Fig. 85. Transverse Section through the Right Elbow-Joint. 



The section (through a frozen body) has passed, transversely to the axis of the 



Humerus, throitgli the Trochlea and Radial Head of the bone, through the 



base of the Olecranon, and the tip of the Coronoid Process of the Ulna. 



The reader looks at a right forearm from above. The Head of the Radius 

 with its elevated border lies free; the deeper middle portion is taken up b}' the 

 radial head of the Humerus. The strength of the Internal and External Lateral 

 Ligaments, the Bursa over the Olecranon, the position of the LTlnar Nerve behind 

 the Internal Condyle, and the positions of Median Nerve, Brachial Artery and 

 Musculo-Spiral Nerve on the flexor aspect are all worthy of obser\ation. The 

 Brachial Artery divides, as a rule, at the level of the line of the joint (i. e. the 

 level of this figure) into Radial and Ulnar Arteries. Below this level, the lumina 

 of these 2 arteries, one superficial (Radial Artery), and one deep (Ulnar Artery), 

 would appear in a transverse section. 



When the forearm is extended, the tip of the Olecranon Process (cf. Fig. 86), 

 lies immediately below a line connecting the 2 Condyles of the Humerus. In 

 flexion, it lies at a considerable distance below this line. Dislocation of the Ulna 

 or fracture of the Olecranon Process is present, if the Olecranon lies above this 

 line during flexion of the Forearm. 



Fig. 86. Longitudinal Section through the Left Elbow-Joint. 



The Forearm is in the position of almost co7nplete extension. The section passed 

 through the Trochlea of the Humerus, the Greater Sigmoid Cavity of the Ulna 

 and through a portion of the Radius ; it is, therefore, intermediate between a 



frontal and a sagittal section. 



Note: 



1) The Subcutaneous Bursa over the Olecranon Process. 



2) The Deep Bursa, above the Olecranon Process, situated in front (under 

 cover) of the Triceps, or in the muscle substance, just above the upper 

 recess of the Capsule of the Joint. 



3) The Bursa at the Insertion of the Biceps (Bicipital Bursa). 



The insertion of the Capsule of the Elbow-Joint on to the Humerus runs 

 along the upper borders of the 3 fossae which receive the Olecranon (posterior) 

 Coronoid Process (anterior larger) and Head of Radius (anterior smaller). These 

 three fossae are therefore intracapsular. — On the Ulna, the Capsule is attached 

 to the border of the cartilage of the Sigmoid Fossa or very near that border. — 

 On the Radius, the attachment is in the middle between the lower border of the 

 Head, and the Bicipital Tuberosity, extending lower down on the outer side than 

 on the inner. 



The Capsule itself is very thin, but it is strengthened by anterior and 

 posterior longitudinal and oblique fibres, and especially by the Lateral Ligaments, 

 an Internal and an External Ligament (cf. Fig. 85). The External Lateral Ligament 

 blends with the Orbicular Ligament, of the Radius, which surrounds the Head 

 of that bone and is attached to the Ulna. 



(Continuation next page.) 



