Elbow Flashcards
(28 cards)
Humeroulnar Jt
Flexion and extension (bones)
primarily sliding motion
Flexion
- ulna slides along trochlea until coronoid process enters coronoid fossa
Extension
- ulna slides until olecranon process enters olecranon fossa
trochlea only contacts deepest portion of notch when jt. Is heavily loaded
Humeroradial jt.
Flexion and Extension (bones)
primarily sliding motion (CVS)
Full flexion
- rim of radial head slides into radial fossa
Full extension
- No contact btwn articulating radial head and capitulum (nonloaded/NWBing)
What plane does pronation and supination happen in ?
TRANSVERSE PLANE
Elbow Jt. Capsule and Membrane
Capsule
- large and loose
- weaker anteriorly and posteriorly
- reinforced laterally and medially by collateral ligaments
Synovial Membrane
- folds in membrane allow expansion for full ROM
- can be inflamed or hypertrophied causing pain
Valgus & Valgus Force
Valgus: lateral projection of distal segment of bone or joint
Valgus force: creates tension on medial aspect of elbow and increases compression at lateral jt
- pushing lateral elbow or medial wrist
- stretches Ulnar Collateral Ligament
Varus and Varus Force
Varus: medial projection of distal segment
Varus force: creates tension on lateral aspect of elbow and increases compression medially
- pushing on medial elbow or lateral wrist
- stretches Radial Collateral Ligament
Ulnar (medial) collateral ligament complex
Overall function
- stabilizes against valgus forces at medial elbow
- limits Hyperextension
- guides jt. Motion throughout flexion ROM
- some resistance to longitudinal distraction of jt. Surfaces
Anterior bundle
- resists valgus stress from 20-120 degrees of elbow flexion
Posterior bundle
- less significant role in valgus stability
Transverse (oblique) bundle
- aka Cooper’s ligament
- approximation of jt. Surfaces
Radial (lateral) Collateral Ligament Complex
Overall function
- stabilizes elbow against Varus forces
- stabilizes against combined Varus and supination
- reinforces HR jt -> some resistance to longitudinal distraction
- maintains posterolateral rotary stability
- stabilizes radial head for rotation
Lateral (radial) collateral lig
- resists Varus stress at elbow
- reinforces HR jt
- assists in resisting longitudinal distraction
Lateral ulnar collateral lig
- Secondary restraint to combined forced Varus and supination stresses
- assists in resisting Varus stress
Annular lig (anniversary ring)
- holds radial head against ulna @ PRUJ
- resists distraction of radius
What is the Normal Carrying Angle of the Elbow?
Forearm typically lies slightly LATERAL to humerus when elbow is fully extended in anatomic position
Normal range: 8-15 degrees
Female carrying angle greater than males (because our hips dont lie)
What is Cubital (cubitus) Valgus
EXCESSIVE carrying angle greater than 15 degrees
What is Cubital (cubitus) Varus
REDUCED carrying angle less than 5 degrees
Aka gunstock deformity
- results from a malunion following a supracondylar fracture of humerus
Carrying Angle: Flexion of Elbow
Typical Carrying Angle
- Forearm comes to rest in line with humerus
Cubital Valgus
- Forearm comes to rest medial to humerus
Cubital Varus
- Forearm comes to rest lateral to humerus
Elbow Flexors
Brachialis: mobility muscle
best when pronated
- insertion is CLOSE to axis of rotation
- large CSA
- MA is greatest @ ~ 100 degrees of elbow flexion
Biceps brachii: mobility muscle
best when supinated
- inserts CLOSE to axis of rotation
- shoulder position impacts force production
- MA is greatest @ ~ 80-100 degrees flexion
-> MA decreases as elbow moves closer to full extension making it less effective flexor
Brachioradialis: stability muscle
best when in neutral position
- insertion is FARTHER from axis of rotation
- joint compression
- Peak MA 100-200 degrees elbow flexion
-> small CSA
- activity increases when speed of flexion increases
Elbow Extensors
Triceps brachii: primary extensor
- long head force ability impacted by shoulder position impacts
-> not medial and lateral heads
- stabilizer and synergist
- max torque @ ~90 degrees of elbow flexion
Anconeus
- assists elbow extension
- STABLIZER
Factors Impacting Flexion/Extension @ Elbow
- Type of motion (active or passive)
- passive flexion is greater than active flexion - Position of the forearm (pro/sup)
- flexion will be greater when forearm is supinated - BMI
- flexion ROM is less with higher BMI due to tissue approximation - Position of shoulder
- active or passive insufficiency of 2 jt muscles can impact elbow motion
Factors Contributing to Stability @ Elbow Jt.
- Configuration of jt. Surfaces
- inherent articular stability at end range flex and ext
-> less bony contact during extension
-> not locked in tightly (not congruent surfaces) - Ligaments
- Joint capsule
- Active and passive tension in muscles crossing the jt
- tight muscles limit opposing motion -> not able to stretch
- contribute to stabilization via compression and co contraction
- co contraction of muscles at elbow assists in creating a stable base for forceful motions of wrist and fingers
Ligaments @ PRUJ
- annular
- quadrate
- oblique cord
Annular ligament
- forms a ring encircling the radial head
- holds radial head in place during pron/sup
Quadrate Ligament
- limits spin of radial head in sup and pro
Oblique cord
- potentially assists in preventing separation of radius and ulna
What does the TFCC do?
-primary stablizer of DRUJ
- Enhances jt congruity
- reinforces ulnar aspect of wrist
- forms part of concavity of Radiocarpal jt
- assits in transfer of compressive force
-> ~20 % of total compressive force though wrist passes through disc of TFCC
Radioulnar Motion (degrees)
(During flexion and extension)
Total ROM ~ 150 degrees
Elbow fully flexed: (more supination)
~ 90 degrees supination
~ 60 degrees pronation
Elbow fully extended: (more pronation)
~ 100 degrees pronation
~ 50 degrees supination
ARTHROKINEMATICS @ PRUJ
Ulna and Radius
Flexion and Extension
(Open chain)
FES CVS
Flexion
Ulna: slides and rolls ventral/anterior/superior direction
Radius: slides and rolls ventral/anterior/superior direction
Extension
Ulna: slides and rolls dorsal/posterior/inferior
Radius: slides and rolls dorsal/posterior/inferior
ARTHROKINEMATICS @ PRUJ
Pronation and Supination
NWBing/open chain
PSO VCO
Pronation
Radial head primarily spins on ulna
- anterior roll, posterior slide of radius on ulna
Supination
Radial head primarily spins on ulna
- posterior roll, anterior slide of radius on ulna
ARTHROKINEMATICS @ DRUJ
Pronation and Supination
NWBing/ Open Chain
CVS
Pronation
- radius rolls and slides anteriorly on ulna
Supination
- radius rolls and slides posteriorly on ulna
ulnar notch of radius is concave
ARTHROKINEMATICS @ PRUJ
Pronation and Supination
WBing/ Closed Chain
CVS
Pronation
- ulna rotate anteriorly around radial head
Supination
- ulna rotate posteriorly around radial head
ARTHROKINEMATICS @ DRUJ
Pronation and Supination
WBing/ Closed Chain
VCO
Pronation
- ulna rolls ventrally/palmarly and slides dorsally
Supination
- ulna rolls dorsally and slides ventrally/palmarly
