What is the ulna and where is it located?

The ulna is the medial bone of the forearm, running from the elbow to the wrist. It acts as a stabilizing bone, articulating with the humerus at the elbow and the radius along the forearm.

What are the main features of the ulna?

The ulna has three key parts: the upper end with the olecranon and coronoid processes, the tapering shaft with borders like the interosseous border, and the lower end with a head and styloid process that connects to the radius and wrist.

Which muscles attach to the ulna?

Key muscle attachments include the olecranon for triceps brachii and flexor carpi ulnaris, the coronoid process for brachialis and flexor digitorum superficialis, and the posterior surface for anconeus and extensor pollicis longus.

How do you determine the side of an isolated ulna?

To determine the side, hold it vertically with the olecranon facing up, ensure the interosseous border faces laterally, and the trochlear notch concavity faces forward.

How does the ulna ossify?

Ossification occurs in stages: the shaft ossifies in the 8th week of fetal development, the upper end starts at 9 years and fuses by 18 years, and the lower end appears at 6 years and fuses by 20 years.

What joints does the ulna form?

The ulna forms joints with the humerus at the elbow via the trochlear notch and with the radius at both the proximal and distal radio-ulnar joints.

What is the function of the ulna in the forearm?

The ulna primarily provides stability to the forearm, especially at the elbow, and supports muscle attachments for forearm and hand movements. It also articulates with the radius to allow rotation of the forearm.

Ulna Anatomy – Olecranon, Trochlear Notch & Elbow Joint

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