MRI Elbow Joint Anatomy ligaments, tendon Common Elbow Pathologies on MRI

MRI Elbow Joint Anatomy

1. Bones

The elbow joint is formed by three bones:

• Humerus (upper arm)

• Ulna (forearm — medial side)

• Radius (forearm — lateral side)

Articulations:

• Humeroulnar joint: hinge movement (flexion/extension)

• Humeroradial joint: rotational movement

• Proximal radioulnar joint: supination/pronation

2. Ligaments

These provide stability to the elbow joint.

• Ulnar Collateral Ligament (UCL) / Medial Collateral Ligament (MCL)
  ➤ Prevents valgus stress (seen in throwing injuries)

• Radial Collateral Ligament (RCL) / Lateral Collateral Ligament (LCL)
  ➤ Prevents varus stress

• Annular Ligament
  ➤ Wraps around the radial head and holds it in place during rotation

3. Tendons

Tendons connect muscle to bone.

• Common Extensor Tendon (lateral epicondyle)
  ➤ Muscles for wrist extension (affected in Tennis Elbow)

• Common Flexor Tendon (medial epicondyle)
  ➤ Muscles for wrist flexion (affected in Golfer's Elbow)

• Distal Biceps Tendon (inserts on radial tuberosity)
  ➤ Elbow flexion and supination

• Triceps Tendon (inserts on olecranon)
  ➤ Elbow extension

4. Function

• Flexion/Extension (hinge action)

• Supination/Pronation (rotational movement)

• Stability for lifting, pushing, and rotation of the forearm

• Coordination between shoulder and wrist movements

MRI Appearance of Elbow Anatomy

Sequences:

• T1W: anatomy and bone marrow

• T2/STIR: fluid, edema, pathology

• PD FS: tendons, ligaments, cartilage

Common Elbow Pathologies on MRI

🔹1. Lateral Epicondylitis (Tennis Elbow)

• Degeneration or partial tear of the common extensor tendon

• T2 hyperintensity, tendon thickening, peritendinous edema

🔹 2. Medial Epicondylitis (Golfer’s Elbow)

• Involves common flexor tendon

• Similar MRI findings as above, but on the medial side

🔹 3. UCL Tear (Thrower’s Elbow)

• Common in athletes (baseball pitchers)

• Partial/complete tear; seen as discontinuity or high T2 signal in UCL

🔹 4. Biceps Tendon Tear (Distal)

• High T2 signal and gap at radial insertion

• May show tendon retraction

🔹 5. Triceps Tendon Tear

• Rare; seen in bodybuilders or trauma

• Disruption at olecranon insertion

🔹 6. Elbow Effusion

• Fluid in the joint capsule

• Non-specific, may indicate trauma, infection, or arthritis

🔹 7. Osteochondritis Dissecans (Capitellum)

• Common in adolescents

• Cartilage and subchondral bone injury seen on sagittal/axial T2

🔹 8. Ligament Injuries

• LCL or annular ligament sprains/tears

• May show increased signal, irregular contour, or avulsion

🔹 9. Nerve Compression (e.g., Cubital Tunnel Syndrome)

• Ulnar nerve compression at the elbow

• T2 hyperintensity, swelling of nerve

🔹 10. Fractures & Bone Contusions

• Seen as marrow edema on T2W/STIR

• Cortical disruption for fracture

 Summary Table

Structure	Function	MRI Pathology
UCL	Valgus stress resistance	Partial/complete tear
RCL	Varus stress resistance	Injury or laxity
Common Extensor Tendon	Wrist extension	Lateral epicondylitis
Common Flexor Tendon	Wrist flexion	Medial epicondylitis
Biceps/Triceps Tendons	Flexion/extension	Tendon rupture
Bones (humerus, ulna, radius)	Structure, motion	Fractures, OCD
Annular Ligament	Radial head stability	Subluxation, tear