Muscle:Brachioradialis
Brachioradialis is a long, superficial muscle of the radial forearm bridging the elbow joint, running from the lateral supracondylar ridge of the humerus to the radial styloid. It is primarily an elbow flexor and functions as a shunt muscle, stabilising the elbow against centrifugal distraction during rapid movement rather than accelerating it. Trigger points (TrPs) in the brachioradialis are a common cause of lateral epicondylar pain and dorsal thumb-web pain, frequently misattributed to tennis elbow, C5–6 radiculopathy, or de Quervain's tenosynovitis. The muscle is almost always involved as part of the extensor mass functional unit and rarely presents in isolation; it is most consistently co-involved with the Muscle:Supinator and Extensor Carpi Radialis Longus.
Anatomy
- Proximal attachment: Lateral supracondylar ridge of the humerus and lateral intermuscular septum, distal to where the radial nerve penetrates the septum at mid-arm level
- Distal attachment: Styloid process of the radius; variable slips may attach to the scaphoid, navicular, and third metacarpal
- Fibre architecture: Exceptionally long fibres (121 mm — roughly twice the length of other forearm muscles); fibre-length-to-muscle-length ratio of 0.69, producing a roughly transverse endplate zone across the midbelly. Designed for speed and range of motion rather than force.
- Innervation: Radial nerve, posterior cord, upper trunk; spinal nerves C5 and C6
- Primary actions: Flexion of the forearm at the elbow, particularly during rapid or loaded movement; returns the forearm from either full pronation or full supination to the neutral (mid) position when these movements are resisted. As a shunt muscle, its line of pull stabilises the elbow joint against centrifugal distraction — contrasted with the biceps brachii and brachialis ("spurt muscles") which accelerate elbow movement.
The superficial (sensory) branch of the radial nerve passes between the brachioradialis and the underlying extensor carpi radialis longus. This anatomical relationship is clinically relevant during TrP injection (see Trigger Point Injection).
Referred Pain Pattern
The essential pain pattern projects to:
- Lateral epicondyle — causes the epicondyle to become tender to light tapping at its distal face
- Dorsal aspect of the web space between the thumb and index finger
A spillover pattern extends along the radial dorsal forearm over the length of the muscle.
Pain referred to the lateral epicondyle from brachioradialis TrPs concentrates at the distal half of the epicondyle. Tenderness predominantly at the proximal half of the epicondyle suggests Muscle:Triceps_Brachii TrP₂ as the source rather than brachioradialis.
Experimental injection of hypertonic saline into latent brachioradialis TrPs produced referred pain to the dorsum of the wrist in 35% of cases and local pain in 100% of cases; the local pain area was approximately twice the area of referred pain.
Activation and Perpetuating Factors
TrPs are activated by:
- Repetitive forceful handgrip, especially with ulnar deviation of the wrist — the larger the object grasped and the greater the ulnar deviation, the greater the overload
- Combined gripping and forearm rotation: turning doorknobs, using screwdrivers, wringing cloths
- Digging with a trowel or garden implement
- Prolonged handshaking
- One-hand tennis backhand with a dropped racquet head
- Canoeing, particularly in the non-dominant forearm
- Scraping ice from a windshield
Satellite TrP relationships: Key TrPs in the scalene muscles can induce satellite TrPs in the brachioradialis. The usual sequence in which the lateral epicondylar muscles develop TrPs is: (1) supinator, (2) brachioradialis, (3) extensor carpi radialis longus, (4) extensor digitorum, (5) triceps brachii, (6) anconeus, (7) biceps and brachialis together.
The brachioradialis rarely involves without the supinator; involvement of either typically draws in the other. Isolated brachioradialis involvement without supinator is unusual.
Clinical Examination
Occupational and Activity History
Establish the activity pattern responsible. The typical history includes repetitive grip-and-rotate tasks or racquet sports. The pathognomonic complaint is objects unexpectedly slipping from the hand — grip failure at the moment of load, particularly when pouring liquids or tipping a cup to drink. Ask specifically about activities combining forearm rotation with grip; these are the most reliable activators and distinguish brachioradialis-pattern weakness from pure flexor or extensor problems.
Active Range of Motion
Test elbow and wrist ROM in all planes. The stretch position of the brachioradialis is full elbow extension with forearm pronation. Restriction or pain at this position indicates TrP tension. Grip strength is typically reduced, and is dramatically impaired when tested with the wrist in ulnar deviation.
