Elbow Flashcards
Carrying angle
- frontal plane
- affected by a person’s height, gender, and age
- avg for females: 13-16*
- avg for males: 11-14*
Medial epicondyle
- more prominent than lateral
- point of attachment for common flexor tendon, pronator teres, and ulnar collateral ligament
Lateral epicondyle
-attachment for supinator, radial collateral ligament, and extensor muscles
Joint mechanics during elbow flexion
- ulna locks into coronoid fossa of distal humerus
- radial head articulates with capitellum - restrained by radial fossa on anterolateral side of humerus
Capitellum and trochlea placement
Capitellum=lateral
Trochlea = medial
Radius
- concave
- annula ligament surrounds radial head and attaches to radial notch of ulna
- 2408 of radial head’s margin articulates with ulna
Ulna
- primary source of bony stabilization at elbow
- trochlear notch articulates with trochlea of humerus
Oblique cord
- inserts into the radial tuberosity
- thickening of fascia of supinator and assists with limiting supination
Humeroulnar articulation
- medial side
- medial lip of trochlea and trochlear notch of ulna
- olecrenon is posterior articulation
- contributes to flexion and extension
Humeroradial articulation
- lateral aspect
- concave radial head, capitellum of humerus, prominent tubercle/groove on lateral lip of trochlea of humerus capitellum
- contributes to all planes of otion
- resists valgus stress
- radial head is essential to elbow stability in the absence of collateral ligament integrity or distal radioulnar stability
Proximal radioulnar articulation
- radial head, annular ligament ring, radial fossa of ulna
- optimal motion is 70* pronation and 80* supination
- interosseous membrane - essential for distribution of loads and communication between the PRUJ to the distal radioulnar joint
- peak strain on interosseous membrane is during neutral forearm rotation
Distal radioulnar articulation
- compound joint with PRUJ
- distal end of ulna, radius, joint capsule, triangular fibrocartilage complex (TFCC)
- pivot and glide allows for 70* pronation, 80* supination
Full pronation ariticulation
-volar/anterior ligament of TFCC is taut
Full supination articulation
-dorsal/posterior ligament of TFCC is taut
Elbow capsule
- surrounds all 3 articulations (humeroulnar, humeroradial, PRUJ)
- anterior capsule taught in full extension
- posterior capsule taut in full flexion
- capsule demonstrates greatest extensibility bw 70-90* flexion
- blends with annular ligament and thickens on medial and lateral sides to form collateral ligaments
Ulnar (medial) collateral ligament complex
3 parts - anterior, posterior, transverse
- origin is posterior to elbow joint
- becomes taut with flexion
- anterior: strongest of the 3. Attaches from anterior medial epicondyle to medial coronoid process
- anterior band: taught from extension to 60* flexion
- posterior band: taut from 60-120* flexion
- anterior part is greatest restraint to valgus stress
- Posterior: fan like thickening. Most taut at 90* flexion. restrains maximal gapping during pronation
- Transverse (oblique): less impactful on elbow stability.
Radial (lateral) collateral ligament
- 4 parts: AL, radial portion, ulnar portion, variably present accessory portion
- primary role in elbow stabilization
- taut through flexion and extension
- tension increased during supination
- radial portion: taut throughout flexion and extension
- ulnar portion: most well known for posterolateral rotatory instability - taut in flexion and ext and provides stability to humeroulnar joint
- accessory portion - assists in stabilizing AL against varus stress
Biceps brachii
- long and short head
- innervated by musculocutaneous
- distal attachment a common biceps tendon at radial tuberosity
- elbow flexion and supination
Brachialis
- beneath biceps
- proximal attachment from anterior humerus and distal attachment on ulna tuberosity and coronoid process
- mechanical disadvantage for great force in flexion
Brachioradialis
- greatest mechanical advantage for elbow flexion
- proximal attachment at lateral supracondylar ridge
- distal attachment at styloid process of the radius
Triceps brachii
- 3 heads: long, lateral, medial
- extension of the elbow
- long head attaches at infraglenoid tubercle on scapula
- lateral attaches from proximal posterior humerus
- medial attaches at posteromedial humerus
- common distal attachment at olecrenon
Anconeus
- from lateral epicondyle to posterolateral olecrenon
- joint stabilizer
Common extensor tendon
-extensor carpi radialis brevis
-extensor digitorum
-extensor digiti minimi
-extensor carpi ulnarus
(lateral to medial order)
-radial nerve innervation
Supinator
- -beneath extensor muscle group
- 4 proximal attachments: lateral epicondyle, RCL, AL, crista supinatoris o fulna on olecrenon
- supination is primarily accomplished by biceps and less by supinator
Pronator teres
- strong pronator of forearm, but weak elbow flexor
- 2 proximal attachments; medial epicondyle and coronoid process
- resist valgus stress
flexor carpi radialis
- medial to pronator
- attachment with common flexor tendon
- flexion and radial deviation
Flexor carpi ulnaris
- common flexor tendon
- 2 heads that are split by the ulnar nerve
Radial nerve
C5-8
Ulnar nerve
C8-T1
Median Nerve
C5-6, C8-T1