lecture 8- elbow and wrist function Flashcards
function of the elbow
adjust the over-all function length of the upper limb
two interlocking joints
ulnohumeral and radiohumeral
the stability of the joint is dependent on the ___________- when the elbow is flexed
collateral ligaments
ulnohumeral & radiohumeral ligaments
articular capsule- encloses all three articulations of the elbow region
medial collateral ligament- provides resistance to valgus forces
lateral collateral ligament- provides resistance to various forces
valgus
forces that push toward the body
varus
forces that push away from the centre of the body
normal caring angle
5-10 degrees
excessive cubitus valgus
30 degrees
cubits varus
-5 degrees
gun suck deformity
-15 degrees
proximal radioulnar joint
supination and pronation give the upper extremity a mechanical advantage and improve function consider turning a screwdriver
interosseous membrane
holds the radius and ulna together. useful in absorbing and transmitting forces received by the hand- especially when weight bearing on the upper extremity
muscles acting on the elbow
most muscles that act on and cross the shoulder joint with the exception of supinators and pronators. stability at the shoulder joint has an impact on the function of the elbow joint
muscles with an organ at the elbow
common extensor= lateral epicondyle
common flexors= medial epicondyle
elbow felxors function
elbow flexor torques produced with the forearm are 20-25% greater than when they are pronated
elbow flexor function
combining elbow flexion with shoulder extension naturally increases the torque of biceps. minimizes the rate and amount of shortening required by the long head of the biceps to completely flex the elbow
combining shoulder flexion with elbow extension
minimizes the rate and amount of shortening required by the long head of the triceps
supinators/ pronators- function
as a group supinators produce 25% greater isometric torque than pronators
the stability of the elbow can be altered by:
weak imbalances
-weak muscles
-tight structures
instability
-ligament laxity
-injury
loss of neural control
-impacting dynamic stability
ligaments of the elbow
radiohumeral& ulnohumeral ligaments
radioulnar ligaments
radiohumeral& ulnohumeral ligaments action
action
articular capsule
medial collateral ligament
lateral collateral ligament
radioulnar
annular ligament
interosseous membrane
limiting structures
movement
ligaments
muscles
movement- flexion, joint capsule posteriorly soft tissue approximation, triceps brachii
extension, joint capsule anteriorly/ collateral ligaments, brachialis, biceps brachii, brachioradialis
supination- interosseous membrane- pronator teres \ pronator quadratus
pronation- interosseous membrane, supinator, biceps brachii
active restraints- muscles
Biceps Brachii
Supinates forearm and flexes the elbow.Short head resists dislocation of the shoulder
Brachialis
Flexes the elbow in all positions.
Brachioradialis
Flexes elbow joint, especially in semi-
pronated position.
Triceps Brachii
Primary extensor of the elbow joint.
Anconeus
Assists triceps in extending the elbow,
stabilizes the elbow joint, may abduct the
ulna during pronation.
Supinator
Supinates forearm
Pronator Teres
Pronates forearm
Pronator Quadratus
Pronates forearm
elbow conditions
lateral epicondylitis
elbow instability
dramatic dislocation
excessive strain
lateral epicondylitis
tendinopathy
tendons become inflamed (micro tearing or degeneration) usually due to overuse
elbow instability
dislocation-
elbow dislocations or subluxations are usually the result of a fall on the outstretched hand (FOOSH)
excessive strain-
Tommy John surgery
reconstruction of the UCL. usually replaced with tendon of the palmaris longus. common amongst pitchers in baseball
