Session 8: Functional Anatomy of the Elbow and Forearm

Question 1

How many articulations does the elbow joint consist of and which?

Answer 1

Two.
Humeroulnar joint
Humeroradial joint

Question 2

Which parts articulate in the humeroulnar joint?

Answer 2

Between the trochlea of the humerus and the trochlear notch (also called sigmoid notch) of the ulna.

Question 3

Which parts articulate in the humeroradial joint?

Answer 3

Between the capitellum and the radial head.

Question 4

There is a joint close to the elbow joint which is not a part of it. Which? Which articulations?

Answer 4

Proximal radio-ulnar joint between the head of the radius and the radial notch of the ulna.

Question 5

What are the two condyles of the distal humerus?

Answer 5

Trochlea articulating with the ulna and the capitellum articulating with the radial head.

Question 6

What is located just above the condyles?

Answer 6

The epicondyles.

Question 7

What’s the major role of the epicondyles? (each epicondyle)

Answer 7

The medial epicondyle provides attachment for the flexor-pronator group of muscles in the anterior forearm.

The lateral epicondyle provides attachment for the extension group in the posterior forearm.

Question 8

During flexion and extension of the elbow certain parts of the elbow joint are accommodated into fossae of the humerus. Which?

Answer 8

During flexion the radial head is held in the radial fossa of the humerus. During flexion the coronoid process is held in the coronoid fossa.

During extension the olecranon is held in the olecranon fossa.

Question 9

Where does the biceps tendon insert?

Answer 9

Into the radial tuberosity distal to the radial head and neck.

Question 10

Where does the triceps brachii insert?

Answer 10

Onto the olecranon of the ulna.

Question 11

What ligaments strengthen the elbow joint?

Answer 11

The radial (lateral) collateral ligament
The ulnar (medial) collateral ligament

Question 12

Describe the radial collateral ligament.

Attachment and role.

Answer 12

Fan shaped structure which attaches between the lateral epicondyle of the humerus and annular ligament of the radius for which it blends with.

Keeps the head of the radius and the capitellum in close association during pronation and supination of the forearm.

Question 13

Describe the ulnar collateral ligament.

Attachment and role.

Answer 13

Triangular ligament.
Between the medial epicondyle of the humerus and the coronoid process and olecranon of the ulna.

It consists of three bands in total:
Anterior (strongest)
Posterior (weak)
Inferior (deepens the sockets for the trochlea of the humerus)

Question 14

What ligament strengthens the proximal radioulnar joint?

Attachment and role.

Answer 14

The annular ligament.
It attaches only on the radial head. It forms a collar around the radial head within which the radial head can rotate whilst maintaining its contact with the radial notch of the ulna.

This provides for safe supination and pronation of the forearm.

Question 15

Movements of the elbow joint.

Answer 15

Flexion and extension.

Question 16

What angle does the ulna make with the long axis of the humerus at full extension of the elbow joint?
What is another term for this angle? Why is it important?

Answer 16

The valgus angle (lateral angle)
Also called the carrying angle and is around 5-10 degrees in men and 10-15 degrees in women.
Permits the forearm to clear the hips swinging movements of the arm during walking.

Question 17

What is an excessive carrying angle called?

What is a too small carrying angle called?

Answer 17

Excessive => cubitus valgus (away from the body)

Too small => cubitus varus

Question 18

Major muscles that flex the elbow.

Minor muscles that flex the elbow.

Answer 18

Major:
Brachialis
Biceps Brachii
Brachoradialis

Minor:
Muscles originating from the common flexor origin on the medial humeral epicondyle

Question 19

Major extensors of the elbow joint.

Minor extensors of the elbow joint.

Answer 19

Major:
Triceps brachii

Minor:
Anconeus
+
Muscles originating from the common extensor origin on the lateral humeral epicondyle.

Question 20

Movements of the proximal and distal radioulnar joints.

Answer 20

Pronation and supination.

Question 21

Muscles the pronate the forearm.

Answer 21

Pronator quadratus

Pronator teres

Question 22

Muscles the supinate the forearm.

Answer 22

Supinator (during no resistance)
Biceps brachii (during resistance)

Question 23

Two important bursae of the elbow:

Answer 23

Olecranon bursa

Subtendinous bursa

Question 24

Location of the olecranon bursa.

Answer 24

Lies in subcutaneous connective tissue overlying the olecranon

Question 25

Location of the subtendinous bursa.

Answer 25

Lies between the triceps tendon and the tip of the olecranon.

Question 26

Role of the bursae.

Answer 26

Reduce friction between the bone and skin/subcutaneous tissue (olecranon bursa) or between tendon and bone (subtendinous bursa).

Question 27

Location, articulations and role of the distal radio-ulnar joint.

Answer 27

Located immediately proximal to the wrist.
Pivot joint.
Ulnar notch of the radius rotates anteriorly around the head of the ulna to permit supination and pronation.

Question 28

What separates the distal radioulnar joint from the wrist joint? What other role does this structure have?

Answer 28

A fibrocartilaginous disc called the triangular fibrocartilage complex which binds the radius and ulnar together.

Question 29

There is another fibrous joint between the radius and ulna. Which?

Answer 29

The interosseous membrane.

Its fibres run diagonally from the radius proximally to the ulna more distally.

Question 30

Role of the interosseous membrane.

Answer 30

Keeps bones together during the movements of pronation and supination.
Prevents proximal displacement of the radius as force is applied to the outstretched hand.