Brachioradialis: origin, insertion, action and innervation
The brachioradialis arises from the lateral supracondylar ridge of the humerus and inserts just above the styloid process of the radius. It flexes the elbow, most strongly in mid-pronation, and is supplied by the radial nerve.
Quick answer
- Latin name
- Musculus brachioradialis
- Origin
- Upper two thirds of the lateral supracondylar ridge of the humerus
- Insertion
- Lateral side of the distal radius, just above the radial styloid process
- Action
- Flexes the elbow, most strongly with the forearm half-way between pronation and supination
- Innervation
- Radial nerve (C5–C6)
- Blood supply
- Radial recurrent artery
The brachioradialis is the long muscle on the thumb side of the forearm. It's a curious one: it sits with the extensor muscles and shares their nerve, yet its main job is to flex the elbow.
Where it is
It forms the lateral border of the cubital fossa and runs down the lateral (thumb) side of the forearm, superficial to the radial nerve's branches, before becoming a flat tendon in the lower half of the forearm.
Origin and insertion
- Origin: the upper two thirds of the lateral supracondylar ridge of the humerus, above the elbow.
- Insertion: the lateral side of the distal radius, just above the styloid process.
What it does
The brachioradialis flexes the elbow, and it's strongest when the forearm is in the neutral, thumb-up position, as when you lift a mug or swing a hammer. It can also bring the forearm back to that mid-position from full pronation or supination.
Innervation and blood supply
It is supplied by the radial nerve (C5–C6), like the extensors around it, and by the radial recurrent artery.
How to remember it
- Brachio-radialis = from the arm (humerus) to the radius.
- "The beer-drinking muscle": thumb up, elbow bending.
- Radial nerve, but a flexor: the exception in the back compartment.
Frequently asked questions
What is the main action of the brachioradialis?
Flexion of the elbow, strongest in the mid-pronated (thumb-up) position.
Which nerve supplies the brachioradialis?
The radial nerve, from roots C5 and C6.
Where does the brachioradialis insert?
On the lateral side of the distal radius, just above the radial styloid process.