Elbow and Forearm

Question 1

describe the AoR of the elbow joint

Answer 1

1. axis just below the epicondyles
2. does not follow a cardinal plane but
3. 1 degree of freedom: flexion and extension

Question 2

what gives the elbow joint its stability?

Answer 2

bony configuration and three articulations in closed pack position

Question 3

what provides medial elbow stability?

Answer 3

anterior, posterior, and transverse MCLs

Question 4

what is usually damaged in the elbow in throwing injuries?

Answer 4

MCL - tommy john

Question 5

what provides lateral stability at the elbow?

Answer 5

LCL = radial collateral + lateral ulnar collateral + annular

Question 6

what is nursemaids elbow?

Answer 6

proximal radius pulled from annular ligament

Question 7

what are the arthrokinematics of open chain elbow flexion?

Answer 7

1. concave ulna on convex trochlea
2. concave radius on convex capitulum

Question 8

what are the arthrokinematics of closed chain elbow flexion?

Answer 8

1. pull up!
   
   1. convex trochlea on concave ulna
   2. convex capitulum on concave radius

Question 9

what is physiologic cubitus valgus?

Answer 9

13-15 degrees

females > males by 6 degrees

Question 10

how do individuals with a C7 or above injury extend the elbow?

Answer 10

shoulder flexion and ER with the hand planted

Question 11

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?

Answer 11

to transmit forces proximally through the UE with compression

Question 12

how does the IOM working during a distracting force?

Answer 12

it doen’t do much

pulling on the radius requires brachioradialis strength but slackens the IOM

Question 13

what are the arthrokinematics of pronation and supination?

Answer 13

1. proximal RU
   
   1. convex radius on concave ulna
2. distal RU
   
   1. concave radius on convex ulna

Question 14

what are the arthrokinematics of full pronation at the distal RU?

Answer 14

concave radius on convex ulna

Question 15

why is elbow flexion usually spared in many injuries?

Answer 15

variety of innervation to each elbow flexor muscle

Question 16

which muscle is the workhorse of elbow flexion, why?

Answer 16

brachialis - can elbow flex in any position

Question 17

which muscle flexes in a neutral position?

Answer 17

brachioradialis

Question 18

which muscle of the elbow is most active in resisted rapid movements?

Answer 18

brachioradialis

Question 19

where does maximum flexor force occur?

Answer 19

70-90 elbow flexion

Question 20

when do elbow flexors generate the most internal torque? why?

Answer 20

90 degrees flexion b/c toque is greatest due to distance from AOR

Question 21

torque output and elbow flexor force are related to LT and IMO how?

Answer 21

• torque output
  
  • r/t LT and IMO
• elbow flexor force
  
  • r/t LT only

Question 22

what is the workhorse of the triceps?

Answer 22

middle head

Question 23

what elbow extensor is active in low level force requirements

Answer 23

anconeus - recruited first

Question 24

when do elbow extensors produce max torque?

Answer 24

90 deg elbow flexion

Question 25

what is the biggest influence on elbow extensors? LT relationship or IMO?

Answer 25

LT (physiologic)

not IMO (biomechanical)

Question 26

what are synergists of pushing a door open?

Answer 26

triceps and anterior deltoid

Question 27

when is the biceps able to produce the most supinator force? why?

Answer 27

90 degrees elbow flexion - full biceps force perpendicular to AOR in supination

Question 28

what are the main pronators?

Answer 28

PT and PQ

Question 29

why does forceful supination require triceps activity?

Answer 29

triceps helps maintain LT relationship at the biceps

Question 30

what muscles are firing and how during forceful supination? (2)

Answer 30

• supinators concentrically (biceps especially)
• triceps isometrically

Question 31

how do you apply autogenic inhibition in the clinic?

Answer 31

fire the tight to relax the tight

Question 32

how do you apply reciprocal inhibition in the clinic?

Answer 32

max fire the opposite group to relax the target, tight group