2. Elbow Overview
● Hinge joint made up of
humerus, ulna and the
radius bones
● Function: properly place
hand in space by shortening
and lengthening the upper
limb
● Most upper extremity
movements involve the
elbow and radioulnar joints
3. Bones
● Ulna is much larger
proximally than radius
● Radius is much larger
distally than ulna
● Scapula and humerus
serve as proximal
attachments for muscles
that flex and extend the
elbow.
● Ulna and radius serve as
distal attachments for these
same muscles
4. Bones
● Scapula, humerus, and ulna
serve as proximal attachments
for muscles that pronate and
supinate the radioulnar joints.
● Distal attachments of the
radioulnar joint muscles are
located on radius
● Bony Landmarks
○ Lateral and medial
epicondyle
○ Olecranon process
○ Radial head
5. Joints
● 3 joints enveloped by common capsule
Joint From To Description
Humeroulnar
joint
trochlear
notch of
the ulna
trochlea of
humerus
- simple hinge joint
- allows movement of flexion & extension only
Humeroradial
joint
head of
the
radius
capitulum of
the humerus
- synovial ball and socket hinge type joint
- allows flexion, extension, pronation and
supination
Proximal
radioulnar
joint
head of
the
radius
radial notch
of the ulna
- tochoid (pivot) joint
- flexion or extension
- pronation and supination
6. Ligaments
● Ulnar collateral ligament
○ medial side of the elbow
○ extends from medial
epicondyle of humerus to
proximal portion of ulna
○ function is to prevent excessive
abduction of elbow joint
● Radial collateral ligament
○ lateral side of the elbow
○ extends from lateral epicondyle
of humerus to head of radius
○ function is to prevent excessive
adduction of elbow joint
7. Ligaments
● Ulnar collateral ligament
is critical in providing
medial support to
prevent the elbow from
abducting when stressed
in physical activity.
○ Many contact sports and
throwing activities place
stress on the medial aspect
of the joint, resulting in
injury.
8. Ligaments
● Radial collateral
ligament provides
lateral stability and is
rarely injured
● Annular ligament
provides stability for
radial head during
pronation and
supination
○ commonly injured in children
when arm pulled forcefully
9. Interosseous Membrane
The joint between
shafts of radius &
ulna held tightly
together between
proximal and distal
articulations by an
interosseous
membrane
10. Kinesiology of the elbow
● The elbow moves from
0 degrees of extension
to 145-150 degrees of
flexion.
11. Elbow motions
● Primarily involve movement
between articular surfaces of
humerus and ulna
● The humeral trochlea fits into
the ulna trochlea notch
● Radial head has a relatively
small amount of contact with
humerus
● As the elbow reaches full
extension, the olecranon
process fits into the olecranon
fossa
○ allows increased joint
stability when fully extended
12. Elbow motions
● As the elbow flexes 20
degrees or more, its
bony stability is
unlocked, allowing for
more side to side laxity.
● Stability in flexion is
more dependent on the
lateral (radial collateral
ligament) and the
medial (ulnar collateral
ligament).
13.
14. Movements
● Flexion
○ movement of
forearm to
shoulder by
bending the elbow
to decrease its
angle
● Extension
○ movement of
forearm away from
shoulder by
straightening the
elbow to increase
its angle
15. Movements
● Pronation
○ internal rotary
movement of radius
on ulna that results
in hand moving from
palm-up to palm-
down position
● Supination
○ external rotary
movement of radius
on ulna that results
in hand moving from
16. Pronation/Supination
● Radioulnar joint
○ trochoid or pivot joint
○ radial head rotates
around proximal ulna
○ distal radius rotates
around distal ulna
○ annular ligament
maintains radial head
in its joint
○ Supinate: 80-90
degrees from neutral
○ Pronate 70-90
17. Nerves
● All elbow and radioulnar joints muscles are
innervated from median, musculocutaneous,
and radial nerves of brachial plexus
19. Median Nerve
● Median nerve -
originates from
C6 & C7
○ Pronator teres
○ Pronator
quadratus
(anterior
interosseus nerve)
○ Sensation to palmar
aspect of hand & first
three phalanges, palmar
aspect of radial side of
fourth finger, dorsal
aspect of index & long
