PHTY101 Lecture Notes - Lecture 5: Proximal Radioulnar Articulation, Joint Capsule, Synovial Membrane
PHTY 101 – WEEK 5
3.4 Identify, classify and describe the elbow joint
• Classification: synovial, uniaxial, hinge
• Movements:
- Flexion and extension- transverse axis
- Flexion limited by soft tissue
- Extension limited by bones
• Close packed position: midway between pronation and
supination, with 90 degrees of flexion
• Responsible for orientation of hand in relation to trunk
• Articular surfaces:
• 2 different articulations combine to make one
functional unit
- Distal humerus:
- Capitulum- head
- Trochlear pulley shaped
- Radius and ulna:
- Head of radius- articulates with capitulum of humerus, dip/ concavity
for capitulum to sit
- Trochlear notch of ulna- articulates with trochlear head of humerus,
has dips for humerus
3.5 Identify, classify and describe the superior radioulnar joint:
• Classification: synovial, uniaxial, pivot
• Movements:
- Pronation and supination- longitudinal axis
• Stability comes from connective tissue (not from bony factors)
• Articular surfaces:
- Head of radius
- Radial notch of ulna
• Articular capsule: common capsule for elbow and superior radioulnar
- Attaches at articular margins of humerus- doesn’t attach to head of
radius
- Thickest and strongest at sides of joints, relatively weak anteriorly
and posteriorly- strengthened by collateral ligaments on sides
• Synovial membrane: also common to both joints
• Extra synovial fat pads:
- Occupy the fossae when the bony projections do not
- Proprioceptive
• Ligaments:
- Annular:
- Shaped like a ring
- Prevents inferior dislocation of head of radius
- Both of its attachments on ulna
- Wraps around head and neck of radius and holds it in notch
- Flexible to allow radius to pivot through pronation and supination
- Wider superiorly than inferiorly
- Collateral ligaments:
- Tense throughout flexion and extension range
- Radial collateral- prevents adduction
- Ulnar collateral- prevents abduction
3.6 Identify, classify and describe the inferior radioulnar joint
• Classification: synovial, uniaxial, pivot
• Movements:
- Pronation and supination- longitudinal axis
• Articular surfaces:
- Ulnar notch of radius
- Head of ulna
• Stability gained from surrounding soft tissue
• Ulna smaller at distal end, radius smaller at proximal end
• Interosseus membrane binds bones together
• Articular disc:
- From styloid of ulna to margin of ulnar notch of radius
- Therefore not between the articular surfaces
- More like a ligament
- Unlike other joints, disc sits underneath joint
3.7 Identify, classify and describe the intermediate radioulnar joint
• Classification: Non synovial, fibrous, syndesmosis
- Fibres run downward from radius to ulna
- Fibres in diagonal direction- role in dissipating forces between bones
- Tight in supination, loose in pronation
- Site for muscle attachment
- Binds bones together
- Hole at top of membrane- allows things to pass through e.g. blood
vessels
• Dissipating forces:
- Radius cops force initially
- Transferred to ulna, then humerus, shoulder girdle and axial skeleton
