Muscles/Forearm

Forearm

flexor pollicis longus

FLEK-sor POL-ih-sis LON-gus

Deep in the anterior forearm, flexor pollicis longus flexes the thumb's tip joint, powering thumbs-up gestures and strong grips. Vital for tools, phones, and sports requiring thumb control. Essential for fine motor strength.

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Common Pain & Injury

Deep forearm ache to thumb tip, worse with thumb flexion. Overuse in texting or tools causes strain. Doctor if numbness or weakness persists.

Anatomy & Function

Origin

Anterior radius and interosseous membrane (front of larger forearm bone)

Insertion

Distal phalanx of thumb (thumb tip)

Actions

Interphalangeal joint flexion of thumb (curling thumb tip)
Metacarpophalangeal flexion (thumb base bend)

Innervation

Anterior interosseous nerve (median)

Muscle Relationships

Antagonists

Extensor pollicis longus

Synergists

Flexor digitorum profundusAbductor pollicis brevis

Trigger Points

Deep forearm, referring to thumb tip, thenar eminence, and index finger.

Stretches

1Thumb IP extension stretch

2Prayer thumb stretch

3Forearm pronator stretch

Common Conditions

Flexor pollicis longus tendinitisAnterior interosseous nerve syndrome

Anatomical Parts

Left flexor pollicis longusRight flexor pollicis longus

FAQ

Flexor pollicis longus what does it do

Flexes thumb tip for precise grip strength.

Flexor pollicis longus pain causes

Repetitive thumb motion; strengthen and stretch forearm.

Stretch flexor pollicis longus

Extend thumb tip back while stretching wrist.

Flexor pollicis longus rupture

Rare, causes loss of thumb flexion; surgical repair often needed.

