joints of upper extremity

1. Radio-ulnar joints
Dr.K.Iyer
Professor-Anatomy

2. Classification
• Synovial
• Uniaxial
• Pivot joint.
• There are 2 joints
between radius &
ulna.
• Superior &
• Middle

3. Superior R U
joint
• Articulating
surfaces—
• Medial surface
of head of
radius &
• Radial notch of
ulna.
• Head of radius
is held by
annular
ligament .

4. Annular ligament
• Annular ligament—
• It is attached to the
margins of radial
notch of ulna.
• It is NOT attached to
radius.
• Its lower margin is
narrower than the
upper. So it holds the
neck of radius.
• Superiorly,It is
attached to lower
border of elbow joint
capsule & lateral
collateral ligament.

5. Capsule
• Proximal border of
annular ligament
blends with elbow joint
capsule.
• Posteriorly , it
broadens, divides into
2-3 bands & are
attached to posterior
margin of radial notch.
• Inferiorly, it loosely
holds the neck of
radius.

6. Accessory
ligaments
• Quadrate ligament—
• Extends from lower margin
of ulnar notch to neck of
radius.
• It closes the joint inferiorly.

7. Oblique cord
• Extends from ulnar to
radial tuberosities.
• Fibers are at right
angles to
interosseous
membrane fibers.
• Its functions are
unknown.

8. Synovial membrane
• Annular ligament is lined
by synovial membrane of
elbow joint.
• It protrudes deep to
annular ligament &
reaches the neck of
radius.
• A crescentic fold of the
same also protrudes
posteriorly between
radius & ulna.
• The fibrous layer of the joint
capsule encloses the joint
and is continuous with that of
the elbow joint.
• The synovial membrane lines
the deep surface of the
fibrous layer and non-
articulating aspects of the
bones. The synovial
membrane is an inferior
prolongation of the synovial
membrane of the elbow joint.

9. Relations
• The external surface of the
annular ligament blends with
the radial collateral ligament .
• It provides an attachment for
part of supinator.
• Posterior --anconeus and the
interosseous recurrent artery.
• Internally the ligament is
thinly covered by cartilage
where it is in contact with the
radial head.

10. Inferior R U Joint
• Synovial
• Uniaxial
• Pivot type
• Articulating
surfaces—
• Lateral surface of
head of ulna & ulnar
notch of lower end of
radius.

11. Inferior radioulnar joint

12. Articular disc-inf. R U joint
• Is triangular in shape.
• Is fibrocartilaginous.
• Is on the lower surface of
head of ulna to radial
notch.
• This is a very strong
band holding the bones
together.
• Its apex is attached to
lateral depression of ulnar
styloid process.
• Base is attached to radial
notch & margins to carpal
ligament.

13. Articular disc

14. Inferior radio ulnar joint
• Capsule: The capsule encloses the joint (articular
surfaces) but is lax superiorly. It is thicker anteriorly &
posteriorly.
• Ligaments: Weak anterior and posterior ligaments
• strengthen the capsule.
• Articular disc: This is triangular and composed of
fibrocartilage.
• It shuts off the distal radioulnar joint from the wrist
and strongly unites the radius to the ulna.

15. Inferior radio
ulnar joint
• The synovial membrane extends
superiorly between the radius and
the ulna to form a recess of the
distal radioulnar joint .
• This redundancy of the synovial
capsule accommodates the
twisting of the capsule that occurs
when the distal end of the radius
travels around the relatively fixed
distal end of the ulna during
pronation of the forearm.
• Ligaments of the Distal
Radioulnar Joint
• Anterior and posterior ligaments
strengthen the fibrous layer of the
joint capsule of the distal
radioulnar joint.
• These relatively weak transverse
bands extend from the radius to
the ulna across the anterior and
posterior surfaces of the joint.

16. Inferior radio-ulnar joint
• A fibrocartilaginous articular disc
called triangular ligament.
• It binds the ends of the ulna
and radius together and is the
main uniting structure of the
joint .
• The proximal surface of this
triangular disc articulates with the
distal aspect of the head of the
ulna. Hence, the joint cavity is L-
shaped in a coronal section; the
vertical bar of the L is between
the radius and the ulna, and the
horizontal bar is between the
ulna and the articular disc .
The articular disc separates the
cavity of the distal radioulnar
joint from the cavity of the wrist
joint.

17. Relations

18. Nerve supply
• Superior radio-ulnar joint– median, ulnar
musculo cutaneous, radial nerves.
• Inferior radio-ulnar joint—anterior &
posterior inter-osseous nerves.
• Blood supply—superior joint gets
branches from anastomosis around elbow
joint.(radial & ulnar collateral arteries)

19. Movements
• Definition-
• Since it is an uniaxial joint, only
rotation occurs.
• Is called pronation-
supination.
• Pronation- hand rotating
• medially in such a manner
that the palm comes to face
posteriorly.
• supination is a reversal of
this process so that the hand
returns to the anatomic
position and the palm faces
anteriorly.
• The axis—
• passes through the head
of the radius above and the
attachment of the apex of
the triangular articular disc
below.

