What is the discus triangularis?
The discus triangularis is a cartilage disc embedded between the first row of carpal bones and the ulna and radius. It ensures that forces acting on the wrist can be better absorbed and also prevents the ulna, radius and carpal bones from rubbing directly against each other.
Anatomy
When viewed from above on the back of the hand, the discus triangularis is located in the area of the outer wrist (towards the little finger side), between ulna and the first row of carpal bones. In addition, it radiates with a small portion into the gap between ulna and radius. The name triangularis comes from its triangular shape.
The position describes the synonym “Discus ulnocarpalis” better. The discus triangularis is attached to the lower edge of the radius pointing to the ulna and moves from there to the outer edge of the ulna, where it fills the joint gap between the carpal bone and ulna together with the meniscus ulnocarpalis. Up, down and outside, the disc is also secured with ligaments that run from ulna and radius to the carpal bones, thus securing the disc in position. Find more about the topic: Wrist
Function of the discus triangularis
The function of the discus triangularis can be roughly compared to that of an intervertebral disc. Since it consists of firm but nevertheless elastic cartilage, it serves as a kind of shock absorber. Without this cartilage disc, supporting movements that we make with our palms would be transferred unhindered from the hand to the forearm bones – radius and especially the ulna – without the disc.
Due to the direct bone contact, this would be very unpleasant to painful and would lead much more easily to bone fractures in the area of the forearm bones. In addition, the discus triangularis serves to improve the movability of ulna and carpal bone, as well as ulna and radius against each other. It therefore also fulfils a sliding bearing function.