Exercises for flexor pollicis longus

20

Bottoms-Up Clean From The Hang Position position 1

Bottoms-Up Clean From The Hang Position position 2

Bottoms-Up Clean From The Hang Position

intermediate·kettlebells

Cable Wrist Curl position 1

Cable Wrist Curl position 2

Cable Wrist Curl

beginner·cable

Dumbbell Lying Pronation position 1

Dumbbell Lying Pronation position 2

Dumbbell Lying Pronation

intermediate·dumbbell

Dumbbell Lying Supination position 1

Dumbbell Lying Supination position 2

Dumbbell Lying Supination

intermediate·dumbbell

Farmer's Walk position 1

Farmer's Walk position 2

Farmer's Walk

intermediate·other

Finger Curls position 1

Finger Curls position 2

Finger Curls

beginner·barbell

Kneeling Forearm Stretch position 1

Kneeling Forearm Stretch position 2

Kneeling Forearm Stretch

Palms-Down Dumbbell Wrist Curl Over A Bench position 1

Palms-Down Dumbbell Wrist Curl Over A Bench position 2

Palms-Down Dumbbell Wrist Curl Over A Bench

beginner·dumbbell

Palms-Down Wrist Curl Over A Bench position 1

Palms-Down Wrist Curl Over A Bench position 2

Palms-Down Wrist Curl Over A Bench

beginner·barbell

Palms-Up Barbell Wrist Curl Over A Bench position 1

Palms-Up Barbell Wrist Curl Over A Bench position 2

Palms-Up Barbell Wrist Curl Over A Bench

beginner·barbell

Palms-Up Dumbbell Wrist Curl Over A Bench position 1

Palms-Up Dumbbell Wrist Curl Over A Bench position 2

Palms-Up Dumbbell Wrist Curl Over A Bench

beginner·dumbbell

Plate Pinch position 1

Plate Pinch position 2

Plate Pinch

intermediate·other

Rickshaw Carry position 1

Rickshaw Carry position 2

Rickshaw Carry

intermediate·other

Seated Dumbbell Palms-Down Wrist Curl position 1

Seated Dumbbell Palms-Down Wrist Curl position 2

Seated Dumbbell Palms-Down Wrist Curl

beginner·dumbbell

Seated Dumbbell Palms-Up Wrist Curl position 1

Seated Dumbbell Palms-Up Wrist Curl position 2

Seated Dumbbell Palms-Up Wrist Curl

beginner·dumbbell

Seated One-Arm Dumbbell Palms-Down Wrist Curl position 1

Seated One-Arm Dumbbell Palms-Down Wrist Curl position 2

Seated One-Arm Dumbbell Palms-Down Wrist Curl

intermediate·dumbbell

Seated One-Arm Dumbbell Palms-Up Wrist Curl position 1

Seated One-Arm Dumbbell Palms-Up Wrist Curl position 2

Seated One-Arm Dumbbell Palms-Up Wrist Curl

beginner·dumbbell

Seated Palm-Up Barbell Wrist Curl position 1

Seated Palm-Up Barbell Wrist Curl position 2

Seated Palm-Up Barbell Wrist Curl

beginner·barbell

Seated Palms-Down Barbell Wrist Curl position 1

Seated Palms-Down Barbell Wrist Curl position 2

Seated Palms-Down Barbell Wrist Curl

beginner·barbell

Seated Two-Arm Palms-Up Low-Pulley Wrist Curl position 1

Seated Two-Arm Palms-Up Low-Pulley Wrist Curl position 2

Seated Two-Arm Palms-Up Low-Pulley Wrist Curl

beginner·cable

Also Works flexor pollicis longus

10

Alternate Hammer Curl position 1

Alternate Hammer Curl position 2

Alternate Hammer Curl

beginner·dumbbell

Alternate Incline Dumbbell Curl position 1

Alternate Incline Dumbbell Curl position 2

Alternate Incline Dumbbell Curl

beginner·dumbbell

Alternating Hang Clean position 1

Alternating Hang Clean position 2

Alternating Hang Clean

intermediate·kettlebells

Atlas Stone Trainer position 1

Atlas Stone Trainer position 2

Atlas Stone Trainer

intermediate·other

Atlas Stones position 1

Atlas Stones position 2

Atlas Stones

Axle Deadlift position 1

Axle Deadlift position 2

Axle Deadlift

intermediate·other

Backward Drag position 1

Backward Drag position 2

Backward Drag

beginner·other

Band Assisted Pull-Up position 1

Band Assisted Pull-Up position 2

Band Assisted Pull-Up

beginner·other

Barbell Curl position 1

Barbell Curl position 2

Barbell Curl

beginner·barbell

Barbell Deadlift position 1

Barbell Deadlift position 2

Barbell Deadlift

intermediate·barbell

Related Forearm Muscles

abductor pollicis longus

This forearm muscle runs to the thumb base, abducting and extending it for radial deviation. Vital for wrist stability in lifts like deadlifts. Forearm specialists train it for grip resilience.

Tiny elbow extensor at back upper forearm, stabilizes during pressing and gripping. Aids triceps in extensions. Powerlifters note its elbow lockout role.

brachioradialis

The brachioradialis is the thick forearm muscle on the radial (thumb) side, visible in hammer curls. It flexes the elbow in neutral grip, stabilizing during pulls and carries. Builds Popeye forearms for grip strength.

extensor carpi radialis brevis

The ECRB is a forearm extensor on the radial side, extending and abducting the wrist. Mid-forearm location builds wrist stability for racquets and grips.

extensor carpi radialis longus

The ECRL is the longer radial wrist extensor, more proximal in forearm for powerful extension and abduction. Stabilizes in heavy pulls.

extensor carpi ulnaris

The ECU is the ulnar (pinky) wrist extensor in posterior forearm, balancing extension with deviation. Key for stability in sports.

extensor digiti minimi

The EDM is a thin forearm muscle specifically extending the pinky finger at knuckles and wrist. Lies ulnar to EDM, aids fine grip control.

extensor digitorum

The extensor digitorum is the central posterior forearm muscle, extending fingers 2-5 at knuckles and wrist. Fan-like tendons create dorsal hand ridges for grip extension.

Forearm Pain Guide

Common causes and relief

Activities & Sports

See which activities use flexor pollicis longus