Elbow Anatomy Flashcards
Elbow joint
hinge joint
- radiocapitellar joint (humeroradial)
- ulnotrochlear joint (humeroulnar)
- proximal radioulnar joints
elbow ligaments
lateral collateral ligament (radial collateral ligament -RCL): lateral epicondyle to radius, resists varus forces (pushing elbow out), common with tennis; prevents subluxation and dislocation
medial collateral ligament (ulnar collateral ligament -UCL): medial epicondyle to ulna, resists valgus forces (pushing elbow in), common with throwing (baseball)
[anterior bundle most important bundle of UCL]
annular radial ligament: stretches across radial head, prevents anterior displacement radius; nursemaid elbow when radial head subluxed out of ligament and ov erlying rather than underlying; common when child’s hand yanked up; Tx is to reduce it
common extensor tendon and common flexor tendon runs superficial to RCL and UCL, respectively
Elbow flexion (muscles, inn.)
Biceps brachii: C5-6, upper trunk, lateral cord, musculocutaneous n.
- supinator (most powerful) and elbow flexor
- *Brachialis**: C5-6, upper trunk, lateral cord, musculocutaneous n.
- chief elbow flexor, pure elbow flexor
- implications for botox injections if wanting to maintain supination and relieve flexor spasticity
Brachioradialis; C5-6, upper trunk, posterior cord, radial n. (BELOW spiral groove)
Pronator teres: C6-7, upper and middle trunks, lateral cord, median n.
Elbow extension (muscles, inn.)
Triceps: C6-8, all 3 trunks, posterior cord, radial n. (innervated ABOVE spiral groove)
Anconeus: C6-8, all 3 trunks, posterior cord, radial n. (innervated ABOVE spiral groove)
midshaft humeral fractures may damage radial n. → wrist drop, finger drop, impaired radial n. muscles at elbow and below
- *triceps and anconeus preserved because already innervated (above spiral groove)**
- *HIGH YIELD**
Forearm supination (muscles, inn.)
Biceps brachii: C5-6, upper trunk, lateral cord, musculocutaneous n.
- supinator (most powerful) and elbow flexor
Supinator: C5-6, posterior cord, radial n., PIN-posterior interosseous n. (pure motor n. from median n.)
Forearm pronation (muscles, inn.)
Pronator teres: C6-7, upper and middle trunks, lateral cord, median n.
Pronator quadratus: C7-8-T1, middle and lower trunks, medial and lateral cords, median n., AIN-anterior interosseous n. (pure motor n. from median n.)
Common flexor tendon
medial epicondyle humerus (golfer’s elbow/medial epicondylitis)
pronator teres (PT): C6-7, upper and middle trunks, lateral cord, median n.
flexor carpi radialis (FCR): C6-7, upper and middle trunks, lateral cord, median n.
palmaris longus
flexor carpi ulnaris (FCU): C8-T1, lower trunk, medial cord, ulnar n.
flexor digitorum superficialis (FDS): C7-8, middle and lower trunks, medial and lateral cords, median n.
PIP flexion, attaches to proximal phalanx of digits 2-5
flexor digitorum profundus (FDP): C7-8-T1, middle and lower trunks, medial cord, AIN/ulnar n.
