Ulnar notch
Incisura ulnaris
- Synonym: Sigmoid notch of radius
Definition
The ulnar notch of the radius (incisura ulnaris radii; Sigmoid notch), is the concave articular depression on the medial (ulnar) aspect of the distal end of the radius that receives the head of the ulna, forming the distal radioulnar joint (DRUJ).
It is a shallow, smooth concavity on the medial surface of the distal radius. Its anterior surface gradually widens toward the lateral surface of the distal radius, contributing to the base of the promontorium radii.
It articulates with the circumferential articular surface (circumferentia articularis) of the ulnar head, and this joint permits forearm pronation and supination.
References
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).
