Elbow Joint and Radio-Ulnar Joints

Question 1

What are the three cubital articulations?

Answer 1

humero-ulnar articulation, humero-radial articulation, superior radio-ulnar articulation

Question 2

What type of joint is the elbow joint?

Answer 2

hinge type of synovial joint

Question 3

What are the articular surfaces of the humero-ulnar and humero-radial articulations?

Answer 3

Humero-ulnar: trochlea of humerus and trochlear notch of ulna
Humero-radial: capitulum of humerus and upper surface of head of radius
[Diagram]

Question 4

The distal end of the humerus has three non-articular fossae. Name the three fossae and state their function.

Answer 4

1. Coronoid fossa - it lodges the anterior margin of coronoid process of ulna during flexion of the elbow
2. Olecranon fossa - it lodges the tip of olecranon process of ulna during extension of the elbow
3. Radial fossa - it lodges the anterior margin of the head of radius during flexion of the elbow
4. [Diagram]

Question 5

Describe the attachment of the capsular ligament of the elbow joint.

Answer 5

a) Superiorly, it is attached to the lower end of the humerus in such a way that the capitulum, the trochlea, the radial fossa, the coronoid fossa and the olecranon fossa are intracapsular.
b) lnferomedially, it is attached to the margin of the trochlear notch
c) Inferolaterally, it is attached to the annular ligament of the superior radioulnar joint.
[Diagram]

Question 6

Describe the attachments of the ulnar collateral ligament (triangular in shape). Also state it’s neurovascular relations.

Answer 6

a) Proximal attachment: medial epicondyle of humerus (anterior band attaches at front of medial epicondyle, posterior attaches at back)
b) Distal attachments: anterior and posterior bands attach at the coronoid (tubercle on medial margin) and olecranon processes of ulna respectively
c) Inferior/oblique band extends between olecranon and coronoid processes

It is crossed by the ulnar nerve.
[Diagram: Ulnar collateral ligament]

Question 7

Describe the attachments of the radial collateral ligament.

Answer 7

fan-shaped band extending from the lateral epicondyle to the annular ligament
[Diagram]

Question 8

List the bursa related to the the elbow joint.

Answer 8

1. Subtendinous olecranon bursa; between triceps tendon and upper surface of the olecranon process
2. Subcutaneous olecranon bursa; between skin and subcutaneous triangular area on the posterior surface of the olecranon
3. Bicipitoradial bursa, between distal biceps tendon and radial tuberosity
4. A small bursa separating the biceps tendon from the oblique cord

Question 9

State the blood supply to the elbow joint.

Answer 9

By arterial anastomosis around the elbow followed by the branches of brachial, radial and ulnar arteries

Question 10

Describe the elbow anastomosis.

Answer 10

I recommend you check out this diagram first before reading the answer to make understanding easier: [Diagram]

1. In front of the medial epicondyle:
   (a) Inferior ulnar collateral artery and branch from the
   superior ulnar collateral artery (branches of the
   brachial artery), anastomose with
   (b) Anterior ulnar recurrent artery (branch of the ulnar
   artery).
2. Behind the medial epicondyle:
   (a) Superior ulnar collateral artery and a branch from the inferior ulnar collateral artery (branches of brachial artery), anastomose with
   (b) Posterior ulnar recurrent artery (branch of the ulnar artery).
3. In front of lateral epicondyle:
   (a) Radial collateral artery (branch of the profunda
   brachii artery), anastomose with
   (b) Radial recurrent artery (branch of the radial artery).
4. Behind the lateral epicondyle:
   (a) Posterior descending artery (branch of the profunda brachii artery), anastomose with
   (b) Interosseous recurrent artery (branch of the posterior interosseous artery); and a branch of common interosseous artery (a branch of the ulnar artery).
5. Above the olecranon fossa:
   (a) Middle collateral artery (branch of the profunda brachii artery), anastomose with
   (b) Transverse branch from the posterior division of the inferior ulnar collateral artery.

Question 11

Describe the nerve supply of the elbow joint.

Answer 11

1. Median nerve
2. Radial nerve (through its branch to anconeus)
3. Ulnar nerve
4. Musculocutaneous nerve (through its branch to brachialis)

Question 12

Name the muscles that bring about flexion (3) and extension (2) of the elbow joint.

Answer 12

Flexion: brachialis, biceps brachii, brachoradialis
Extension: triceps brachii, anconeus

Question 13

What are the stability factors of the elbow joint? (2)

Answer 13

1. Pulley-shaped trochlea of humerus fits properly into the trochlear notch of ulna
2. Strong ulnar and radial collateral ligaments

Question 14

1. What is the carrying angle of the elbow joint and what is its normal range?
2. What is the anatomical basis of the carrying angle?
3. What is the significance of the carrying angle?

