L6.2 Elbow joint

Question 1

Elbow joint

Ligaments, blood, nerve supply

Answer 1

• Compound hinge joint (more than 2 articular surfaces)
• Capsule houses 2 joints (elbow & proximal radioulnar)
• No articular discs, but hyaline cartilage present → smoothen movements
• Ligaments:
  
  • Ulnar collateral ligament - 3 bands (from medial epicondyle)
    
    • ANT: → coranoid process
    • POS: → Olecranon process
    • Oblique: Connects the 2 processes
  • Ulna lig stops excessive valgus (away from midline) deviation
  • Radial Collateral lig (from lat epicondyle)
    
    • Blends with annular lig (~ head of humerus) not attached to bone
• Blood supply:
  
  • Branches of brachial A
• Nerve supply:
  
  • Musculocutaneous, radial, ulnar

Question 2

What is the function of the articular capsule, fat pads, and bursae?

Answer 2

• Articular capsule = lax (due to singular movement of elbow)
• Fat pads (within fossa)
  
  • Olecranon, radial, coranoid
• Olecranon bursae → prevents excessive friction

Question 3

What is the carrying angle?

Answer 3

• Trochlear is at and oblique angle → during exnteion, causes valgus deviation = carrying angle
  
  • Females > males
  • Adults > children

Question 4

Function of the interosseous membrane?

Answer 4

• Interosseous membrane transmits force 20% proximally, 80% distally
  
  • Fracture at one end may lead to dislocation at the other

Question 5

PROX R-U joint

Ligament, blood, nerve supply

Answer 5

• Head radius + radial notch of ulna
• Laxity in articular capsule → creates sacciform recess
• Blood supply:
  
  • branches of deep radial & radial A
• Nerve supply:
  
  • Median, musculocutaneous, radial
• Lig:
  
  • Annular lig (main stabiliser)
    
    • Attaches to ulna
  • Quadrate lig (INF of annular lig)
    
    • Keeps radius on ulna
  • Interosseous membrane

Question 6

DISTAL R-U joint

Answer 6

• Head ulna + ulnar notch on radius
• Lig:
  
  • ANT & POS lig of distal R-U joints
• Blood supply:
  
  • ANT & POS interosseous A
• Nerve supply:
  
  • Median, radial intersseous N

Question 7

What is the position of maximum stability?

Answer 7

Mid pronation (also the only time when brachioradialis helps pronation)

Question 8

Injuries of the proximal humeral ulnar joint?

Answer 8

• joint fracture/dislocation
• Fall on flexed elbow →
  
  • break olecranon → affects ulna nerve
  • Breaks coranoid process → affects median nerve

Question 9

Injuries of the proximal humeral radial joint?

And how is the dislocation reduced/fixed?

Answer 9

• joint dislocation:
  
  • Annular lig lax
  • Displace head of radius
  • Muscles pull radial head superiorly
• Reduction of dislocation:
  
  • Supinate forearm
  • Push proximally
  • Joint in flexion

Question 10

What are some clinical considerations around the elbow joint?

Answer 10

• Bursitis
• Epicondylitis
• Avulsion fractures
  
  • Med epicondyle of humerus
  • Olecranon process (inhibit ulna)
  • Coranoid process (inhibit ulna)
  • Styloid process (inhibit ulna)
• Supracondylar fracture of humerus → Volkmann’s ischemia