Elbow/Forearm

Question 1

Which joints make up the elbow?

Answer 1

Humeroulnar and humeroradial joints

also proximal radioulnar joint but that’s not part of the hinge

Question 2

What is the carrying angle?

Answer 2

Angle between long axis of humerus and long axis of forearm, should be about 15 degrees.

Question 3

Normal elbow ROM

Answer 3

5 degrees hyperextension to 145 degrees of flexion

Question 4

Arthokinematics of humeroulnar joint

Answer 4

concave trochlear notche of ulna on trochlea of humerus

Flexion: concave notch rolls and slides on trochlea

Question 5

Arthokinematics of humeroulnar EXTENSION

Answer 5

Roll and glide POSTERIORLY

Question 6

Arthokinematics of humeroulnar FLEXION

Answer 6

Roll and glide ANTERIORLY

Question 7

Arthrokinematics of humeroradial joint

Answer 7

Fovea of radial head with capitulum of humerus

-concave radial head on convex capitulum

Question 8

Arthokinematics of humeroradial FLEXION

Answer 8

anterior roll, anterior glide

Question 9

Arthokinematics of humeroradial EXTENSION

Answer 9

posterior roll, posterior slide

Question 10

Articulating surfaces of proximal radioulnar joint

Answer 10

ulnar radial notch and annular ligament

Question 11

Articulating surfaces of distal radioulnar joint

Answer 11

Ulnar notch of radius, articular disc/head of ulna

Question 12

Triangular Fibrocartilage complex

Answer 12

Ulnocarpal joint beneath distal radioulnar joint

Question 13

Where do supination and pronation occur?

Answer 13

Both radioulnar joints

Humeroradial joint

Question 14

Normal pro/sup

Answer 14

75 pro

85 sup

Question 15

Arthokinematics of proximal radioulnar joint

Answer 15

Radial head (convex) rotates in ring on radial notch (concave) – not normal arthrokinematics here

Question 16

Arthokinematics of distal radioulnar joint

Answer 16

Concave radius on convex ulna– roll/glide in direction of ulnar head motion

Question 17

In supination, roll and glide occur

Answer 17

laterally

Question 18

In pronation, roll and glide occur

Answer 18

medially

Question 19

Pronation/Supination occur in closed chain as a function of…

Answer 19

Glenohumeral IR/ER

Question 20

Name the elbow flexors and where they are most effective.

Answer 20

Biceps: Supination
Brachialis: Generates most force. Pronation.
Brachioradialis: Neutral. Effective in rapid movements.

Question 21

Elbow extensors

Answer 21

Triceps, Anconeus

Question 22

Max force generation of triceps

Answer 22

At about 90 degrees.

Question 23

Elbow extension is often performed with…

Answer 23

Shoulder flexion

Question 24

Why does elbow extension occur with shoulder flexion?

Answer 24

Anterior deltoid works synergistically to oppose shoulder extension torque from triceps

Question 25

Primary and secondary supinators

Answer 25

Primary: Supinator, Biceps
Secondary: Radial wrist extensors, EPL, ExtIn, Brachioradialis IF IN PRONATION

Question 26

Primary pronators?

Secondary pronators?

Answer 26

Primary = Pronator Teres/Quadratus

Secondary: FCR, PL, Brachioradialis IF IN SUPINATION

Question 27

Describe the Law of Parsimony.

Answer 27

Smaller one-joint muscles are recruited first for lower power tasks. If higher power functions needed, multi-joint muscles will kick in and other muscles will need to kick in to negate that muscle’s other actions.