Fig. 84. Region of Elbow Right Side. 



Skin, Superficial Fascia (except the Bicipital Fascia) and the upper portions of 



the Superficial Muscles arising from the Internal Condyle have been removed; 



the Pronator Radii Teres, however, is left intact. 



This figure shews the region of the Elbow, the deep layer of the Ante- 

 cubital Space and the upper third of the Forearm, from the inner side. 



The course of the Ulnar Nerve behind and below the Internal Condyle 

 is well displayed. The nerve having pierced the Internal Intermuscular Septum, 

 comes to lie behind this Septum, often embedded in the Triceps Muscle; then, 

 passing behind the Internal Condyle, it runs between the Humeral and the Ulnar 

 Origins of the Flexor Carpi Ulnaris Muscle. The Ulnar Nerve supplies the Inner 

 Head of the Triceps, and both Heads of the Flexor Carpi Ulnaris, giving off an 

 anastomotic branch to the Median Nerve. In man, only a portion of the Flexor 

 Profundus Digitorum, the slips to the 4th and 5th fingers, are supplied by the 

 Ulnar Nerve. 



Behind the Olecranon is the subcutaneous bursa which is the bursa most 

 frequently diseased, with the exception of the Patellar Bursa (Miner's Elbow). 

 Cf. Fig. 86. 



There may be a Common Ulnar Recurrent Artery (branch of the Ulnar 

 Artery) which divides into Anterior and Posterior Ulnar Recurrent Arteries, or 

 these vessels may come off directly from the Ulnar Artery. The Anterior Ulnar 

 Recurrent Artery anastomoses with the anterior division of the Inferior Profunda 

 and the Anastomotica Magna, both from the Brachial Artery, and the posterior 

 branch with the posterior division of the Inferior Profunda. 



Remarks on the Mechanics of the Elbow -Joint. 



The articular surfaces correspond to the type of hinge-surfaces, but not 

 exactly. It has been suggested that they are analogous to screw surfaces. As a 

 matter of fact, they correspond to neither type, although the Trochlea of the 

 Humerus has the shape of a screw surface shewing an inclination of 0.15 inch, 

 a lateral movement of the Ulna does not take place during flexion and extension. 

 Careful investigation shews that the axis of rotation varies constantly during 

 movement, and that the change in direction is much greater than a simple screw 

 movement would account for. — If the movement were a simple rotation, the 

 Ulna should move on the Humerus with as equal freedom as the Humerus on the 

 Ulna; this is not the case according to Otto FISCHER. 



This joint has, therefore, been described as a loose-joint, but FISCHER has 

 shewn that during life the cartilaginous coverings of the joint continuously change 

 their position and shape during movement owing to the action of the muscles 

 which press them firmly together, and that the joint is no "loose-joint". 



