THE CARPAL JOINTS 



269 



(a) The Joints of the First Row of Carpal Bones 

 Class. — Diarthrosis. Subdivision. — Arthrodia. 



The bones of the first row, the pisiform excepted, are united by two sets of 

 ligaments and two interosseous fibro-cartilages. 



Dorsal. Volar. 



Interosseous. 



The two dorsal intercarpal ligaments extend transversely between the bones, and connect 

 the navicular with the lunate, and the lunate with the triquetral. Their posterior surfaces are 

 in contact with the posterior ligament of the wrist. 



The two volar intercarpal ligaments extend nearly transversely between the bones connect- 

 ing the navicular with the lunate, and the lunate with the triquetral. They are stronger than 

 the dorsal ligaments, and are placed beneath the anterior Ugament of the wrist. 



The two interosseous intercarpal ligaments (fig. 304) are interposed between the navicular 

 and lunate, and the lunate and triquetral bones, reaching from the dorsal to the volar siu-faces. 



Fig. 303. — Posterior View of the Wrist, with Capsule cut to show Articular Surfaces, 



f^^ — I Lower end of interosseous ligament 



Inferior oblique ligament 



Articular disc 



Band of posterior ligament of wrist 

 left to keep bones in situ 



Transverse dorsal ligament 



Tendon flexor carpi ulnaris 



and being connected with the dorsal and volar ligaments. They are narrow fibro-cartilages 

 which extend between small portions only of the osseous surfaces. They help to form the 

 convex carpal siu-face of the radio-carpal joint, and are somewhat wedge-shaped, their bases 

 being toward the wrist, and their thin edges between the adjacent articular surfaces of the bones. 



The synovial membrane is a prolongation from that of the medio-carpal joint. 



The arterial and nerve -supplies are the same as for the medio-carpal joint. 



The Joint of the Pisiform Bone with the Triquetral 



This is an arthrodial joint which has a loose fibrous capsule attached to both 

 the pisiform and triquetral bones just beyond the margins of their articular 

 surfaces. 



It is lined by a separate synovial membrane. Two strong rounded or flattened bands pass 

 downward from the pisiform, one +o the process of the hamate [Hg. pisohamatum], and the 

 other [hg. pisometacarpeum] to the bases of the third to fifth metacarpals; these are regarded as 

 prolongations of the tendon of the flexor carpi ulnaris, and the pisiform bone may be looked 

 upon in the light of a sesamoid bone developed in that tendon. 



(6) The Joints of the Second Row of Carpal Bones 

 Class. — Diarthrosis. Subdivision.— ^r^/irodta. 



The four bones of this row are united by three dorsal, three palmar, and three 

 interosseous ligaments. 



