What is brachioradialis?

Brachioradialis Muscle: Anatomy, Function, and Clinical Relevance

Introduction

The brachioradialis is a prominent superficial muscle of the forearm that plays a crucial role in elbow flexion, especially when the forearm is in a neutral position. Although it's anatomically located in the posterior (extensor) compartment of the forearm, functionally it behaves like a flexor. Due to its distinct position and function, it is often referred to as the "beer-drinking muscle" because of its engagement in mid-pronated elbow flexion.

Understanding the brachioradialis is important for clinicians, physiotherapists, and students involved in rehabilitation, injury prevention, and muscle performance evaluation.

Anatomy of the Brachioradialis

Origin

Insertion

Nerve Supply

  • Radial nerve (C5, C6, C7)
    (Despite being a flexor, it is innervated by the radial nerve, which typically supplies extensors.)

Blood Supply

  • Radial recurrent artery

Function

The primary function of the brachioradialis is

  • Elbow flexion when the forearm is in a mid-pronated (neutral) position.

Additional functional roles:

  • Stabilizes the elbow joint during rapid movements.

  • Assists in pronation or supination to return the forearm to a neutral position.

Clinical Assessment of Brachioradialis

1. Palpation

  • Position the patient with the elbow flexed to 90° and the forearm in neutral.

  • Ask the patient to flex their elbow against resistance.

  • The muscle belly becomes prominent on the lateral forearm, just distal to the elbow.

2. Manual Muscle Testing (Power)

  • Position: Patient seated, elbow flexed to 90°, forearm in neutral (thumb up).

  • Procedure: Apply resistance at the distal forearm while the patient flexes the elbow.

  • Grading: Follows the standard MMT scale (0 to 5)

3. Muscle Length Test

  • Rarely assessed for length due to its functional short range.

  • Stretch by extending the elbow with the forearm in full pronation and wrist flexion.

Exercises for Strengthening and Rehabilitation

1. Dumbbell Hammer Curls

  • Patient Position: Seated or standing, holding dumbbells in a neutral grip (thumbs up).

  • Procedure: Flex the elbow from full extension to about 120°, then lower slowly.

  • Repetitions: 2–3 sets of 10–15 reps.

2. Resistance Band Elbow Flexion (Neutral)

  • Position: Arm at the side, forearm in neutral.

  • Procedure: Pull the band upward by flexing the elbow while maintaining the neutral position.

  • Goal: Improve strength and endurance.

3. Eccentric Lowering

  • Position: Start with elbow flexed, forearm in neutral.

  • Procedure: Slowly lower a dumbbell to extend the elbow over 4–5 seconds.

  • Use: Helpful in tendon rehabilitation.

Trigger Points and Referred Pain

Common Trigger Point Locations

  • In the proximal third of the muscle belly, near the elbow.

Referred Pain Pattern

  • Pain radiates down the lateral forearm toward the wrist and sometimes the thumb base.

  • May be mistaken for lateral epicondylitis or radial nerve irritation.

Treatment for Trigger Points

Common Injuries and Clinical Conditions

1. Brachioradialis Strain

  • Caused by overuse, especially in repetitive hammering or lifting.

  • Symptoms: Local tenderness, swelling, and pain during elbow flexion.

2. Radial Tunnel Syndrome

  • Although the radial nerve innervates the muscle, it's rarely involved unless compression occurs.

  • May result in weakness or altered sensation.

3. Tendinopathy

  • Rare, but can occur with chronic overuse in activities involving grip or load lifting in a neutral forearm position.

FAQs

Q1: Is brachioradialis a flexor or extensor?

Answer: Functionally it is a flexor, but anatomically it lies in the extensor compartment and is innervated by the radial nerve.

Q2: How to differentiate brachioradialis pain from tennis elbow?

Answer: Pain from brachioradialis is felt more in the muscle belly, while tennis elbow (lateral epicondylitis) pain is localized at the lateral epicondyle.

Q3: Can brachioradialis be isolated in exercises?

Answer: It’s difficult to isolate, but hammer curls emphasize its activation better than other elbow flexors.

Q4: What happens if the radial nerve is injured?

Answer: Depending on the level of injury, brachioradialis may weaken, especially elbow flexion in a neutral position.

References

  1. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2013). Clinically Oriented Anatomy (7th Ed.). Lippincott Williams & Wilkins.
    https://shop.lww.com/Clinically-Oriented-Anatomy/p/9781451119459

  2. Physiopedia. Brachioradialis Muscle.
    https://www.physio-pedia.com/Brachioradialis

  3. Kenhub. Brachioradialis: Origin, Insertion, and Function.
    https://www.kenhub.com/en/library/anatomy/brachioradialis

  4. Travell, J. G., & Simons, D. G. (1999). Myofascial Pain and Dysfunction: The Trigger Point Manual.
    https://www.wolterskluwer.com/en/solutions/ovid/myofascial-pain-and-dysfunction-the-trigger-point-manual-vol-1-1498

  5. TeachMeAnatomy. Brachioradialis Muscle.
    https://teachmeanatomy.info/upper-limb/muscles/brachioradialis/


Location: Pakistan

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