Olecranon

The olecranon (/oʊˈlɛkrənɒn/, from Greek olene 'elbow' and kranon 'head') is a large, thick, curved bony process on the top back part of the ulna. The ulna is one of the two bones in your lower arm. The olecranon is what makes up the pointy part of your elbow that you can feel when you bend your arm.

It sits opposite to the cubital fossa, also known as the elbow pit or trochlear notch, which is the soft area on the front side of your elbow. The olecranon acts like a lever for the extensor muscles. These muscles help to straighten your elbow joint, making it easier for you to push things away or lift your arm up.

Because of its position and shape, the olecranon protects the joint behind it and helps give the elbow strength and movement. It’s an important part of how our arms work every day.

Structure

The olecranon is located at the top end of the ulna, one of the two bones in the forearm. When your hand faces forward (supination), the olecranon points toward your back (posteriorly).

It curves forward at the top, forming a noticeable edge that fits into the olecranon fossa of the humerus when you straighten your arm.

Clinical significance

Fractures of the olecranon are common injuries. When the radial head moves forward, this specific type of fracture is known as a Hume fracture.

Etymology

The word "olecranon" comes from the Greek words olene, meaning elbow, and kranon, meaning head.

Additional images

[Upper extremity](/wiki/Upper_extremity_of_ulna) of left [ulna](/wiki/Ulna). [Lateral aspect](/wiki/Lateral_\(anatomy\))

Bones of left forearm. Anterior aspect.

Plan of ossification of the ulna. From three centers.

Left elbow-joint, showing anterior and ulnar collateral ligaments.

Capsule of elbow-joint (distended). Posterior aspect.