OSTEOLOGY AND SYNDESMOLOGY. 33 
- 5. HuMeErRo-cusBiraL ARTICULATION, OR THE ELBow JOINT. In this, one 
_of the most perfect of the ginglymoid or hinge joints, the opposed extremi- 
ties of the humerus, ulna, and radius mutually receive each other, and are 
attached together by an external and internal lateral, and by an anterior 
and posterior ligament. There is no distinct capsular ligament, although 
the aggregate of these may be considered as such. 
The external lateral ligament (pl. 128, fig. 8°) arises from the external 
condyle, and is inserted into the posterior and external part of the annular 
ligament of the radius. This ligament is confounded with the tendons of 
certain muscles. The internal lateral ligament (pl. 125, fig. 15") arises from 
the inner condyle, and is inserted in a radiated manner into the inner mar- 
gin of the great sigmoid cavity of the ulna, between the coronoid and 
olecranon processes. It adheres to the synovial membrane, and, with the 
other lateral ligament, strengthens the articulation. 
The anterior ligament (fig. 12°) consists of thin fibres arising chiefly from 
_ above the internal condyle and the coronoid depression on the fore part 
of the humerus. Some are inserted into the annular ligament of the 
radius, others into the coronoid process, while the remainder are lost on 
the synovial membrane. The fibres of the posterior ligament extend chiefly 
- in a transverse direction from one condyle and one lateral ligament to the 
other. 
_ The articulations between the radius and ulna are two in number, one 
_ superior, another inferior. The shafts of the two bones are also connected 
by the interosseous ligament (fig. 16°). In the superior articulation the 
head of the radius is received into the lesser sigmoid cavity of the ulna, and 
is retained in it by the following ligament. 
The annular ligament (figs. 16°, 17°) forms about three fourths of a 
circle, the lesser sigmoid depression completing it. It arises from the 
anterior, and is inserted into the posterior border of the lesser sigmoid 
_ cavity of the ulna. It is lined by the synovial membrane of the joint; 
-it encircles the head and neck of the radius in the same manner as 
_ the transverse ligament of the atlas confines the odontoid process of the 
axis. 
The oblique ligament arises from the root of the coronoid process of the 
ulna, and is inserted into the inner side of the radius below its tubercle. 
In the inferior radio-ulnar articulation, the round. head of the ulna is 
received into the sigmoid cavity of the radius, and retained in it by a loose 
synovial membrane or the saccorm ligament (pil. 126, fig. 1"), which is 
covered before and behind by some ligamentous fibres, forming an imper- 
fect capsule, and passing from the radius to the ulna. The opposed edges 
of the shafts of both radius and ulna are connected by a thin aponeurosis 
called the interosseous membrane or ligament (pl. 125, fig. 16°*). It is not 
made very tense in any position of the limb, and serves to give attachment 
to muscles. 
6, RADIO-CARPAL ARTICULATIONS, OR THE Wrist JOINT. In this joint, 
which is of great transverse extent, the lower end of the radius and the 
inter-articular cartilage form a socket. for the scaphoid, lunar, and cuneiform 
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