Elbow Joint and Radio-Ulnar Joints Flashcards
What are the three cubital articulations?
humero-ulnar articulation, humero-radial articulation, superior radio-ulnar articulation
What type of joint is the elbow joint?
hinge type of synovial joint
What are the articular surfaces of the humero-ulnar and humero-radial articulations?
Humero-ulnar: trochlea of humerus and trochlear notch of ulna
Humero-radial: capitulum of humerus and upper surface of head of radius
[Diagram]
The distal end of the humerus has three non-articular fossae. Name the three fossae and state their function.
- Coronoid fossa - it lodges the anterior margin of coronoid process of ulna during flexion of the elbow
- Olecranon fossa - it lodges the tip of olecranon process of ulna during extension of the elbow
- Radial fossa - it lodges the anterior margin of the head of radius during flexion of the elbow
- [Diagram]
Describe the attachment of the capsular ligament of the elbow joint.
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]
Describe the attachments of the ulnar collateral ligament (triangular in shape). Also state it’s neurovascular relations.
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]
Describe the attachments of the radial collateral ligament.
fan-shaped band extending from the lateral epicondyle to the annular ligament
[Diagram]
List the bursa related to the the elbow joint.
- Subtendinous olecranon bursa; between triceps tendon and upper surface of the olecranon process
- Subcutaneous olecranon bursa; between skin and subcutaneous triangular area on the posterior surface of the olecranon
- Bicipitoradial bursa, between distal biceps tendon and radial tuberosity
- A small bursa separating the biceps tendon from the oblique cord
State the blood supply to the elbow joint.
By arterial anastomosis around the elbow followed by the branches of brachial, radial and ulnar arteries
Describe the elbow anastomosis.
I recommend you check out this diagram first before reading the answer to make understanding easier: [Diagram]
- 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). - 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). - 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). - 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). - 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.
Describe the nerve supply of the elbow joint.
- Median nerve
- Radial nerve (through its branch to anconeus)
- Ulnar nerve
- Musculocutaneous nerve (through its branch to brachialis)
Name the muscles that bring about flexion (3) and extension (2) of the elbow joint.
Flexion: brachialis, biceps brachii, brachoradialis
Extension: triceps brachii, anconeus
What are the stability factors of the elbow joint? (2)
- Pulley-shaped trochlea of humerus fits properly into the trochlear notch of ulna
- Strong ulnar and radial collateral ligaments
- What is the carrying angle of the elbow joint and what is its normal range?
- What is the anatomical basis of the carrying angle?
- What is the significance of the carrying angle?
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.
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)
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.
