Anatomy of the Hand & Wrist

Question 1

What are the muscles of the flexor compartment of the forearm?

Answer 1

Superficial Layer:

• Pronator Teres (Median Nerve)
• Palmaris Longus (Median Nerve)
• Flexor Carpi Ulnaris (Ulnar Nerve)
• Flexor Carpi Radialis (Median Nerve)

Intermediate Layer:

• Flexor Digitorum Superficialis (Median Nerve)

Deep Layer:

• Flexor Digitorum Profundus (Little + ring fingers = Ulnar nerve, Middle and Index fingers = Median nerve)
• Flexor Pollicis Longus (Median Nerve)
• Pronator Quadratus (Median Nerve)

Question 2

What are the muscles that extend the forearm and what is their innervation?

Answer 2

Superficial Layer:

• Brachioradialis (Radial Nerve)
• Extensor Carpi Longus (Radial Nerve)
• Extensor Carpi Brevis (Radial Nerve)
• Extensor Digitorum (Radial Nerve)
• Extensor Digiti Minimi (Radial Nerve)
• Extensor Carpi Ulnaris (Radial Nerve)
• Anconeus (Radial Nerve)

Deep Layer:

• Supinator
• Abductor Pollicis Longus
• Extensor Pollicis Longus
• Extensor Pollicis Brevis
• Extensor Indicis

Question 3

What are the muscles that control movement of the thumb and what is their innervation?

Answer 3

Thenar Muscles:

• Opponens Pollicis (Median nerve)
• Abductor Pollicis Brevis (Median nerve)
• Flexor Pollicis Brevis (Median nerve)

Question 4

What are the muscles that control movements of the little finger and what is their innervation?

Answer 4

Hypothenar Muscles:

• Opponens Digiti Minimi (Ulnar nerve)
• Abductor Digiti Minimi (Ulnar nerve)
• Flexor Digiti Minimi Brevis (Ulnar nerve)

Question 5

What are the muscles that control flexion at MCP joints and extension at IP joints of each of the fingers and what is their innervation?

Answer 5

4 Lumbricals

• Lateral 2 lumbricals (index and middle finger) innervated by Median nerve
• Median 2 lumbricals (little finger and ring finger innervated by Ulnar nerve)

Question 6

What are the muscles that control abduction and adduction of the fingers and what is their innervation?

Answer 6

• 3 Palmar Interossei (Ulnar nerve)
• 4 Dorsal Interossei (Ulnar nerve)

Question 7

What are the common conditions caused by damage to nerves in the forearm and hand?

Answer 7

Wrist drop - Radial nerve damage occuring proximal to the elbow results in un-opposed flexion of the wrist

Carpal Tunnel Syndrome - Compression of the Median nerve within the carpal tunnel

Cubital Tunnel Syndrome - Compression of the Ulnar nerve within the Cubital Tunnel