Answer 14

1) It is the angle between the axis of the arm and the axis of the forearm. It ranges between 5 and 15 degrees.
2) The medial flange of the trochlea lies about 6 mm below the lateral flange, hence when the elbow is extended, the arm and forearm do not lie in a straight line; the forearm is deviated slightly laterally.
3) This angle permits the forearms to clear the hips in swinging movements during walking and is important when carrying objects.

Question 15

Discuss briefly the following nerve entrapments of the elbow.
a) Median nerve entrapment (2)
b) Ulnar nerve entrapment (2)
c) Posterior interosseous nerve entrapment (2)

Answer 15

a) The median nerve may be compressed where it passes between the two heads of pronator teres or where it passes deep to the fibrous arch between the humero-ulnar and radial heads of flexor digitorum superificialis.
It may also be compressed where it passes deep to Struther’s ligament.
- Compression at carpal tunnel.

b) The ulnar nerve may be compressed where it passes posterior to the medial epicondyle of the humerus (commonest site) or where it passes through cubital tunnel formed by tendinous arch joining the humeral and ulnar heads of flexor carpi ulnaris.
- Compression at Guyon canal

c) The posterior interosseous nerve may be compressed where it passes deep to the arcade of Frohse, a musculoaponeurotic structure at the proximal edge of supinator muscle or where it passes through the substance of supinator muscle.

Question 16

State the following about proximal radio-ulnar joint:
1) type
2) articular surfaces

Answer 16

Type: Synovial joint of pivot variety
Articular surfaces:
- radial head
- radial notch of ulna

Question 17

State the ligaments of the proximal radio-ulnar joint.

Answer 17

1. Joint capsule continuous with that of elbow joint
2. Annular ligament from radial collateral ligament to margins of radial notch of ulna
3. Quadrate ligament extending from neck of radius to the upper part of supinator fossa of ulna just below the radial notch

Further notes:
Functions of the quadrate ligament:
~ it stabilizes the proximal radio-ulnar joint, preventing any unwanted separation or movement between the radius and ulna that isn’t associated with regular forearm rotation
~ it prevents excessive supination [and, to a lesser degree, pronation] [Diagram]

Question 18

State the relations, blood supply, nerve supply and movements of the proximal radio-ulnar joint.

Answer 18

a) Relations:
- Anterolaterally: Supinator
- Posteriorly: Anconeus

b) Blood supply: By articular branches derived from arterial anastomosis on the lateral side of the elbow joint

c) Nerve supply: By articular branches from musculocutaneous, median, radial, and ulnar nerves

d) Movements: supination and pronation

Question 19

Describe the anatomy of the distal radio-ulnar joint under the following subheadings:
1. Type, 2. Articular surfaces, 3. Ligaments, 4. Relations, 5. Blood supply, 6. Nerve supply, 7. Movements

Answer 19

Type: Synovial joint of pivot variety

Articular surfaces:
a) convex head of ulna
b) concave ulnar notch of radius

Ligaments:
- joint capsule
- articular disc; apex attached to the base of styloid process of ulna and its base to the lower margin of the ulnar notch of radius

Relations:
Anteriorly: Flexor digitorum profundus
Posteriorly: Extensor digiti minimi

Blood supply: anterior and posterior interosseous arteries

Nerve supply: anterior and posterior interosseous nerves

Movements: supination and pronation

[Diagram]

Question 20

a) Apart from the interosseous membrane of the forearm, what else holds the radius and ulna together?
b) What is the name of this union?
c) What type of joint is it?

Answer 20

a) oblique cord: from ulnar to radial tuberosities (morphologically representing the atrophied part of FPL muscle)
b) middle radio-ulnar joint
c) syndesmosis type of fibrous joint

Question 21

Discuss Nursemaid’s elbow/pulled elbow. Focus on anatomical basis and how reduction is achieved.

Answer 21

Nursemaid’s elbow occurs most commonly in preschool children (1-3 years old) when the forearm is suddenly pulled in pronation. The head of the radius comes out of the annular ligament [Diagram] and the elbow is kept slightly flexed and pronated. An attempt to supinate the forearm causes severe pain. Reduction is easily achieved by supinating and extending the elbow and simultaneously applying direct pressure posteriorly on the head of radius.

Further notes:
Reduction of Nursemaid’s elbow: [Video]

Question 22

Discuss tennis elbow aka. lateral epicondylitis. Focus on symptoms and causes.

Answer 22

This is a clinical condition characterized by pain and tenderness over the lateral epicondyle of the humerus with aggravated pain during pronation and extension. It commonly occurs due to inflammation of the tendon of extensor carpi radialis brevis at its origin.

Question 23

Discuss golfer’s elbow aka. medial epicondylitis. Focus on symptoms and causes.

Answer 23

It is a clinical condition characterized by pain and tenderness over the medial epicondyle of the humerus with aggravated pain during pronation and flexion. It occurs due to strain or tear of common flexor origin with subsequent inflammation of medial epicondyle, following repetitive use of superficial flexors of forearm as during playing golf.

Question 24

State the myotome:
(a) elbow flexion
(b) elbow extension

Answer 24

(a) C6
(b) C7