Radius: Definition and What it is

Medically and clinically reviewed by Jonathan Lee, MD and Dylan Peterson, PT, DPT

Radius Definition and Meaning

The radius is one of the two major bones in the forearm (the other is the ulna). The radius runs from the elbow to the wrist. It plays a critical role in the motion and stability of the arm, including forearm rotation, elbow flexibility, and wrist mobility.

Anatomy of the Radius

The radius is composed of three distinct parts. The proximal radius connects to the humerus (upper arm bone) and facilitates forearm rotation. The radial shaft, or central section, is slightly curved and is responsible for supporting the forearm's weight and maintaining its shape. The distal radius forms the wrist joint and is essential for the wrist’s range of motion.

Function of the Radius

The radius plays a key role in the movement and stability of the forearm and wrist. It enables supination (turning the palm upward) and pronation (turning the palm downward) as well as the flexion and extension of the elbow and wrist. The radius also serves as an attachment point for muscles and ligaments, contributing to the forearm's strength and flexibility.

Various conditions can affect the radius, including:

  • Radial tunnel syndrome: This condition involves pain and weakness in the forearm caused by pressure on the radial nerve. It often occurs due to repetitive motion or direct trauma.

  • Osteoporosis: Bone loss can weaken the radius, making it more susceptible to fractures.

  • Tendinitis: Inflammation of the tendons around the radius, often due to strain, can lead to tendinitis.

  • Nerve Injuries: Injuries to the radial nerve can lead to pain, numbness, and weakness.

  • Osteoarthritis: Osteoarthritis in the arm can affect the joints at the ends of the radius, often leading to pain and reduced mobility at the wrist or elbow

Radius Pain: A Hinge Health Perspective

The radius bone is very resilient and designed to recover from the kinds of issues that naturally can happen in the course of everyday activities or during exercise.

If you’re reluctant to move because you think you’ll cause more damage or injury to your forearm, know this: Movement is often the fastest way to healing. As our Hinge Health care team says, movement is medicine. Movement helps rehab the radius and the muscles, tendons, and ligaments that support it by increasing blood flow and gradually improving the arm’s strength and flexibility.

Physical therapy is beneficial for many conditions and injuries involving the radius. Treatment options often include customized exercise programs to improve strength and enhance mobility. Nerve gliding exercises are often a key component, especially for conditions like radial tunnel syndrome, to help ease nerve pain in the forearm. You can see a physical therapist in person or use a program like Hinge Health to access a PT via telehealth/video visit.

How Hinge Health Can Help You 

If you have joint or muscle pain that makes it hard to move, you can get the relief you’ve been looking for with Hinge Health’s online exercise therapy program.

The best part: You don’t have to leave your home because our program is digital. That means you can easily get the care you need through our app, when and where it works for you. 

Through our program, you’ll have access to therapeutic exercises and stretches for your condition. 

Additionally, you’ll have a personal care team to guide, support, and tailor our program to you. See if you qualify for Hinge Health and confirm free coverage through your employer or benefit plan here.

This article and its contents are provided for educational and informational purposes only and do not constitute medical advice or professional services specific to you or your medical condition.


  1. Bair, M. M., & Zafar Gondal, A. (2020). Anatomy, Shoulder and Upper Limb, Forearm Radius. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK544512/ 

  2. Radius. (2010). Physiopedia. https://www.physio-pedia.com/Radius 

  3. Moradi, A., Ebrahimzadeh, M. H., & Jupiter, J. B. (2015). Radial Tunnel Syndrome, Diagnostic and Treatment Dilemma. The Archives of Bone and Joint Surgery, 3(3), 156–162. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4507067 

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