Olecranon
Encyclopedia
The olecranon is a large, thick, curved bony eminence of the forearm that projects behind the elbow
.
It is situated at the upper (proximal) end of the ulna
, one of the two bones in the forearm
. When the hand faces forward (supination
) the olecranon faces towards the back (posteriorly).
It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa
of the humerus
in extension of the forearm.
Its base is contracted where it joins the body and the narrowest part of the upper end of the ulna.
Its posterior surface, directed backward, is triangular, smooth, subcutaneous, and covered by a bursa
.
Its superior surface is of quadrilateral form, marked behind by a rough impression for the insertion of the Triceps brachii; and in front, near the margin, by a slight transverse groove for the attachment of part of the posterior ligament of the elbow-joint.
Its anterior surface is smooth, concave, and forms the upper part of the semilunar notch
.
Its borders present continuations of the groove on the margin of the superior surface; they serve for the attachment of ligaments, viz., the back part of the ulnar collateral ligament medially, and the posterior ligament laterally.
From the medial border a part of the Flexor carpi ulnaris arises; while to the lateral border the anconeus muscle
is attached.
Elbow
The human elbow is the region surrounding the elbow-joint—the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm....
.
It is situated at the upper (proximal) end of the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
, one of the two bones in the forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
. When the hand faces forward (supination
Supination
Supination is a position of either the forearm or foot; in the forearm when the palm faces anteriorly, or faces up . Supination in the foot occurs when a person appears "bow-legged" with their weight supported primarily on the anterior of their feet.The hand is supine in the anatomical position...
) the olecranon faces towards the back (posteriorly).
It is bent forward at the summit so as to present a prominent lip which is received into the olecranon fossa
Olecranon fossa
The olecranon fossa is a deep triangular depression on the posterior side of the humerus, superior to the trochlea, in which the summit of the olecranon is received during extension of the forearm.-External links: *...
of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
in extension of the forearm.
Its base is contracted where it joins the body and the narrowest part of the upper end of the ulna.
Its posterior surface, directed backward, is triangular, smooth, subcutaneous, and covered by a bursa
Bursa (anatomy)
A bursa is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of slimy fluid . It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement...
.
Its superior surface is of quadrilateral form, marked behind by a rough impression for the insertion of the Triceps brachii; and in front, near the margin, by a slight transverse groove for the attachment of part of the posterior ligament of the elbow-joint.
Its anterior surface is smooth, concave, and forms the upper part of the semilunar notch
Semilunar notch
The semilunar notch of the ulna is a large depression, formed by the olecranon and the coronoid process, and serving for articulation with the trochlea of the humerus....
.
Its borders present continuations of the groove on the margin of the superior surface; they serve for the attachment of ligaments, viz., the back part of the ulnar collateral ligament medially, and the posterior ligament laterally.
From the medial border a part of the Flexor carpi ulnaris arises; while to the lateral border the anconeus muscle
Anconeus muscle
The anconeus muscle is a small muscle on the posterior aspect of the elbow joint.Some consider anconeus to be a continuation of the triceps brachii muscle...
is attached.