Wrist Joint and Hand Anatomy

• The goal is to understand the wrist joint formation and its type.
• Learn the wrist joint movements.
• Know about the wrist joint's articulation with carpal bones.
• Learn about the thenar and hypothenar eminences.
• Know the muscles of the hand including origin, insertion, and nerve supply.
• Explore the function of muscles in the hand.
• Explain the movements of the thumb.
• Describe the fascial planes of the hand.

Wrist Joint

• It's a Synovial Ellipsoid articulation.
• Above:
  • Distal end of the radius
  • Articular disc
• Below:
  • Scaphoid
  • Lunate
  • Triquetral

Movement of Wrist

• Flexion is enabled by the Flexor Carpi Radialis (FCR) and Flexor Carpi Ulnaris (FCU).
• Extension is enabled by the Extensor Carpi Radialis Longus (ECRL), Extensor Carpi Radialis Brevis (ECRB), and Extensor Carpi Ulnaris (ECU).
• Adduction is enabled by the Extensor Carpi Ulnaris (ECU) and Flexor Carpi Ulnaris (FCU).
• Abduction is enabled by the Extensor Carpi Radialis Longus (ECRL), Extensor Carpi Radialis Brevis (ECRB), and Flexor Carpi Radialis (FCR).

Anatomical Snuff-Box

• It's a depression on the lateral side of the wrist, visible when the thumb is abducted and extended.
• Boundaries:
  • Anteriorly: abductor pollicis longus and extensor pollicis brevis.
  • Posteriorly: extensor pollicis longus.
  • Floor: scaphoid & trapezium
• Contains the radial artery.

Extensor Retinaculum

• It's a thickened band of deep fascia at the back of the wrist.

Flexor Retinaculum

• It is a thickened fibrous band of deep fascia in the front of the carpal bones.
• Attachments:
  • Medially: Pisiform and hamate.
  • Laterally: scaphoid and trapezium.
• Structures superficial to it:
  • Ulnar nerve
  • Ulnar artery
  • Palmar cutaneous branch of ulnar N
  • Palmaris longus tendon
  • Palmar cutaneous branch of median N
• Structures that pass deep to it:
  • Flexor digitorum superficialis
  • Flexor digitorum profundus
  • Median nerve
  • Flexor pollicis longus

Muscles of Hand

• Thenar muscles: 4
  • 3 forming thenar eminence
    • Abductor Pollicis brevis
    • Flexor Pollicis brevis
    • Opponens Pollicis
  • Adductor pollicis
• The Ulnar nerve supplies all of them except the three muscles of the thenar eminence, which are supplied by the median nerve.
• Hypothenar muscles: 3
  • 3 forming hypothenar eminence
    • Abductor digiti minimi
    • Flexor digiti minimi
    • Opponens digiti minimi

Lumbricals (4)

• Lateral 2 muscles:
  • Unipennate
  • Supplied by median N
• Medial 2 muscles:
  • Unipennate
  • Supplied by ulnar N
• Action: Writing position
  • Flexion of metacarpophalangeal joint
  • Extension of interphalangeal joint

Palmar Interossei (4)

• Nerve supply: Ulnar N
• Action: Adduction of fingers
• Writing position

Dorsal Interossei (4)

• Nerve supply: Ulnar N
• Action: Abduction of fingers
• Writing position

Carpal Tunnel Syndrome

• Compression of the Median Nerve in the carpal tunnel.
• Manifestations:
  • Burning pain, described as "pins & needles,” in the lateral 3 1/2 fingers.
  • Weakness or atrophy of the thenar muscles, leading to Ape Hand.
  • Inability to oppose the thumb.
• The condition is relieved by decompressing the tunnel by making a longitudinal incision through the flexor retinaculum.