the lateral movements are very limited. 



Phalangeal 

 articulations. 



FIG. 178. Articulations of the phalanges. 



