86 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



torsion," which does not exist in the fetus; this allows the 

 hand to serve the purposes of the head and mouth. A small 

 hooked supracondylar process is sometimes found about two 

 inches above the inner epicondyle. 



THE BONES OF THE FOREARM 



The Ulna 



This is the internal of the two bones of the forearm. It 

 articulates with the humerus, radius, and the triangular articulo- 

 cartilage at the wrist. It presents for examination a shaft and 

 two extremities. 



The upper extremity presents two processes and two articular 

 concavities. 



The olecranon process forms the uppermost part of the ulna. 

 It terminates superiorly in front in a beak which overhangs 

 the great sigmoid cavity; behind this is a rectangular tuberosity, 

 forming the point of the elbow. It has superiorly a quadri- 

 lateral surface, transversely grooved in front for attachment 

 of the posterior ligament of the elbow; behind this it gives 

 attachment to the triceps. The posterior surface of the olec- 

 ranon is triangular and subcutaneous, covered by a bursa, 

 and continuous with the posterior border of the ulna. 



The lateral surfaces show anteriorly continuations of the 

 groove just mentioned, the inner for the posterior portion of 

 the internal lateral and the external for part of the posterior 

 ligament of the elbow. Internally there is also attached a 

 portion of the flexor carpi ulnaris; externally the anconeus. 

 The anterior surface is smooth, curved forward above, and 

 forms the upper and part of the greater sigmoid cavity. The 

 inferior surface, or base, is attached to the shaft. 



The coronoid process is a rough triangular eminence pro- 

 jecting forward from the anterior aspect of the ulna just below 

 the olecranon. Its base is large and firmly united to the shaft. 

 Its upper surface is smooth, concave, formirig the inferior 

 portion of the greater sigmoid cavity and the lowest part of 

 the back of that cavity. Its apex is bluntly pointed, and 

 curved slightly upward. The under surface is rough, con- 

 cave, looking downward and outward. At the junction of 