20. Pronation-supination
• Pronation and supination of the
hand occur entirely in the
forearm It involve rotation of the
radius and movement of the
distal end of the radius over the
ulna .
• The superior articular surface of
the radial head spins on the
capitulum .
• At the same time, the articular
surface on the side of the head
slides against the radial notch of
the ulna and areas of the joint
capsule and annular ligament of
radius.
• At the distal radio-ulnar joint, the
ulnar notch of the radius slides
anteriorly over the convex
surface of the head of the ulna

21. Axis
• Axis of pronation &
supination is not fixed.
• The axis normally stated is
when forearm is resting on a
surface & ulna is
stationary & the forearm is
supinated.
• ‘In- space’ pronation is
more important & is
required for all
movements of ‘working’
hand . This happens when
ulnar movement is
marked.
• .
• In ‘In- space’ pronation,
conventional axis keeps
shifting laterally till it
passes between radius &
ulna at both radioulnar
joints. When prolonged
through the digits, it
passes through ring &
middle finger

22. Pronation-supination
• Supination is a more
powerful & anti- gravity
movement.
• Used in tightening nuts,
bolts & screws, closing
taps, picking up objects
for inspection &
manipulation.
• After completion of
movement, bones of
forearm lie side by side,
parallel to each other.
• Pronation is a primary positional
movement.
• Is aided by gravity.
• At the end of the movement, radius
lies on medial side of ulna with its
dorsal surface on anterior aspect of
forearm.
• Radius lies across the front of ulna.
• Head of radius spins on capitulum, &
rotates in ulnar notch.
• Radial lower end swing around head
of ulna.
• Head of Ulna itself moves
posterolaterally in pronation &
anteromedially in supination.

23. Pronation-supination
• It is a rotatory
movement.
• Axis passes through the
centre of the radial head
to lateral surface of
ulnar styloid process. it
is 140-150 degrees
• With the elbow
extended, it is 360
degrees due to humeral
rotation & scapular
movements.

24. Distal Radioulnar Joint
Movements
• During pronation—
• the distal end of the
radius moves (rotates)
anteriorly and
medially, crossing
over the ulna
anteriorly & comes to
lie on medial side of
ulna with its dorsal
surface facing
anteriorly.
• During supination—
• the radius uncrosses
from the ulna, its
distal end moving
(rotating) laterally and
posteriorly so the
bones become
parallel.

25. Inferior radio
ulnar joint
• The inferior end
of the radius
moves around
the relatively
fixed end of
the ulna during
supination and
pronation of the
hand.

26. Movements
• During rotation, the
radius moves around
the ulnar head.
• Ulna moves laterally
(abduction)

27. Ulnar movement
• In pronation, the head of the radius rotates within the
annular ligament,
• The distal end of the radius with the hand moves bodily
forward.
• The ulnar notch of the radius moving around the
circumference of the head of the ulna
• In addition, the distal end of the ulna moves laterally
so that the hand remains in line with the upper limb
and is not displaced medially
• This movement of the ulna is important when using an
instrument such as a screwdriver because it prevents side-
to-side movement of the hand during the repetitive
movements of hand.

28. Muscles-
Proximal & distal
Radioulnar Joint
Supination is by the supinator
and biceps brachii (stronger in
fast movements in flexion &
in flexed elbow position .)
Assisted by extensor carpi
radialis longus
Pronation is by the
pronator quadratus (primarily)
and
pronator teres (secondarily), &
against resistence.
Assisted by The flexor carpi
radialis, palmaris longus, and
brachioradialis ( when the
forearm is in the midpronated
position).

29. Accessory movements
• These include
anterior and posterior
translation of the
radial head on the
ulnar radial notch,
and
• of the ulnar head
likewise on the radial
ulnar notch.
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30. Interosseous
membrane
• Inter-osseous borders of
radius & ulna face each other
& give attachment to inter-
osseous membrane.
• Fibers pass obliquely
downwards from radius to
ulna.
• They transmit forces from
wrist joint to radius to ulna &
then to elbow joint.
• It holds the 2 bones
together yet separate. It
restricts the movements to a
certain extent.
• Gives attachment to muscles.
• Is taut in midprone position

31. Integrity of the joints
• The integrity and functions of the humeroradial joint
proximal radioulnar joint complex ,depends primarily on
the combined radial collateral and anular ligaments.
• The combined synovial proximal and distal radioulnar
joints plus the interosseous membrane enable
pronation and supination of the forearm.
• The anular ligament of the proximal joint, articular disc of
the distal joint, and interosseous membrane not only
hold the two bones together while permitting the
necessary motion between them, but they (especially the
membrane) also transmit forces received from the hand
by the radius to the ulna for subsequent transmission to
the humerus and pectoral girdle.

32. Working position of hand
• In mid prone position the wrist joint can be
abducted & adducted to manipulate
instruments.
• Supination is used in tightening screws.

33. Dislocation of radius

34. Dislocation of Radial Head
• Preschool children, particularly girls, are vulnerable to incomplete
temporary dislocation of the head of the radius (also called nursemaid's
elbow and pulled elbow). The history of these cases is typical.
• The child is suddenly lifted (jerked) by the upper limb while the forearm is
pronated (e.g., lifting a child into a bus) The child may cry out, refuse to
use the limb, protects the limb by holding it with the elbow flexed and the
forearm pronated.
• The sudden pulling of the upper limb tears the distal attachment of the
annular ligament, where it is loosely attached to the neck of the radius.
The radial head then moves distally, partially out of the anular ligament.
• The proximal part of the torn ligament may become trapped between the
head of the radius and the capitulum of the humerus. The source of pain
is the pinched anular ligament.
• Treatment of the subluxation consists of supination of the child's forearm
while the elbow is flexed .
• The tear in the anular ligament soon heals when the limb is placed
in a sling for 2 weeks.

35. Radioulnar Joint Disease
1. Infection of the elbow joint invariably involves the
proximal radioulnar joint as these two joint communicate
with each other.
2. The strength of the proximal radioulnar joint depends on
the integrity of the strong annular ligament.
3. Rupture of this ligament occurs in cases of anterior
dislocation of the head of the radius on the
capitulum of the humerus.
4. In young children, in whom the head of the radius is still
small and undeveloped, a sudden jerk on the arm can
pull the radial head down through the annular ligament.

36. Thank You !