76 PHYSIOLOGICAL SERIES. 



muscle passing along the upper part of the articular cavity, 

 and attached to the marginal ligament of the glenoid cavity 

 of the scapula. The section of the capsular ligament 

 shows its relative thickness at the upper and lower part. 

 0. C. 255. Hunterian. 



ELBOW. 



B. 139. Right elbow of a Frog (Rana clamata) in which the 

 articular surfaces have been exposed. The bone formed 

 by the fusion of radius and ulna articulates by a simple 

 concave facet with the single hemispherical condyle of the 

 humerus. The internal epicondyle is prominent, and bears 

 on its median surface a facet, which engages with a 

 corresponding facet on the inner surface of the ulna head. 

 The form of the articular surfaces indicates a very consider- 

 able freedom of movement in all directions except towards 

 the inner side, where it is checked by the epicondylo-ulnar 

 articulation. 



Cuenod, Internat. Jour. Anat. & Physiol., vol. v. 1888, 

 p. 390. 



B. 140. Right elbow-joint of a Turtle (Chelone mydas}. The 

 articular surface on the humerus for the radius is rounded 

 and smaller than that for the ulna. A fold of the 

 capsule projects from behind. 



Presented by George Ring, Esq. 



B. 141. Right elbow-joint of a Goose (Anser domesticus] opened 

 from the flexor aspect to show the form of the joint surfaces. 

 The curvatures of the two humeral condyles are eccentric 

 to the axis of rotation of the joint in different directions, 

 so that in extension the radius is drawn towards the shoulder 

 and the ulna protruded in flexion the reverse. The 

 horizontal gliding of the radius upon the ulna is assisted by 

 the presence of articular facets where the two bones touch, 

 and by a band of fibro-cartilage (indicated by a black 

 bristle) stretched between the dorsal borders of their heads. 

 By this movement of the radius, the hand, upon extension 

 of the elbow, is automatically brought into line with the 



