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Lower extremity of humerus
The lower extremity of the humerus is flattened from before backward, and curved slightly forward; it ends below in a broad, articular surface, which is divided into two parts by a slight ridge.
Projecting on either side are the lateral and medial epicondyles.
The articular surface extends a little lower than the epicondyles, and is curved slightly forward; its medial extremity occupies a lower level than the lateral.
The lateral portion of this surface consists of a smooth, rounded eminence, named the capitulum of the humerus; it articulates with the cupshaped depression on the head of the radius, and is limited to the front and lower part of the bone.
On the medial side of this eminence is a shallow groove, in which is received the medial margin of the head of the radius.
Above the front part of the capitulum is a slight depression, the radial fossa, which receives the anterior border of the head of the radius, when the forearm is flexed.
The medial portion of the articular surface is named the trochlea, and presents a deep depression between two well-marked borders; it is convex from before backward, concave from side to side, and occupies the anterior, lower, and posterior parts of the extremity.
The grooved portion of the articular surface fits accurately within the semilunar notch of the ulna; it is broader and deeper on the posterior than on the anterior aspect of the bone, and is inclined obliquely downward and forward toward the medial side.
Above the front part of the trochlea is a small depression, the coronoid fossa, which receives the coronoid process of the ulna during flexion of the forearm.
Above the back part of the trochlea is a deep triangular depression, the olecranon fossa, in which the summit of the olecranon is received in extension of the forearm.
These fossæ are separated from one another by a thin, transparent lamina of bone, which is sometimes perforated by a supratrochlear foramen; they are lined in the fresh state by the synovial membrane of the elbow-joint, and their margins afford attachment to the anterior and posterior ligaments of this articulation.
The epicondyles are continuous above with the supracondylar ridges.
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Lower_extremity_of_humerus". A list of authors is available in Wikipedia.|