“so profound that it requires 2 nerves to innervate it (median and ulnar)
splits around FDS tendon, attaches to distal phalanx for DIP flexion digits 2-5
[FPL originates off radius, not part of common flexor tendon; like FDP to digit 1 and flexes distal phalanx of thumb; consider like “FDP 1”]
Common extensor tendon
located at lateral epicondyle of humerus (tennis elbow/lateral epicondylitis)
extensor carpi radialis longus and brevis (ECRL/ECRB)
ECRB most commonly inflamed w micro tears w tennis elbow
C6-8, all 3 trunks, posterior cord, radial n. (innervated ABOVE spiral groove)
extensor digitorum (ED/EDC): C7-8, middle and lower trunk, posterior cord, radial n., PIN
Anconeus: C6-8, all 3 trunks, posterior cord, radial n. (innervated ABOVE spiral groove)
Supinator
extensor carpi ulnaris (ECU): C7-8, middle and lower trunk, posterior cord, radial n., PIN
Humeral shaft fracture
FOOSH
radial nerve injury - spiral groove
impaired wrist drop
Dx: XR, PE
Tx: splinting usually
Distal humerus fracture
trauma
Dx: XR, PE, good neuromuscular exam
radial, median, ulnar ns. run through
Tx: if displaced - ORIF, if non displaced - splint
Olecranon fx
FOOSH
ulnar n. injury
Dx: XR, PE
Tx: splinting if non displaced, ORIF if displaced
Radial head fx
FOOSH
Dx: XR, PE
Tx: splint or ORIF
Valgus extension overload syndrome (VEO)
repetitive valgus extension forces (baseball players)
posteromedial elbow pain worse w pitching and VEO test
VEO test: flex elbow, extend it while applying valgus stress (stimulates pitching)
Dx: XR (olecranon osteophytes / loose bodies may be seen)
Tx: surgery to remove above, fix pitching mechanics to reduce valgus extension forces
Little leaguer’s elbow: repetitive valgus stress → traction apophysitis medial epicondyle growth plate → osteochondritis dessicans of capitellum
apophysis: local spot on bone where tendons attach
osteochondritis dessicans typically just happens at capitellum → lateral elbow pain
Osteochondrosis of elbow
poor blood supply to epiphysis → aseptic necrosis of capitellum epiphysis
lateral elbow pain worse w activity, improved w rest
usually in children
Dx: XR - patchy lucencies in capitellum
Tx: splinting, gradual increase activity
Elbow dislocation
FOOSH
most common dislocation in children
vs shoulder w adults
usually posterior dislocation; ulna goes posteriorly
Dx: XR, PE, neurovascular
Tx: closed reduction → splinting → gradual activity
Nursemaid elbow
radial head subluxes out of annular ligament
d/t yanking up on child’s arm by the hand
Dx: XR, neurovascular exam
Tx: reduction (hyperpronate arm or supinate while flexing elbow)
UCL sprain
excessive valgus force → anterior bundle UCL tearing (sprain)
medial elbow pain w laxity on valgus stress testing
Dx: PE, XR (calcification, cortical irregularities, spurs on UCL)
U/S valgus stress test → increased laxity
Tx: RICE, PT, surgery (Tommy John)-if high level athlete for reconstruction and prevention valgus stress
RCL sprain
excessive varus force → tearing (sprain) RCL
pain at lateral elbow worse w varus stress testing
Dx: PE, XR, U/S (laxity)
Tx: RICE, PT, surgery
Olecranon bursitis
repetitive force → inflammation of olecranon bursa
sometimes associated w gout, pseudogout, RA
huge pouch develops bc little tissue to restrict expansion
Dx: PE, consider aspiration/culture if infxn suspected
Tx: RICE, elbow pad, aspiration
often recurs so if force required bc work etc. give elbow pads
Lateral epicondylitis (tennis elbow)
usually ECRB
pain at common extensor tendon origin at lateral epicondyle
Dx: PE, PT
- *Cozen test**: pain w palpation origin of CET w resisted wrist extension
- *Mill’s test**: pain w elbow extension while flexing and radially deviating wrist
Tx: RICE, PT, splinting, U/S steroid injection superficial to tendon (not inside d/t rupture), tenotomy (U/S needle in and out of tendon to create bleeding and inflammation for growth factors to heal), regenerative therapy (PRP, prolotherapy)
Tennis players: need to increase grip size, decrease string tension to below 55lbs (reduce stress to CET), play on slow court e.g. clay, correct technique
Medial epicondylitis (golfer elbow)
CFT inflammation d/t repetitive overuse, valgus stresses → microtearing of CFT (golfers, pitchers)
Dx:
reverse Cozen: pain w resisted wrist flexion
reverse Mills: pain w extension while palpating CFT origin
Distal biceps tendonitis/tear
repetitive overload → inflammation/microtears
pain over antecubital fossa, worse w loading (curls
heavy lifting → rupture occurs → sudden onset swelling/bruising
Dx:
Hood test: hook distal biceps tendon out of anterior elbow
XR: r/o avulsion of bone; requires surgery if avulsion or ruptured
Triceps tendonitis/tear
posterior elbow/triceps pain d/t overuse, worse w resisted elbow extension
sudden eccentric force → may cause avulsion → requires surgery
