Muscles of the hand

Muscles of the Hand

The muscles of the hand are a group of muscles located in the human hand that are responsible for the movement and dexterity of the fingers and thumb. These muscles can be categorized into two main groups: the intrinsic muscles and the extrinsic muscles.

Intrinsic Muscles

The intrinsic muscles of the hand are located within the hand itself. They are responsible for fine motor movements and include the following:

• Thenar muscles: These muscles are located at the base of the thumb and include the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis.
• Hypothenar muscles: These muscles are located at the base of the little finger and include the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi.
• Lumbrical muscles: These four muscles are located in the palm and are responsible for flexing the metacarpophalangeal joints and extending the interphalangeal joints.
• Interossei muscles: These muscles are divided into the dorsal interossei and palmar interossei. The dorsal interossei abduct the fingers, while the palmar interossei adduct the fingers.

Extrinsic Muscles

The extrinsic muscles of the hand originate in the forearm and extend into the hand. They are responsible for gross motor movements and include the following:

• Flexor digitorum superficialis: This muscle flexes the proximal interphalangeal joints of the fingers.
• Flexor digitorum profundus: This muscle flexes the distal interphalangeal joints of the fingers.
• Flexor pollicis longus: This muscle flexes the thumb.
• Extensor digitorum: This muscle extends the fingers.
• Extensor indicis: This muscle extends the index finger.
• Extensor digiti minimi: This muscle extends the little finger.
• Extensor pollicis longus: This muscle extends the thumb.
• Extensor pollicis brevis: This muscle extends the thumb.
• Abductor pollicis longus: This muscle abducts the thumb.

Function

The muscles of the hand work together to perform a wide range of movements, including flexion, extension, abduction, adduction, and opposition of the fingers and thumb. These movements are essential for various activities such as gripping, holding, and manipulating objects.

Clinical Significance

Injuries or conditions affecting the muscles of the hand can significantly impact hand function. Common conditions include carpal tunnel syndrome, Dupuytren's contracture, and trigger finger. Proper diagnosis and treatment are essential for restoring hand function and preventing long-term disability.

See Also

• Anatomy of the hand
• Carpal bones
• Metacarpal bones
• Phalanges of the hand
• Hand function
• Hand surgery