Courtesy: Dr Jean Jose MD, Associate Chief, Musculoskeletal Radiology Section, Associate Professor of Clinical Radiology, University of Miami School of Medicine, Florida, USA

 

MRI Anatomy of the Wrist

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Overview

The wrist is a complex anatomical region consisting of:

• Multiple bones
• Tendons
• Ligaments
• Neurovascular structures

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Clinical Importance

MRI of the wrist is essential for evaluating:

• Ligament injuries
• Tendon pathology
• Carpal instability

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Main Components

• Extensor tendons (dorsal)
• Flexor tendons (volar/palmar)
• Carpal bones
• Intrinsic and extrinsic ligaments

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Dorsal (Extensor) Tendon Compartments

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Key Landmark

• Lister’s tubercle (distal radius)

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Six Dorsal Compartments

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Clinical Point

• EPL crosses over:
  • Lister’s tubercle
  • Second compartment tendons

 Can lead to Intersection Syndrome

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Volar (Flexor) Tendons

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Carpal Tunnel Contents

Total: 9 Tendons

• Flexor digitorum profundus (4)
• Flexor digitorum superficialis (4)
• Flexor pollicis longus (1)

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Nerve in Carpal Tunnel

• Median nerve

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Position

• Lies between:
  • FDS and FDP tendons

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Important Note

• Flexor carpi radialis:
  • Runs in a separate canal
  • Not part of carpal tunnel

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Order (Lateral — Medial)

1. Flexor carpi radialis
2. Flexor pollicis longus
3. Flexor digitorum superficialis
4. Flexor digitorum profundus
5. Flexor carpi ulnaris

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Important Nerves of the Wrist

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Median Nerve

• Passes through carpal tunnel
• Supplies most flexor muscles

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Ulnar Nerve

• Passes through Guyon’s canal
• Located near pisiform

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Radial Nerve (Superficial Branch)

• Near radial styloid
• Supplies sensation to:
  • Thumb
  • Index finger

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Important Arteries

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Radial Artery

• Runs along volar radial side
• Passes deep to first dorsal compartment

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Ulnar Artery

• Travels with ulnar nerve in:
  • Guyon’s canal

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Carpal Bones

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Total: 8 Bones

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Proximal Row

• Scaphoid
• Lunate
• Triquetrum
• Pisiform

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Distal Row

• Trapezium
• Trapezoid
• Capitate
• Hamate

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Hook of Hamate

• Clinically important in:
  • Ulnar nerve compression
  • Sports injuries

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Wrist Joints

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Radiocarpal Joint

• Radius + Scaphoid + Lunate

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Distal Radioulnar Joint (DRUJ)

• Radius + Ulna

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Function

• Pronation and supination

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Ligaments of the Wrist

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1. Intrinsic Ligaments

• Between carpal bones

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Examples

• Scapholunate ligament
• Lunotriquetral ligament

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2. Extrinsic Ligaments

• Connect carpal bones to radius/ulna

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Examples

• Radioscaphocapitate ligament
• Radiolunate ligament
• Ulnolunate ligament

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Scapholunate Ligament

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Components

• Dorsal
• Volar
• Proximal fibrocartilage

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Most Important

• Dorsal component

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Function

• Provides wrist stability

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Clinical Importance

• Injury leads to:
  • Scapholunate dissociation
  • Carpal instability

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Lunotriquetral Ligament

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Components

• Dorsal
• Volar
• Proximal

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Function

• Stabilizes lunate–triquetrum joint

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Volar Extrinsic Ligaments

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Important Ligaments

• Radioscaphocapitate ligament
• Long radiolunate ligament
• Short radiolunate ligament
• Ulnolunate ligament
• Ulnotriquetral ligament

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Radioscaphocapitate Ligament

• Extends:
  • Radius — Scaphoid — Capitate
• Part of arcuate ligament complex

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Long Radiolunate Ligament

• Also called:
  • Radiolunotriquetral ligament

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Dorsal Wrist Ligaments

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Main Ligaments

• Dorsal intercarpal ligament
• Dorsal radiotriquetral ligament
• Dorsal distal radioulnar ligament

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Dorsal Intercarpal Ligament

• Extends:
  • Triquetrum — Scaphoid
  • Also attaches to trapezium & trapezoid

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First Carpometacarpal (CMC) Joint Ligaments

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Important for Thumb Stability

• Anterior oblique ligament
• Dorsal radial ligament
• Deep anterior oblique ligament

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Clinical Correlations

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1. Carpal Tunnel Syndrome

• Compression of:
  • Median nerve

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Symptoms

• Numbness
• Tingling
• Thenar weakness

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2. Intersection Syndrome

• Occurs at:
  • EPL crossing second compartment

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Symptoms

• Pain over dorsal wrist

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3. Scapholunate Ligament Injury

• Leads to:
  • Carpal instability

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Common Cause

• FOOSH (fall on outstretched hand)

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Summary

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Key Structures

• Six dorsal extensor compartments
• Nine flexor tendons in carpal tunnel
• Eight carpal bones
• Intrinsic and extrinsic ligaments
• Major nerves:
  • Median
  • Ulnar
  • Radial

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Clinical Importance

• Essential for diagnosing:
  • Tendon injuries
  • Ligament tears
  • Carpal instability