Elbow and Forearm Flashcards
describe the AoR of the elbow joint
- axis just below the epicondyles
- does not follow a cardinal plane but
- 1 degree of freedom: flexion and extension
what gives the elbow joint its stability?
bony configuration and three articulations in closed pack position
what provides medial elbow stability?
anterior, posterior, and transverse MCLs
what is usually damaged in the elbow in throwing injuries?
MCL - tommy john
what provides lateral stability at the elbow?
LCL = radial collateral + lateral ulnar collateral + annular
what is nursemaids elbow?
proximal radius pulled from annular ligament
what are the arthrokinematics of open chain elbow flexion?
- concave ulna on convex trochlea
- concave radius on convex capitulum
what are the arthrokinematics of closed chain elbow flexion?
- pull up!
- convex trochlea on concave ulna
- convex capitulum on concave radius
what is physiologic cubitus valgus?
13-15 degrees
females > males by 6 degrees
how do individuals with a C7 or above injury extend the elbow?
shoulder flexion and ER with the hand planted
aside from binding the radius and the ulna and serving as an attachment point for hand muscles, what is the major function of the IOM?
to transmit forces proximally through the UE with compression
how does the IOM working during a distracting force?
it doen’t do much
pulling on the radius requires brachioradialis strength but slackens the IOM
what are the arthrokinematics of pronation and supination?
- proximal RU
- convex radius on concave ulna
- distal RU
- concave radius on convex ulna
what are the arthrokinematics of full pronation at the distal RU?
concave radius on convex ulna
why is elbow flexion usually spared in many injuries?
variety of innervation to each elbow flexor muscle
which muscle is the workhorse of elbow flexion, why?
brachialis - can elbow flex in any position
which muscle flexes in a neutral position?
brachioradialis
which muscle of the elbow is most active in resisted rapid movements?
brachioradialis
where does maximum flexor force occur?
70-90 elbow flexion
when do elbow flexors generate the most internal torque? why?
90 degrees flexion b/c toque is greatest due to distance from AOR
torque output and elbow flexor force are related to LT and IMO how?
- torque output
- r/t LT and IMO
- elbow flexor force
- r/t LT only
what is the workhorse of the triceps?
middle head
what elbow extensor is active in low level force requirements
anconeus - recruited first
when do elbow extensors produce max torque?
90 deg elbow flexion
what is the biggest influence on elbow extensors? LT relationship or IMO?
LT (physiologic)
not IMO (biomechanical)
what are synergists of pushing a door open?
triceps and anterior deltoid
when is the biceps able to produce the most supinator force? why?
90 degrees elbow flexion - full biceps force perpendicular to AOR in supination
what are the main pronators?
PT and PQ
why does forceful supination require triceps activity?
triceps helps maintain LT relationship at the biceps
what muscles are firing and how during forceful supination? (2)
- supinators concentrically (biceps especially)
- triceps isometrically
how do you apply autogenic inhibition in the clinic?
fire the tight to relax the tight
how do you apply reciprocal inhibition in the clinic?
max fire the opposite group to relax the target, tight group
