28 HANDBOOK OF ANATOMY 



the radius and below to the dorsal surfaces of the proximal row 

 of bones. 



Internal Lateral ligament, attached above to the styloid process 

 of the ulna, and below to the ulnar side of the cuneiform and 

 pisiform bones. 



External Lateral ligament, attached above to the styloid pro- 

 cess of the radius, and below to the tubercle of the scaphoid. 



The synovial membrane completely lines the joint cavity, and 

 may be continuous with that of the inferior radio-ulnar joint if 

 the articular disc be perforated. 



The Interearpal Joints between the bones of the carpus are 

 all gliding joints, and they have numerous ligaments between 

 the adjacent bones ; in addition to this, the carpus is surrounded 

 by a complete capsule. 



The synoviaf membrane lines the joint, and may have a 

 separate division for the articulation between the cuneiform 

 and pisiform bones. 



Muscles acting" on the Joint. These both ventrally and 

 dorsally are arranged in two sets, superficial and deep ; on the 

 flexor (ventral) surface, the superficial group comes from the 

 inner condyle of the humerus, and the deep ones from the 

 ventral surfaces of the ulna and radius ; on the extensor (dorsal) 

 surface the superficial group comes from the outer condyle of the 

 humerus, and the deep ones from the dorsal surfaces of the ulna 

 and radius. Thus both superficial groups act on the elbow- 

 joint. 



The Carpo-Metacarpal Joints, between the five metatarsal 

 bones and the distal row of carpal bones; the first metatarsal 

 bone articulates with the trapezium, and the four inner meta- 

 tarsals articulate with the other three bones. 



First Carpo-Metaearpal Joint, between the base of the first 

 metacarpal bone and the distal surface of the trapezium. The 

 articulating surfaces of the joint are saddle-shaped, so that 

 movements occur round three axes. 



Transverse flexion and extension. 



Antero-posterior abduction and adduction (to middle line 

 of hand). 



Longitudinal rotation. 



