Brachioradialis
Musculus brachioradialis
Also known as: beer-raising muscle, supinator longus
A superficial muscle of the lateral forearm from the lateral supracondylar ridge to the radial styloid. Although it lies in the extensor compartment and is supplied by the radial nerve, it flexes the elbow, especially in mid-pronation.
Overview
Brachioradialis arises from the proximal two-thirds of the lateral supracondylar ridge of the humerus and inserts on the lateral side of the distal radius just above the radial styloid process. It forms the lateral border of the cubital fossa and the fleshy lateral contour of the upper forearm. In the forearm the superficial branch of the radial nerve and the radial artery run beneath it.
It belongs developmentally to the posterior (extensor) muscle mass and is supplied by the radial nerve, yet it is an elbow flexor. It works best with the forearm in the mid-prone (thumb-up) position, as when lifting a mug, which earns it the nickname "beer-raising muscle". It also returns the forearm to mid-position from full pronation or supination. It is most active in rapid movements and against resistance.
Anatomy
- Origin
Proximal two-thirds of the lateral supracondylar ridge of the humerus.
- Insertion
Lateral surface of the distal radius, just proximal to the styloid process.
- Action
Flexion of the elbow (strongest with the forearm mid-prone); semi-pronation or semi-supination to the neutral position.
- Innervation
Radial nerve (before its division).
- Nerve roots
C5–C6
- Arterial supply
Radial recurrent artery and radial artery; radial collateral artery.
- Relations
Forms the lateral boundary of the cubital fossa. The radial nerve lies between it and brachialis. The radial artery and the superficial radial nerve run under it in the forearm.
Function
- Flexes the elbow, especially in the mid-prone position
- Returns the forearm to mid-position from pronation or supination
Clinical significance
Brachioradialis reflex
Tapping the distal radius produces elbow flexion (C5–C6, radial nerve). An inverted supinator reflex (finger flexion with no brachioradialis response) indicates a C5–C6 cord lesion.
Deforming force in radius fractures
In distal radius fractures, brachioradialis pulls the distal fragment proximally and radially, contributing to shortening.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.