Handgrip Test
This is the key functional test for the entire extensor mass:
- Patient positions hand in extension with radial deviation (normal handshake position)
- Patient squeezes the examiner's hand
Positive: Pain provoked when gripping with wrist extended (extensors in shortened position). Grasping with the wrist flexed also causes pain but produces even greater weakness — the grip is reflexly inhibited by TrP activity in the simultaneously contracting extensors.
Confirm TrP origin with the Compression Test: apply strong wide pincer compression to the extensor mass below the elbow while repeating the Handgrip Test. Compression eliminates the pain response; release of pressure restores it.
Trigger Point Examination
The patient sits with the forearm on a padded armrest, elbow slightly flexed.
- Identify the muscle by having the patient flex the forearm against resistance with the elbow at 90° — the brachioradialis stands out prominently
- Apply pincer palpation — encircle the muscle between thumb and fingers, separating it from the underlying extensor carpi radialis longus and brevis
- TrPs are found in the deep part of the muscle, approximately 2 cm distal to the antecubital crease
- Compression of active TrPs reproduces the characteristic referred pain to the dorsal thumb-web
For the four diagnostic criteria used to confirm a TrP (taut band, spot tenderness, referred pain, patient recognition), see Concept:Trigger_Point.
Palpation distinction: The brachioradialis immediately overlies the ECRL. An LTR from the brachioradialis causes radial deviation and slight wrist extension; an LTR from the underlying ECRL causes strong radial abduction with some extension. When referred pain to the base of the thumb is produced by deep palpation in the proximal forearm, the source may be brachioradialis or the underlying supinator — both must be considered.
Epicondyle Tapping Test
Tap the lateral epicondyle lightly with a fingertip:
- Distal half tenderness → referred tenderness from brachioradialis, ECRL, or supinator TrPs (all attach directly or via fascia to the lateral epicondyle)
- Proximal half tenderness → referred tenderness from triceps brachii TrPs (TrP₂)
Following TrP inactivation, this test should no longer produce referred tenderness.
Joint Play Assessment
Assess joint play at the elbow (humeroulnar, radiohumeral, proximal radioulnar articulations) and wrist (distal radioulnar, radiocarpal, intercarpal). If any articulation crossed by the brachioradialis lacks normal joint play, TrP treatment alone will not produce lasting symptom relief.
Differential Diagnosis
| Condition | Must be present | Must be absent | Merely possible |
|---|---|---|---|
| Brachioradialis TrPs | Taut band with spot tenderness in brachioradialis belly; referred pain to lateral epicondyle and/or dorsal thumb-web; Handgrip Test positive; pain eliminated by extensor mass Compression Test | Neurological deficit (motor weakness, dermatomal sensory loss, reflex change) | Lateral epicondylar tenderness; grip weakness; radial forearm aching |
| Lateral epicondylitis | Localised tenderness directly at the lateral epicondyle and common extensor tendon origin; pain reproduced by resisted wrist extension at the enthesis | TrP in extensor mass whose compression eliminates the epicondylar pain | Dorsal hand and wrist pain; grip weakness |
| C5–6 radiculopathy | Dermatomal sensory change in C6 distribution (thumb, index finger, radial forearm); diminished brachioradialis deep tendon reflex; positive Spurling's test | Reproduction of epicondylar or thumb-web pain by extensor mass TrP compression | Lateral epicondylar pain; grip weakness |
| De Quervain's tenosynovitis | Positive Finkelstein test (ulnar deviation with thumb in fist reproduces pain); tenderness localised over the radial styloid and first extensor compartment | Brachioradialis TrP whose compression reproduces the base-of-thumb pain | Dorsal thumb-web pain; pain with grip |
| Carpal tunnel syndrome | Positive Phalen's test (≥60 seconds wrist flexion reproduces symptoms); nocturnal paraesthesiae in median nerve distribution; Tinel's sign at carpal tunnel | Extensor mass TrP pattern; no motor or sensory deficit consistent with median nerve | Wrist and hand pain; grip weakness |
| Radial tunnel syndrome | Maximum tenderness approximately 3–4 cm distal to the lateral epicondyle over the radial tunnel; pain reproduced by resisted supination and resisted middle finger extension | Motor or sensory deficit of radial nerve distribution | Lateral epicondylar aching; radial forearm pain |
Brachioradialis TrPs and lateral epicondylitis, C5–6 radiculopathy, or de Quervain's tenosynovitis can coexist. Symptoms will persist until the TrP component is specifically addressed. Electrodiagnostic testing and clinical TrP examination together establish the composite diagnosis.
