Lecture 16 - Elbow Flashcards
What are the bone structures of the elbow?
- Distal Humerus
- Proximal Ulna
- Proximal Radius
What are the articulations and supporting structures of the elbow?
- Humeroulnar articulation
- Humeroradial articulation
- Superior Radioulnar joint
What are the 2 movements of the elbow?
- Flexion-Extension
- Pronation-Supination
What is a valgus elbow?
lateral deviation of a distal segment with respect to proximal segment
What is a varus elbow?
medial deviation of a distal segment with respect to proximal segment
What is the arc of movement required for most ADLs in flexion-extension
30-130 degrees
What is the arc of movement for most ADLs of pronation and supination?
50 degrees for each
What are the characteristics of the humerus?
- Epicondyles
- Trochlea (medial)
- Capitulum (lateral)
- Coronoid fossa
- Olecranon fossa
How does the distal humerus flatten?
anteriorly and posteriorly
What is the degree of anterior curve of the distal humerus?
30 degrees
How many degrees of tilt does the distal humerus have?
6
What are the characteristics of the proximal ulna?
- Trochlear Notch
- Olecranon
- Coronoid Process
What are the characteristics of the proximal radius?
- Radial Head
- Radial Neck
- Radial tuberosity (biceps)
- Fovea (capitulum)
What are the 3 articulations within the elbow joint?
Humeroulnar
Humeroradial
Proximal radioulnar
What kind of joint is the humeroulnar joint?
hinge
What action is the humeroulnar joint responsible for?
flexion-extension
What is the joint space of the humeroulnar joint?
asymmetrical
What does the bone shape of the humeroulnar joint favor?
flexion excursion vs extension excursion
What is the humeroradial joint in greater contact with during flexion?
elbow
What is the primary action of the humeroradial joint?
flexion-extention
What kind of joint is the humeroradial joint?
hinge
What kind of joint is the superior radioulnar joint?
pivot
What is the primary function of the superior radioulnar joint?
pronation-supination
Where does the support of the superior radioulnar joint come from?
soft tissues only (no bone support)
What is the interosseous membrane?
an important static longitudinal stabilizer of the forearm (less contribution to forearm rotation)
What are the 3 primary static constraints of the elbow?
- Ulnohumeral articulation
- Anterior bundle of the medial collateral ligaments
- Lateral collateral ligaments
What are the 4 secondary constraints of the elbow?
- Radiocapitellar articulation
- Common origin of the flexors
- Common origin of the extensors
- Capsule
What bones stabilize the elbow?
- congruent articular surfaces
- radial head
- olecranon
- coronoid
Radial head stabilizes with stress in ___ direction
valgus
Olecranon stabilizes with stress in ___ direction
valgus
Coronoid stabilizes with stress in ___ direction
varus
What are the 3 bundles of the medial collateral ligaments?
anterior, posterior, transverse
What are the medial collateral ligaments important stabilizers with?
valgus stress
What are the 4 lateral collateral ligaments?
Lateral ulnar collateral
Accessory lateral collateral
Radial collateral
Annular
What are the lateral collateral ligaments important stabilizers with?
varus stress
How many DOF are in flexion/extension of the elbow? What axis?
1, medial-lateral axis
What angle does flexion/extension of the elbow carry?
5-10 degrees
What kind of angle is between the longitudinal axes of humerus and ulna?
valgus
What is pronation-supination?
rotation about a longitudinal axis passing through the radial head and the distal ulnar articular surface
What angle does pronation-supination occur?
120-140 degrees
What are the 4 types of muscles of the arm?
flexors, extensors, pronators, supinators
What are the 4 elbow flexors?
biceps brachii
brachialis
brachioradialis
pronator teres
When is the bicep less active?
when the arm is in full pronation
What are the 2 elbow extensors?
triceps brachii
anconeus
What are the pronators of the arm?
pronator teres
pronator quadratus
What are the supinators of the arm?
supinator
biceps
What does the elbow angle affect?
the amount of muscle force parallel and perpendicular to forearm
When a muscle crosses more than one joint, it will ___.
influence each joint
At shortest length, muscle at ___ length.
weakened
What is active insufficiency for multi-joint muscle?
at shortest length, muscle at weakened length
What 3 actions does the bicep do?
shoulder flexion, elbow flexion, supination
What is tennis elbow?
lateral epicondylitis
What is Golfer’s elbow?
medial epicondylitis
Lateral epicondylitis is the overuse of which muscle?
extensor carpi radialis brevis or extensor digitorum communis
What does an EMG show of lateral epicondylitis?
decreased extensor activity with two handed back hand
What muscle is overused during medial epicondylitis?
flexor-pronator musculature
What is there excess of during medial epicondylitis?
valgus force on elbow and medial tension
What do the articulating surfaces of the elbow do to motion?
guide and restict it
What do the collateral ligaments contribute to?
stabilize the elbow and limits extension
