54 



THE SUPERIOR EXTREMITY 



The Synovial Membrane is attached to the margins of the 

 articular cartilages of the humerus, ulna, and radius. It then 

 covers the adjacent bone as far as the attachment of the fibrous 

 capsule, on to which it is reflected. At the distal border of the 

 annular ligament of the radius the membrane pouches down- 

 wards for a short distance around the neck of the bone. Little 

 pads of fat fill up the olecranon, coronoid, and radial fossae,, 



Posterior ligament 

 Pad of fat 



Anterior ligament 



Epiphyseal line 



Pad of fat 



Trochlea of 

 humerus 



Triceps tend 

 Bursa under triceps 



Olecranon V"Y" 

 Epiphyseal line X 



Olecranon bursa 



FIG. 1 8. Sagittal Section through the Elbow Joint. The synovial mem- 

 brane lining the joint is shown in red, the articular cartilage in light 

 blue, and the periosteum in green. The pads of fat, though intra- 

 capsular, are extra-synovial. 



but although they are intra-capsular they are covered by the 

 synovial membrane and therefore remain extra-synovial (Fig. 

 1 8). When these fatty pads hypertrophy (lipoma arborescens), 

 portions of them may project into the joint , but they are still 

 covered by a layer of synovial membrane. 



The Nerve Supply of the joint is derived from branches of 

 the Ulnar, Median, Radial (Musculo-spiral), and Musculo- 

 cutaneous nerves. 



The presence of fluid in the joint is apparent first on either 

 side of the tendon of the triceps, owing to the weakness of the 