Associated articular dysfunctions: volar subluxation of carpal bones; distal radioulnar joint dysfunction.
Treatment
Spray and Stretch
- Patient seated, forearm extended at the elbow and resting on a padded support, elbow resting on the support
- Operator holds the patient's fingers (not the hand), exposing the referred pain zone
- Primary stretch: full elbow extension — this is the dominant movement for releasing the brachioradialis
- Additional stretch: forearm pronation (moves proximal and distal attachments farther apart beyond elbow extension alone)
- Vapocoolant applied proximal-to-distal, detouring to cover the lateral epicondyle, then continuing over the dorsum of the hand and dorsal web between thumb and index finger
- TrP pressure release may be applied simultaneously during the stretch
Postisometric relaxation: Examiner resists gentle elbow flexion while the patient inhales; on slow exhalation, the elbow is passively extended further. Repeat for 3 cycles, applying moist heat between cycles.
For general principles of TrP treatment see Concept:Apropos_Treatment.
Trigger Point Injection
Patient supine, forearm supported slightly flexed at the elbow and pronated.
- TrP held in pincer grasp between finger and thumb, or located by flat palpation
- Needle must reach the deepest fibres — superficial injection misses the TrP; the endplate zone runs transversely across the midbelly
- When referred pain is evoked in the base of the thumb by a deep proximal injection, the TrP may be in the brachioradialis or the underlying supinator — probe both depths
- Pre-procedure warning: the sensory branch of the radial nerve passes between this muscle and the ECRL and may be transiently anaesthetised; warn the patient to expect temporary numbness over the dorsal thumb and hand
After injection: spray and stretch → hot pack → slow active full ROM × 3.
For general injection principles see Concept:Trigger_Point_Injection.
Patient Education
- Avoid activities combining grip with forearm rotation (screwdrivers, trowels, doorknobs) until TrPs are fully inactive
- When playing tennis: keep the racquet head angled upward — a dropped head is the classic activating position
- Pour liquids by rotating from the shoulder, not by ulnarly deviating the wrist
- A wrist support brace limiting hand flexion and ulnar deviation protects the muscle during recovery and is particularly important for unavoidable activities (see corrective actions in the source chapter)
- Self-stretch: place the affected elbow on a support, laterally rotate the arm at the shoulder so the antecubital fossa faces upward; use the other hand to pronate the forearm and extend the elbow — this passively achieves the full stretch position
Satellite Trigger Points
TrPs in the brachioradialis commonly develop secondary to key TrPs in:
- Muscle:Supinator — the most common key TrP relationship; treat supinator first when both are involved
- Extensor Carpi Radialis Longus — closely associated; the two muscles are nearly inseparable by palpation
- Scalene muscles — key TrPs in the scalenes induce satellite TrPs in the brachioradialis
Once brachioradialis TrPs are established, involvement typically spreads to:
- Muscle:Extensor_Digitorum — long finger extensors, especially middle and ring fingers
- Muscle:Triceps_Brachii — distal lateral end of the medial head, proximal to the lateral epicondyle
Related Pages
- Muscle:Extensor_Carpi_Radialis — almost always co-involved; examine together
- Muscle:Extensor_Carpi_Ulnaris — part of the extensor mass; examine if ulnar wrist pain is present
- Muscle:Supinator — most common key TrP source for brachioradialis satellite involvement; covers radial nerve entrapment in detail
- Muscle:Extensor_Digitorum — next muscle recruited as the spread pattern progresses
- Concept:Trigger_Point — diagnostic criteria, LTR, taut band, contraction knot, and integrated hypothesis
- Concept:Apropos_Treatment — general principles of TrP treatment including spray and stretch technique
- Concept:Trigger_Point_Injection — injection principles and post-injection protocol
References
- Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual, Volume 1: The Upper Half of Body. 2nd ed. Baltimore: Williams & Wilkins; 1999. Chapter 34.