The elbow is one of two bones that give the forearm structure. The elbow is on the opposite side of the forearm from the thumb. It connects the humerus at its major end, forming the elbow joint and connects to the wrist bones of the hand at its smaller end. Along with the radius, the elbow allows the wrist to rotate.


The diameter of the ulna is 50% greater than the radius from 4 to 5 months. During adult life, when remodeling and resorption are completed, the diameter of the elbow becomes half the radius. The elbow bone is found and has a similar function both in humans and in four-legged animals such as dogs and cats.

In the event of a rupture of the ulna bone, it most often occurs in a place where the radius and elbow form a joint or where the ulna bone forms a joint with the wrist bones of the hand. Elbow fractures cause severe pain, difficulty in moving the joint, and even deformation of the arm if the fracture is complex.


More ulna functions

The humerus, on the right side of the elbow as a hinged joint with a crescent-like excision of the ulna. The radius, close the elbow as the pivot point, allows the radius to cross the ulnar in the pronation. In the ulna functions, distal radius, where it fits the elbow notch. Radius along its length through the interosseous membrane that forms the syndesmosis joint.


Development of ulna

The elbow bone is ossified from three centers: one for the body, the tip of the wrist and the tip of the elbow, near the top of the olecranon. The ossification begins near the center of the ulnar, about the eighth week of fetal life, and soon extends over most of the bones.


After birth, the ends are cartilaginous. More or less in the fourth year, the center appears in the middle of the head and soon extends to the process of appendicitis of the ulna. Around the tenth year, a center appears in the olecranon near its end, the main part of which is the extension of the body. The upper base connects to the body around the sixteenth, lower around the twentieth year.

Structure of ulna

The elbow long bone finds in the forearm that extends from the elbow to the smallest finger, and when it is in the anatomical position, is located on the middle side of the forearm. It is wider near the elbow and narrows as it approaches the wrist.

Ulna functions

The elbow bone is located near the elbow in the bone process, and an olecranon process resembling a hook that fits the bottom of the humerus olecranon. This prevents overstressing and creates a hinged connection with the humerus. There is also a radial excision for the head of the ray and the lumpiness of the nodule to which the muscles attach.