6.2 Elbow Forearm

Question 1

What are the main bones forming the elbow and forearm complex?

Answer 1

The humerus, ulna (medial), and radius (lateral).

Question 2

What are the three key articulations of the elbow joint complex?

Answer 2

Humeroulnar joint, humeroradial joint, and proximal radioulnar joint.

Question 3

What joints make up the forearm complex?

Answer 3

Proximal and distal radioulnar joints.

Question 4

What type of joint is the elbow considered to be?

Answer 4

A modified hinge joint that allows primarily flexion and extension with slight rotation and side-to-side movement.

Question 5

Which structures articulate at the humeroulnar joint?

Answer 5

The trochlea of the humerus and the trochlear notch of the ulna.

Question 6

Which structures articulate at the humeroradial joint?

Answer 6

The capitulum of the humerus and the head of the radius.

Question 7

Which structures articulate at the proximal radioulnar joint?

Answer 7

The radial head and the radial notch of the ulna (within the annular ligament).

Question 8

Which structures articulate at the distal radioulnar joint?

Answer 8

The head of the ulna and the ulnar notch of the radius.

Question 9

What is the functional purpose of the elbow joint?

Answer 9

To provide mobility for positioning the hand and stability for handling loads.

Question 10

Describe the general structure of the ulna.

Answer 10

Thick and expanded proximally (olecranon process), thinner distally.

Question 11

Describe the general structure of the radius.

Answer 11

Thin proximally, thicker distally to support the wrist.

Question 12

What bony structure forms the point of the elbow?

Answer 12

The olecranon process of the ulna.

Question 13

What forms the trochlear notch of the ulna?

Answer 13

The olecranon process and coronoid process together.

Question 14

What is the carrying angle?

Answer 14

The angle between the humerus and the forearm due to the trochlea sitting more distal than the capitulum.

Question 15

What does the carrying angle allow functionally?

Answer 15

Allows the forearm to clear the hips during arm swing and for smooth flexion/extension.

Question 16

What is the axis of rotation for forearm pronation and supination?

Answer 16

A line extending from the radial head to the ulnar head.

Question 17

What motion occurs at the proximal radioulnar joint during pronation/supination?

Answer 17

Rotation of the radial head within the annular ligament against the ulna.

Question 18

What motion occurs at the distal radioulnar joint during supination?

Answer 18

Concave radius moves on convex ulna; roll and glide posteriorly.

Question 19

What motion occurs at the distal radioulnar joint during pronation?

Answer 19

Concave radius moves on convex ulna; roll and glide anteriorly.

Question 20

What arthrokinematics occur at the humeroulnar joint during flexion?

Answer 20

Concave trochlear notch of ulna rolls and glides anteriorly on the convex trochlea.

Question 21

What arthrokinematics occur at the humeroulnar joint during extension?

Answer 21

Concave trochlear notch of ulna rolls and glides posteriorly on the convex trochlea.

Question 22

What arthrokinematics occur at the humeroradial joint during flexion?

Answer 22

Concave radial head rolls and glides anteriorly on the convex capitulum.

Question 23

What arthrokinematics occur at the humeroradial joint during extension?

Answer 23

Concave radial head rolls and glides posteriorly on the convex capitulum.

Question 24

Why are radial head fractures common with falls on an outstretched hand (FOOSH)?

Answer 24

Because the radial head compresses against the capitulum during weight bearing.

Question 25

Describe the motion of the radius and ulna during open-chain pronation and supination.

Answer 25

The radius moves around the stationary ulna.

Question 26

Describe the motion of the radius and ulna during closed-chain pronation and supination.

Answer 26

The humerus and ulna rotate relative to the stationary radius and hand.

Question 27

In closed-chain pronation, how do the humerus and ulna move?

Answer 27

They externally rotate relative to the fixed radius.

Question 28

In closed-chain supination, how are the radius and ulna positioned?

Answer 28

Parallel to each other.

Question 29

What type of arthrokinematics occur at the distal radioulnar joint in closed-chain movements?

Answer 29

Convex ulna moving on concave radius; roll and slide occur in opposite directions.