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2. MOB TCD
Superior and Inferior
Radioulnar Joint
Professor Emeritus Moira O’Brien
FRCPI, FFSEM, FFSEM (UK), FTCD
Trinity College
Dublin

3. MOB TCD
Supination
• Supination is when the bones of
forearm are parallel
• Palm of hand is facing anteriorly
• Supination with the elbow flexed is
a more powerful movement than
pronation

4. MOB TCD
Pronation
• Radius crosses the ulnar
• Palm of the hand is facing posteriorly
• Radial styloid is more distal than ulnar
styloid
• The axis of rotation passes through the
middle of the head of the radius to the
base of the styloid process of the ulna

5. MOB TCD
Supination and Pronation
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Three joints
Superior radioulnar joint
Interosseous membrane
Inferior radioulnar joint
Axis of rotation
Middle of head of radius
Base of styloid process of ulnar

6. MOB TCD
Superior Radioulnar Joint
•
•
•
•
•
•
•
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Synovial pivot joint
Circumference of head of radius
Radial notch of ulnar
Annular ligament covered with
articular cartilage
Quadrate membrane
Capsular ligament
Articular surfaces hyaline
cartilage
Synovial membrane continuous
with elbow joint

7. MOB TCD
Superior Radioulnar Joint
• Annular ligament attached to
anterior and posterior borders
of radial notch
• Lateral ligament of elbow to
upper margin
• Annular ligament covered with
articular cartilage

8. MOB TCD
Superior Radioulnar Joint
• Capsule is attached
• Lower border of the annular
ligament
• Neck of radius
• Ulnar below the radial notch

9. MOB TCD
Superior Radioulnar Joint
• Quadrate membrane
• Lower margin of the radial notch
ulnar
• Neck of radius
• Synovial membrane
• Lines capsule, non-articular
structures
• Continuous above the annular
ligament with synovial membrane
of elbow

10. MOB TCD
Interosseous Membrane
• Syndesmosis
• Fibres pass mainly
downwards and
medially
• Radius to ulna
• Extends origins of
muscles
• Pierced by anterior
interosseous artery
• Transmits force
from radius to ulna

11. MOB TCD
Interosseous Membrane

12. MOB TCD
Superior Radioulnar Joint
• Radial styloid is
more distal than
ulnar
• Synovial pivot joint
• L-shaped ulnar
notch of radius
• Lateral and distal
aspect of head of
ulna
• Triangular fibrocartilaginous disc

13. MOB TCD
Inferior Radioulnar Joint
• Radial styloid process is more
distal than ulnar styloid process

14. MOB TCD
Inferior Radioulnar Joint
• Synovial pivot
• L-shaped
• Medial and distal aspect of
head of ulna
• Ulnar notch of radius
• Triangular cartilaginous disc

15. MOB TCD
Inferior Radioulnar Joint
• Articular surfaces
• Hyaline cartilage
• Capsule just beyond articular
margins
• Synovial membrane lines
capsule and non-articular
structures
• Radial styloid process is more
distal than ulnar styloid process

16. MOB TCD
Supinators: Biceps Brachii and Supinator
• Biceps brachii with the elbow
flexed
• More powerful
• Musculocutaneous C5,6
• Supinator (two heads) with
elbow extended
• Posterior interosseous C5,6

17. MOB TCD
Supinator
• Supinator has two heads of origin
• The superficial head arises from
the lateral epicondyle of the
humerus, the lateral ligament of
the elbow and the annular
ligament
• The deep head arises from the
supinator crest and supinator
fossa of the ulna

18. MOB TCD
Supinator
• Supinator is inserted into the
upper third of the outer surface of
the radius
• When the elbow is extended
• The supinator muscle supinates
the forearm i.e. it rotates the
radius to turn the palm anteriorly
• Supplied by the posterior
interosseous nerve C6,7, which
passes between the two heads

19. MOB TCD
Pronator Teres
• Arises from two heads
• The common flexor origin
• The medial margin of the coranoid
process of the ulna

20. MOB TCD
Pronator Teres
• It is inserted into the most convex aspect
of the shaft of the radius
• The radial artery passes superficial to
the two heads
• The ulnar artery deep to the two heads
• The median nerve between the two
heads
• Its action is to assist pronator quadratus
in rapid or forceful pronation of the
forearm
• It is also a weak flexor of the elbow
• Median nerve C6

21. MOB TCD
Pronator Quadratus
• Arises from the anterior aspect of the
distal portion of the ulna
• Inserted into the distal aspect of the radius
• It is a pronator of the forearm
• Supplied by the anterior interosseous
branch of the median nerve
• The pronator quadratus is the prime mover
in pronation
• Pronator teres contracts when further
speed or strength is required

22. MOB TCD
Brachioradialis
• Arises from the upper third of the lateral
supracondylar line of the humerus
• Inserted into the distal aspect of the radius
• Radial nerve C5,6
• Flexor of elbow
• In the mid position it can initiate, either
pronation or supination
• It is used, for example, in the back cast
when fly-fishing

23. MOB TCD
Radial Epiphysis
• Slipped radial epiphysis

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