4.1 Joints of the elbow Flashcards
What is the blood and nerve supply to the elbow joint?
Blood: branches of brachial artery (posteriorly = profunda brachii)
Nerve: musculocutaneous, radial, ulnar
What are the features of the elbow joint?
- compound joint between humerus, ulna and radius
- hinge joint
- capsule houses 2 distinct joints = elbow, proximal radioulnar
- no articular disc (meniscus, hyaline cartilage lining articular stuff)
*radioulnar joint only contacts humerus in complete flexion
What are the ligaments of the elbow?
Ulnar collateral ligament: 3 bands
- anterior = connects coronoid process of ulna & olecranon process of
- posterior = coronoid process & medial epicondyle
- oblique
Radial collateral ligament
*blends with annular ligament
Articular capsule lax anteriorly and posteriorly
Fat pads - olecranon, radial, coronoid
*aid in spread of synovial fluid as well cushioning joint
Olecranon bursa
What are the movements at the elbow joint?
Flexion
- mostly between humerus and ulna
- radial contact at close-packed position: 90deg flexion and midway b/w pronation/supination
Extension
- oblique angle of trchlear
- carrying angle: elbow extension, forearm supination, adults > children, females > males
- valgus vs varus arm
What are the flexion muscles at the elbow joint?
Biceps brachii
Brachialis
Brachioradialis
*with muscles that cross two joints, they have a stronger action at the distal joint, ie. biceps exert greater pull at distal end, especially when forearm is supinated
What are the extension muscles at elbow joint?
Triceps brachii
Anconeus: aids in extension of arm, stops excessive pinching of muscle when elbow joint is fully extended
Radioulnar joints
- at each end of radius
- b/w radial notch on ulna and ulnar notch on radius
- pronation/supination: linked motion
- IO membrane transmits forces: at prox. end only 20% through radius, at distal end, 80% is through radius
- fracure at one end may lead to dislocation at other end
What are the features (including blood/nerve supply) to proximal radioulnar joint?
- between head of radius and radial notch of ulna
- pivot, synovial joint
- w/in elbow joint capsule
- sacciform recess
BS: branches of deep radial and radial arteries
NS: median, musculocutaneous, radial
What are the ligaments of the proximal radioulnar joint?
- Annular ligament
- Quadrate ligament/oblique ligament: only ligament that makes contact with radius at the neck
- IO membrane
What are the features (+ bld & n’ supply) of the distal R-U joint?
- between head of ulna and ulnar notch on radius
- pivot, synovial
- ligaments: anterior & posterior
- articular disc: triangular ligament
- sacciform recess
Blood: anterior, posterior IO arteries
Nerve: median & radial IO nerves
What are the movements at the R-U joints?
- pronation/supination, working along with F/E
- midprone position is most stable
What muscles move R-U joints?
Pronation
- pronator teres
- pronator quadratus
- assisted by: FCR, PL, brachioradialis (in midprone position)
Supination
- supinator
- biceps brachii
- assisted by: EPL, ECRL
What occurs during dislocation of proximal R-U joint?
- Annular ligament lax in children
- radial head is displaced
- muscle pulls radial head superiorly
- reduction: supinate forearm, push proximally, joint in flexion
- normal
- subclinical subluxation (head of radius pulled out of annular ligament but hasn’t moved out of place)
- subluxation
- dislocation
What are the clinical considerations at the H-U and R-U joints?
Bursitis
Epicondylitis
Avulsion fractures:
- medial epicondyle of humerus
- olecranon process of ulna
- coronoid process of ulna
- styloid process of ulna
Supracondylar fracture of humerus
-radius artery endangered (Volkmann’s ischemic contracture)
