• Origin

Posterior surface of the distal third of the ulna.
Interosseous membrane (adjacent portion).

• Insertion

Extensor expansion of the second digit (index finger) on the dorsal aspect.

• Agonist(s)

- Extensor digitorum (synergist in index finger extension),

- Extensor pollicis longus (synergist in wrist extension),

- Lumbricals (assist in finger extension at the interphalangeal joints).

• Antagonist(s)

- Flexor digitorum superficialis,

- Flexor digitorum profundus,

- Flexor pollicis longus (in thumb-related wrist actions).

• Function

Extends the index finger independently of other digits.
Assists in extending the hand at the wrist.
Enables isolated pointing and fine finger control.

TRIGGER POINT(S)

• Location

Trigger points are usually located in the distal third of the posterior forearm, medial to the belly of the extensor digitorum, near the ulna.

• Pain Referral Pattern

Pain typically refers to the dorsal surface of the hand, focused around the second metacarpal and index finger.

Referral may feel like stiffness, aching, or soreness during typing or pointing movements.

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Potential Causes

• Overuse of the index finger (e.g., repetitive mouse clicking, texting, or typing).

• Precision tasks requiring isolated finger movement (e.g., playing instruments, sewing).

• Sustained gripping or pinching with finger extension.

• Compensatory overuse due to weakness in adjacent finger extensors.

• Inflammation in the extensor retinaculum or tendon sheaths.

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Prevention Tips

• Incorporate breaks and finger stretches during repetitive hand tasks.

• Strengthen intrinsic hand and finger extensors for stability and control.

• Maintain ergonomic wrist and hand positioning during keyboard/mouse use.

• Avoid sustained or forceful isolated index finger actions.

• Use proper hand posture and wrist support when playing instruments or working with tools.