Muscles of the thumb

Muscles of the Thumb

The thumb is a unique digit of the human hand that is powered by a group of muscles. These muscles allow the thumb to perform a wide range of movements, including flexion, extension, abduction, adduction, and opposition. The muscles of the thumb can be categorized into two groups: the extrinsic and intrinsic muscles.

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Muscles of the thumb

Extrinsic Muscles

The extrinsic muscles of the thumb are located in the forearm and they control the gross movements of the thumb. They include:

• Flexor pollicis longus: This muscle flexes the thumb at all joints.
• Extensor pollicis brevis and Extensor pollicis longus: These muscles extend the thumb at all joints.
• Abductor pollicis longus: This muscle abducts and extends the thumb.

Intrinsic Muscles

The intrinsic muscles of the thumb are located within the hand and they control the fine movements of the thumb. They include:

• Adductor pollicis: This muscle adducts the thumb.
• Flexor pollicis brevis: This muscle flexes the thumb at the metacarpophalangeal joint.
• Opponens pollicis: This muscle opposes the thumb, bringing it across the palm to touch the other fingers.
• Abductor pollicis brevis: This muscle abducts the thumb at the carpometacarpal joint.

Function

The muscles of the thumb allow it to move in ways that enable a variety of functions, such as grasping objects, manipulating tools, and performing precise movements. The thumb's unique range of motion is largely due to the combined actions of these muscles.

Clinical Significance

Injuries or conditions that affect the muscles of the thumb can significantly impact hand function. Conditions such as carpal tunnel syndrome, thumb arthritis, and trigger thumb can cause pain, weakness, and limited mobility in the thumb.

See Also

• Hand
• Finger
• Muscular system