Elbow

Question 1

where does most of the structural stability come from

Answer 1

humero-ulnar joint

Question 2

humero-ulnar joint is considered a

Answer 2

modified hinge joint. mostly flexion/extension. slight axial rotation of the ulna

Question 3

what is a normal carrying angle?

Answer 3

13 plus or minus 6

Question 4

excessive carrying angle

Answer 4

greater than 20

Question 5

cubital varus

Answer 5

no carrying angle, (gunstock deformity)

Question 6

cubital valgus

Answer 6

carrying angle

Question 7

Ulnar collateral ligament posterior fibers limit..

Answer 7

valgus, extension, flexion

Question 8

UCL has three parts

Answer 8

anterior, posterior, transverse

Question 9

anterior part of UCL do what

Answer 9

limit valgus stress, excessive flex and ext.

Question 10

radial collateeral ligament

Answer 10

limits varus, external rotation

Question 11

lateral ulnar collateral ligament

Answer 11

limits varus, external rotation, flexion

Question 12

annular ligament limits

Answer 12

radial distraction, external rotation (like a sleeve)

Question 13

most common injury to ligaments of elbow

Answer 13

ulnar collateral ligament rupture

Question 14

both humero radial and humero ulnar joints are what arthrokinematics

Answer 14

concave on convex. roll and slide in same motion

Question 15

which joint is the load bearing through the hand

Answer 15

radiocarpal joint

Question 16

what enables load sharing of compression with ulna

Answer 16

interosseous membrane

Question 17

what is the primary stabilizer of the distal radio-ulnar joint

Answer 17

triangular fibrocartilage complex (TFCC)

Question 18

distal radio-ulnar joint arthrokinematix

Answer 18

concave on convex SAME

Question 19

proximal radio ulnar joint

Answer 19

convex on concave opposite

Question 20

what dertermines force potential

Answer 20

PCSA

Question 21

what determines mechanical advantage

Answer 21

moment arm

Question 22

How many joints does the elbow contain

Answer 22

4

Question 23

what four joints make up the elbow

Answer 23

humeroulnar
humeroradial
proximal radioulnar
distal radio-ulnar jt

Question 24

most structural stability comes from which elbow jt

Answer 24

humero-ulnar jt

Question 25

what gender has a larger carrying angle

Answer 25

women

Question 26

what is considered excessive cubital valgus

Answer 26

greater than 20

Question 27

cubital varus

Answer 27

gunstock deformity - none or negative carrying angle | hand is medial - adducted

Question 28

ulnar collateral lig ( anterior fibers)

Answer 28

stability lig | taut with valgus stress, excessive extension, excessive flexion

Question 29

ulnar collateral lig (posterior fibers)

Answer 29

limits valgus stress | taut at end range of flexion

Question 30

valgus stress on the elbow

Answer 30

pushes elbow in medially

Question 31

varus stress on the elbow

Answer 31

pushes elbow out

Question 32

radial collateral lig

Answer 32

limit varus stress and external rot

Question 33

lateral ulnar collateral lig

Answer 33

humerus to ulna | good for stabilizing

Question 34

annular ligament

Answer 34

circular limits radial distraction (pulling out) and external rot(supination) pulling on hand (holding child and swinging them)

Question 35

what lig is likely to rupture with a nordic ski pole stuck

Answer 35

ulnar collateral

Question 36

most common injury to elbow

Answer 36

ulnar collateral ligament rupture

Question 37

FOOSH

Answer 37

fall on outstretched hand

Question 38

what kind of stress is seen in a UCL rupture

Answer 38

valgus

Question 39

contracture

Answer 39

loss of ROM, no mobility at the jt because everything is shortened

Question 40

humero-ulnar arthrokinematics

Answer 40

concave trochlear notch slides and rolls on convex trochlea | same direction

Question 41

what happens to radius and ulna during pronation

Answer 41

distal end of radius crosses over fixed ulna

Question 42

primary stabilizer of the distal radioulnar jt

Answer 42

triangular fibrocartilage complex

Question 43

what holds ulnar head firmly against ulnar notch of radius in pronation/supination

Answer 43

TFCC (common site for tears) | provides stability of ulna so it is not just flopping around

Question 44

radial-ulnar arthrokinematics of supination and pronation

Answer 44

distal - concave ulnar notch of radius rolls and slides over convex ulna (same) proximal - radial head rotates in the annular ligament/radial notch ulna (convex on concave)

Question 45

which flexor muscle is big on control

Answer 45

biceps brachii (2jt muscle)

Question 46

what is the primary elbow flexor

Answer 46

brachialis (1 jt) | biggest PCSA

Question 47

which elbow flexor has the biggest mechanical advantage

Answer 47

brachioradialis (1 jt) | highest moment arm

Question 48

why will shoulder in extension give you greater elbow flexion force potential

Answer 48

slower velocity is higher force in concentric conditions

Question 49

what has the greatest force potential and greatest mechanical advantage in the elbow extensors

Answer 49

triceps

Question 50

what is the first extensor to initiate

Answer 50

anconeus (stays activates as you go through extension) medial head of tri next (workhorse muscle) lateral and long head last ( reserve mm for maximal extension force)

Question 51

when is supination strongest

Answer 51

shoulder external rotation and 90 degrees elbow flexion

Question 52

what does 90 degrees of elbow flexion do for supination

Answer 52

optimizes biceps brachii (strong supinator)

Question 53

supinators produce ___ more torque than pronators

Answer 53

25% a left hand screwdriver would have to do pronation to tighten the screw (fatigue quicker)