Pronunciation: /æbˈdʌktə/ · also abductor muscle /æbˈdʌktə ˈmʌs(ə)l/ · Part of speech: noun · Opposite: adductor

Definition. An abductor (or abductor muscle) is a muscle that pulls a part of the body away from the midline (median sagittal plane) of the body, or away from a neighbouring part. It is the muscle that produces the movement called abduction.

How it works. When an abductor contracts, it draws the bone it acts on outward, away from the centre line — for example, lifting the arm out to the side or moving the leg away from the other leg. Each abductor is paired functionally with an opposing adductor, which pulls the same part back toward the midline; together they balance and control the joint.

Common examples.

• Deltoid (middle fibres) — abducts the shoulder, raising the arm sideways.
• Supraspinatus — initiates the first few degrees of shoulder abduction.
• Gluteus medius and gluteus minimus — abduct the hip and stabilise the pelvis during walking.
• Abductor pollicis longus and brevis — move the thumb away from the palm.
• Dorsal interossei of the hand — spread the fingers apart.

Clinical relevance. Abductor function is routinely tested in physical examination. For instance, weakness of the hip abductors (often the gluteus medius) produces a Trendelenburg sign or a lurching gait, which can point to nerve injury, muscle weakness, or hip joint problems. Assessing abductor strength also helps guide rehabilitation after surgery or injury.

Etymology. From Latin abducere, “to lead away” (ab- = away + ducere = to lead) — the muscle leads the body part away from the midline.

⚠️ Disclaimer: This explanation is provided for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding any clinical questions or patient care decisions.