Elbow Joint Flashcards
Function of the elbow is to serve the hand to
increase functional ROM of the upper extremity
stability
stable joint when performing forceful activities
mobility
- bring hand close to body (functional activities i.e. eating)
- reach object at a distance
biomechanically how does the elbow affect the function of the hand?
it helps maintain length-tension relationship
bones of elbow
humerus, radius, ulna
joints of elbow
humeroulnar
humeroradial
radioulnar (superior/inferior)
humeroulnar
hinge – 1 deg of freedom
humeroradial
hinge – 1 deg of freedom
radioulnar – superior/inferior
pivot – 1 deg of freedom
elbow flexion/extension
humeroulnar & humeroradial
elbow pronation/supination
radioulnar superior & inferior
bony stability of humeroulnar
- ulna:
trochlea fossa
bony stability of humeroulnar
- humerus:
trochlea
humeroulnar stability
- coronoid process
increases resistance to posterior dislocation with flexion
humeroradial stability:
- resistance vs. _________ & prevents __________ beyond 90 degrees
valgus stresses;
posterior dislocation
valgus stresser (elbow)
distal part of the arm deviates laterally
lateral- more compression
medial - more tensile forces
medial collateral ligament (triangular) – ANTERIOR FIBERS
primary stabilizer vs valgus stress (20 -120)
STRONGEST PORTION IN TERMS OF medial stability
medial collateral ligament (triangular) – OBLIQUE FIBERS
vs. valgus stress & assists in approximation
medial collateral ligament (triangular) – POSTERIOR FIBERS
vs. valgus stress
lateral collateral ligament
- fan
- weaker
- attaches to annular ligament
- stabilizer vs. varus stress = poor tensile properties
anconeus assists in
stability vs. varus forces
varus stressors (elbow)
deviate medially
joint capsule encompasses:
humeroulna
humeroradial
proximal radioulna
carrying angle
long axis of humerus and long axis ulna (anatomical position)
- — summary- line of the humerus compared to the angle of the radio ulna
- trochlea extends further distally than the capitulum
normal deg of carrying angle
10 deg to 15 deg of valgus
– greater in females
trochlea extends ______ than the capitulum
carrying angle
further distally
the greater the carrying angle the greater the ______ stress on elbow, the greater the ______ forces medially, the greater the ______ forces laterally
valgus;
tensile;
compressive
ROM flexion/extension of elbow
0 - 140 deg
functional ROM
30 - 130
elbow is predominantly a ________ motion (arthrokinematics)
gliding motion
final 5-10 deg of flexion extension is ________ (arthrokinematics)
rolling
___ (#) of muscles cross the elbow, can affect the movement of the ____ & ____
15;
wrist;
shoulder;
muscle function depends on
- location of muscles
- elbow position and adjacent joints (active & passive insufficiency)
- position of forearm
- magnitude of applied load
- type of contraction
- speed of motion
annular ligament prevents
dislocation of radial head
annular ligament is lined with
articular cartilage
annular ligament blends with
capusle
annular ligament’s lateral aspect blends & is reinforced by
lateral collateral ligament
Quadrate ligament
inferior edge of radial notch of ulna to the neck of radius
quadrate ligament reinforces
the inferior aspect of the capsule
quadrate ligament helps
the radial head maintain position
&
limits the rotation of the radial head
superior radioulnar ligaments
annular
quadrate
superior radioulnar joint
- radial notch of the ulna
- annular ligament
- capitulum of humerus
- radial head
inferior radioulnar joint
- ulnar notch of the radius
- articular disk
- head of the ulna
inferior radioulnar ligaments
- anterior & posterior radioulnar ligament
- interosseous membrane
anterior & posterior radioulnar ligament
ulna head –> ulnar notch of radius
interosseous membrane
- binds radius & ulna together
- transmits forces
- taut in neutral
- relaxed in supination/pronation
radioulnar motion
pronation & supination
AOR of the radioulnar joint
capitulum –> radial head –> upper 1/2 of radial shaft –> ulna styloid process
radioulnar joint ROM pronation
70 degees
OR
80 degrees
radioulnar joint ROM supination
85 degrees
OR
80 degrees
in general, pronation and supination has _____ ROM
80 - 90 degrees
functional ROM - pronation
50 deg
functional ROM - supination
55 deg
wrist finger flexor muscles from _________ of the humerus
except for _________
medial epicondyle
FDP – originates from the proximal 3/4 of the anterior & medial shaft of the ulna
wrist finger extensor muscles from the ________ of the humerus
lateral epicondyle
wrist/finger flexor/extensor muscles reinforce the
elbow joint capsule providing stability to the elbow complex
flexors of the elbow
brachialis
biceps brachii
brachioradialis
extensors of the elbow
triceps
anconeus
pronators of the elbow
pronator teres
pronator quadratus
brachioradialis (weakly)
supinators of the elbow
biceps brachii
supinator
brachioradialis (weakly)
nursemaids elbow
- annular ligament slides over the radial head & impinges
- generally occurs from an extended/pronated pull
- generally 1 - 3 years old (usually no older than 5)
- can occur up to preteen
nursemaid elbow is more likely to occur in _____ than ____
girls than boys
nursemaid elbow is more likely to occur on the _____ side than the ______ side
left side than on the right side
nursemaid elbow is most likely to redislocate _______ post injury
3-4 weeks
tennis elbow
lateral epicondylitis
- occurs at origin of extensor carpi radialis brevis
- —–> origin is thin therefore more prone to stressor forces
golfer’s elbow
medial epicondylitis
- occurs at flexor carpi radialis and pronator teres
- less common
- also overhead throwing injury –> valgus forces at elbow
cubital tunnel
compression of the ulnar nerve at the elbow
- between the medial epicondyle and the olecranon
- flexor carpi ulnaris stress
