296 



DISSECTION OF THE UPPER LIMB. 



Fig. 92. 



the fibrous structures and the small vessels should be taken from the sur- 

 face of the ligaments. 



THE WRIST JOINT (fig. 92). The lower end of the radius, and the 

 first row of the carpal bones, except the os pisiforme, enter into the wrist- 

 joint. Four ligaments maintain in contact the osseous surfaces, viz., an- 

 terior and posterior, and two lateral. 

 The ulna is shut out from this articu- 

 lation by means of a piece of fibro- 

 cartilage. 



The external lateral ligament is a 

 short and strong band, which inter- 

 venes between the styloid process of 

 the radius and the outer part of the 

 scaphoid bone. 



The internal lateral ligament is 

 smaller than the external, but is 

 longer than it. It is attached by one 

 end to the styloid process of the ulna, 

 arid by the other to the rough, upper 

 part of the cuneiform bone. Some of 

 the anterior fibres are continued to the 

 pisiform bone. 



The anterior ligament (fig. 92, *) 

 takes origin from the radius and the 

 fibre-cartilage, and is inserted into 

 the first row of carpal bones, except 

 the pisiform, at the anterior surface. 



The posterior ligament (fig. 95, *) 

 is membranous, like the anterior, and 

 its fibres are directed downwards and 

 inwards. Superiorly it is attached to 

 the radius and the fibro-cartilage ; and 

 inferiorly it is fixed, like the anterior, 

 of the first row, but on the posterior 



FKONT VIEW OF THE ARTICULATIONS OF THE 

 WRIST JOINT, AND CARPAL AND META- 

 CARPAL BONES (Bourgery aud Jacob). 



1. Anterior ligament of the wrist joint. 



2. Capsule of the joint o" the metacarpal bone 



of the thumb with the os trapezium. 



3. Pisiform bone, with its separate joint and 



ligamentons bands. 



4. Transverse bands to the head of the meta- 



carpal bones. 



to the three outer carpal bones 

 aspect. 



Dissection. To see the form of the articulating surfaces, the joint 

 may be opened by a transverse incision through the posterior ligament, 

 near the bones of the carpus. 



Articular surfaces. The end of the radius, and the fibro-cartilage 

 uniting it with the ulna, form an arch for the reception of the carpal 

 bones (fig. 93) ; and the surface of the radius is divided by a prominent 

 line into an external triangular, and an internal square impression. The 

 three bones of the first carpal row constitute a convex eminence (fig. 94), 

 which is received into the hollow before mentioned in this way : The 

 scaphoid bone (a) is opposite the external mark of the radius; the semi- 

 lunar bone (&) touches the square impression, and all or part of the trian- 

 gular fibro-cartilage ; whilst the cuneiform bone (c) is in contact with the 

 capsule (Henle), and sometimes with part of the fibro-cartilage. 



The synovial membrane has the arrangement common to simple joints. 

 This joint communicates occasionally with the lower radio-Dinar articula- 

 tion by means of an aperture in the fibro-cartilage separating the two. 



Movement. The wrist is a condyloid articulation, and possesses angular 

 motion in four different directions, with circumduction. 



