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The olecranon fossa is a deep triangular depression on the posterior side of the humerus, superior to the trochlea. It provides space for the olecranon of the ulna during extension of the forearm .
The olecranon is situated at the proximal end of the ulna, one of the two bones in the forearm. [1] When the hand faces forward 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 during extension of the forearm. [2] [3]
Close to the elbow, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus. This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is also a radial notch for the head of the radius, and the ulnar tuberosity to which muscles attach.
The coronoid fossa is the medial hollow part on the anterior surface of the distal humerus. The coronoid fossa is smaller than the olecranon fossa and receives the coronoid process of the ulna during maximum flexion of the elbow. Coronoid fossa of the humerus. Above the front part of the capitulum is a slight depression, the radial fossa, which ...
The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the medial epicondyles of the humerus. The elbow joint is a hinge joint between the arm and the forearm ; [ 2 ] more specifically between the humerus in the upper arm and the radius and ulna in the ...
The trochlear notch (/ ˈ t r ɒ k l ɪər /), [1] also known as semilunar notch and greater sigmoid cavity, is a large depression in the upper extremity of the ulna that fits the trochlea of the humerus (the bone directly above the ulna in the arm) as part of the elbow joint. It is formed by the olecranon and the coronoid process.
It is directly inferior to the coronoid fossa anteriorly and to the olecranon fossa posteriorly. In humans, these two fossae, the most prominent in the humerus, are occasionally transformed into a hole, the supratrochlear foramen, [2] which is regularly present in, for example, dogs.
The accurate adaptation of the trochlea of the humerus, with its prominences and depressions, to the trochlear notch of the ulna, prevents any lateral movement. Flexion in the humeroulnar joint is produced by the action of the biceps brachii and brachialis , [ 3 ] assisted by the brachioradialis , with a tiny contribution from the muscles ...