One of two long bones of the forearm, located on the little finger side and forming the main hinge with the humerus at the elbow.
Structure
The ulna is wider at the elbow than at the wrist, narrowing along its length. At its proximal end the olecranon and coronoid processes grip the trochlea of the humerus, creating a deep hinge.
Landmarks
The trochlear notch on the upper end provides a secure articulation with the humerus. The olecranon forms the bony point of the elbow. The radial notch on its lateral side accepts the head of the radius.
Distal end
The ulnar head and styloid process at the wrist support the inferior radioulnar joint and a fibrocartilage disc that helps load transfer through the wrist.
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