Espiral AtlasUlna
ulna
Study entry
Parts
Proximal: olecranon, coronoid process, trochlear notch (fits the trochlea), radial notch and ulnar tuberosity. Shaft with interosseous border and supinator crest. Distal: head of the ulna and styloid process of the ulna.
Joints
Humeroulnar and proximal and distal radioulnar; it does not touch the carpus directly (the articular disc lies between them).
Palpation
Olecranon, posterior border along its whole length, head and styloid process.
Clinical
Fracture of the olecranon is common, because it is subcutaneous and prominent: generally a fall on the elbow together with strong contraction of the triceps, which pulls the fragment backward.
Source: cap. 3, «Huesos del antebrazo» y cuadro clínico «Fractura del olécranon»
Clinical correlation
Fractures of the radius and ulna; Colles fracture
In children they are usually greenstick fractures. A direct blow breaks both bones at the same level, generally in the middle third. Because the interosseous membrane joins the two, a fracture of one bone tends to come with dislocation of the nearest joint. The Colles fracture is the most common of the forearm: a complete transverse fracture of the distal 2 cm of the radius, frequent after 50 and in women with osteoporosis, from a fall on the outstretched, pronated hand. The distal fragment (often comminuted) goes backward, the styloid process of the ulna may be torn off and, with the radius shortened, the styloid of the radius is no longer more distal than that of the ulna.
Fracture of the olecranon
It is common, because the olecranon is prominent and lies under the skin. It comes from a fall on the elbow together with a strong contraction of the triceps, which pulls the fragment backward; for that reason it is often seen as an avulsion fracture and usually calls for fixation with pins. It heals slowly, with a cast for a long time.
Related clinical cases
- Fractures of the radius and ulna; Colles fracture
- Fracture of the olecranon