Ulna - Borders

The ulna (Elbow Bone) [Figs. 1, 2] is a long bone, prismatic in form, placed at the medial side of the forearm, parallel with the radius. Ulna - Articulations. The ulna articulates with: the humerus, at the elbow as a hinge joint. the radius, near the elbow as a pivot joint, this allows the radius to cross over the ulna in pronation. the distal radius, where it fits into the ulna notch.

('proximal extremity') [Fig. 1] The upper extremity presents two curved processes, the olecranon and the coronoid process; and two concave, articular cavities, the semilunar and radial notches. Ulna - The olecranon. ('olecranon process') The olecranon is a large, thick, curved eminence, situated at the upper and back part of the ulna. 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 bas ...

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Ulna, Ulna - Articulations, Ulna - Proximal and distal aspects, Ulna - The upper extremity, Ulna - The olecranon, Ulna - The coronoid process, Ulna - The semilunar notch, Ulna - The radial notch, Ulna - The body or shaft, Ulna - Borders, Ulna - Surfaces, Ulna - The lower extremity, Ulna - Structure, Ulna - Ossification

Read more here: » Ulna: Encyclopedia II - Ulna - The upper extremity

The ulna is broader proximally, and narrower distally. Proximally, 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 ulna tuberosity to which muscles can attach. Distally (near the hand), there is a styloid process. See also:

Ulna, Ulna - Articulations, Ulna - Proximal and distal aspects, Ulna - The upper extremity, Ulna - The olecranon, Ulna - The coronoid process, Ulna - The semilunar notch, Ulna - The radial notch, Ulna - The body or shaft, Ulna - Borders, Ulna - Surfaces, Ulna - The lower extremity, Ulna - Structure, Ulna - Ossification

Read more here: » Ulna: Encyclopedia II - Ulna - Proximal and distal aspects

('corpus ulnæ') The body at its upper part is prismatic in form, and curved so as to be convex behind and lateralward; its central part is straight; its lower part is rounded, smooth, and bent a little lateralward. It tapers gradually from above downward, and has three borders and three surfaces. Ulna - Borders. The volar border (margo volaris; anterior border) begins above at the prominent medial angle of the coronoid process, and ends below in front of the styloid process. Its upper part, ...

See also:

Ulna, Ulna - Articulations, Ulna - Proximal and distal aspects, Ulna - The upper extremity, Ulna - The olecranon, Ulna - The coronoid process, Ulna - The semilunar notch, Ulna - The radial notch, Ulna - The body or shaft, Ulna - Borders, Ulna - Surfaces, Ulna - The lower extremity, Ulna - Structure, Ulna - Ossification

Read more here: » Ulna: Encyclopedia II - Ulna - The body or shaft