Forearm muscles

Forearm Muscles

The forearm is a complex structure composed of numerous muscles that are responsible for a wide range of movements of the wrist, hand, and fingers. These muscles can be broadly categorized into two groups: the anterior (flexor) compartment and the posterior (extensor) compartment.

Anterior Compartment

The anterior compartment of the forearm contains muscles primarily responsible for flexion of the wrist and fingers, as well as pronation of the forearm. These muscles are innervated mainly by the median nerve and the ulnar nerve.

Superficial Layer

• Pronator teres: This muscle pronates the forearm and assists in flexion of the elbow.
• Flexor carpi radialis: It flexes and abducts the wrist.
• Palmaris longus: This muscle is absent in some individuals; it flexes the wrist and tenses the palmar aponeurosis.
• Flexor carpi ulnaris: It flexes and adducts the wrist.

Intermediate Layer

• Flexor digitorum superficialis: This muscle flexes the middle phalanges of the fingers.

Deep Layer

• Flexor digitorum profundus: It flexes the distal phalanges of the fingers.
• Flexor pollicis longus: This muscle flexes the thumb.
• Pronator quadratus: It pronates the forearm.

Posterior Compartment

The posterior compartment of the forearm contains muscles that extend the wrist and fingers, and supinate the forearm. These muscles are primarily innervated by the radial nerve.

Superficial Layer

• Brachioradialis: Although located in the posterior compartment, it flexes the elbow.
• Extensor carpi radialis longus: It extends and abducts the wrist.
• Extensor carpi radialis brevis: This muscle also extends and abducts the wrist.
• Extensor digitorum: It extends the fingers.
• Extensor digiti minimi: This muscle extends the little finger.
• Extensor carpi ulnaris: It extends and adducts the wrist.

Deep Layer

• Supinator: This muscle supinates the forearm.
• Abductor pollicis longus: It abducts the thumb.
• Extensor pollicis brevis: This muscle extends the proximal phalanx of the thumb.
• Extensor pollicis longus: It extends the distal phalanx of the thumb.
• Extensor indicis: This muscle extends the index finger.

Clinical Relevance

Understanding the anatomy of the forearm muscles is crucial for diagnosing and treating various conditions such as carpal tunnel syndrome, tennis elbow (lateral epicondylitis), and golfer's elbow (medial epicondylitis). Injuries to the nerves supplying these muscles can lead to significant functional impairment.

See Also

• Muscles of the upper limb
• Wrist joint
• Hand anatomy