2. The radioulnar joints
• The radioulnar joints are two locations in
which the radius and ulna articulate in the
forearm:
• Proximal radioulnar joint
• Distal radioulnar joint
• Both of these joints are classified as pivot
joints, responsible for
– Pronation and
– Supination of the forearm.
3. Proximal radioulnar joint
•This is located near the elbow
• This is an articulation
between the head of the
radius, and the radial notch of
the ulna.
4. Distal radioulnar joint
•This is located near the wrist,
• This is an articulation
between the ulnar notch of
the radius, and the ulnar head.
7. Proximal Radioulnar Joint(PRUJ)
• Type: Uniaxial Synovial pivot joint
• Capsule: The capsule encloses the joint and is
continuous with that of the elbow joint.
• Synovial membrane: This is continuous above with
that of the elbow joint. Below it is attached to the
inferior margin of the articular surface of the radius
and the lower margin of the radial notch of the
ulna.
• Nerve supply: Branches of the median, ulnar,
musculocutaneous, and radial nerves
8. Important Relations of (PRUJ)
• Anteriorly:
–Supinator muscle and the radial
nerve
• Posteriorly:
–Supinator muscle and the
common extensor tendon
9.
10. Proximal/superior Radioulnar Joint
• The proximal radioulnar joint is enclosed with in the
same articular capsule of the elbow.
– The radial head is held in place by the annular radial
ligament, which for s a collar arou d the joi t.
– The annular radial ligament is lined with a synovial
membrane.
• Movement is produced by the head of the radius
rotating within the annular ligament.
• Two movements possible at this joint
– Pronation.
– Supination.
11.
12. Oblique cord
• A narrow ligamentous structure
which extends from radius below the
tuberosity to the apex of coronoid
process of ulna.
• Function: unknown
• It represents degenerate part of
flexor pollicis longus origin.
19. Distal Radioulnar Joint
• This distal radioulnar joint is located just proximally
to the wrist joint. It is an articulation between the
ulnar notch of the radius, and the ulnar head.
• A fibrocartilaginous ligament articular diskof the
wrist joint separates the distal radioulnar joint from
the wrist joint.
• Like the proximal radioulnar joint, this is
a pivot joint, allowing for:
– Pronation
– Supination
20.
21. Distal Radioulnar Joint
• Type: Uniaxial Synovial pivot joint
• Capsule: The capsule encloses the joint but is
deficient superiorly.
• Ligaments: Weak anterior and posterior ligaments
strengthen the capsule.
• Articular disc:
• Synovial membrane: This lines the capsule passing
from the edge of one articular surface to that of the
other.
• Nerve supply: Anterior interosseous nerve and the
deep branch of the radial nerve
22. Articular disc
• A triangular, fibrocartilaginous
articular disc is attached by its base
to the lower margin of the ulnar
notch of the radius and by its apex to
a fossa at the base of the ulnar
styloid.
• The proximal surface of the disc
articulates with the ulnar head.
23.
24. Important Relations of DRUJ
• Anteriorly:
–The tendons of flexor
digitorum profundus
• Posteriorly:
–The tendon of extensor digiti
minimi
25.
26.
27.
28.
29.
30. Interosseous Membrane
• The interosseous membrane is a sheet of connective
tissue that joins the radius and ulna together between
the radioulnar joints.
• It spans the distance between the medial radial border,
and the lateral ulnar border. There are small holes in
the sheet for the forearm vasculature.
• This connective tissue sheet has three major functions:
1. Holds the radius and ulna together during pronation
and supination of the forearm, providing addition
stability.
2. Acts as a site of attachment for muscles in the
anterior and posterior compartments of the forearm.
3. Transfers forces from the radius to the ulna.
31.
32.
33.
34.
35.
36.
37. Clinical Relevance
• Fractures to the Radius and Ulna
• Although the radius and ulnar are two distinct and
separate bones, when dealing with injuries to the
forearm, they can be thought of as a ring.
– A ring, when broken, usually breaks in two places. The
best way of illustrating with is with a polo mint – it is
very difficult to break one side without breaking the
other.
• This means that a fracture to the radius or the ulna
usually causes a fracture or dislocation of the other
bone.
38. Fractures
• There are two classical fractures:
• Monteggia’s Fracture – Usually caused by a force
from behind the ulna. The proximal shaft of ulna
is fractured, and the head of the radius dislocates
anteriorly at the elbow.
• Galeazzi’s Fracture – A fracture to the distal
radius, with the ulna head dislocating at the distal
radio-ulnar joint.
