Radius and Ulna

In the human body, the forearm consists of the radius and which other bone?

And the answer: ulna.      

The forearm is made up of two bones, the ulna and the radius, both of which extend from your elbow to your wrist. The ulna is located on the pinky side of your arm, while the radius is on your thumb side.

Photo credit: Athikhun.suw.

Sing with us now: "The chest bone's connected to the ... arm bones!" The humerus, to be exact. The human arm is made from three long bones – the humerus, radius, and ulna – that are linked at the elbow by a hinge joint. The radius and ulna, connecting to opposite ends of your hand, work together to create the wrist (formally known as the carpus). The wrist itself is quite an important joint, as major arteries come closer to the surface than any other place in your body. For this reason, the wrist is the best place to check your pulse.

With the help of the humerus bone, the radius and ulna also create the elbow joint. Due to their helpful mobility and lightweight nature, the radius and ulna tend to suffer fractures and breaks more than many other larger bones in the body. However, they are still capable of bearing weight. The radius and ulna work together to provide leverage for lifting and rotation for manipulation of objects (you can thank your radius and ulna for your fast typing abilities). When babies start crawling, the radius also can help to provide mobility and support for the rest of their growing bones.

In animals, the radius and ulna can actually be weight-bearing bones. In four-legged animals, the radius supports weight while the ulna helps with joint mobility. In horses and oxen, the radius passes straight down the forearm to expand at the wrist, while in dogs, the radius passes diagonally from the elbow joint to the foot.

Learn more about the physiology of the radius and ulna below.

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