Elbow joint: Ligaments, Relations, Bursae, Applied anatomy

What is the elbow joint?

Elbow joint is a hinge type of synovial joint and present between the lower end of the humerus bone and upper ends of the radius and ulnar bone. It literally includes two articulations:

1. Humero-ulnar articulation:
   • It is present between the trochlea of the humerus bone and the trochlear notch of the ulna bone.
2. Humero-radial articulation:
   • It is present between the capitulum of the humerus bone and the head of the radius bone.

On the surface, the elbow joint which a line of the elbow situated about 2 cm below the line joining the two epicondyles of the humerus bone. The complexity of this elbow joint is furthermore increased by its continuity with the superior (upper) radio-ulnar joint. There are three articulations present in the elbow region, viz.

1. Humero -ulnar
2. Humero-radial, and
3. Superior (proximal) radio-ulnar.

The elbow joint is also known as cubital articulations.

Articular surfaces

• Upper articular surface: It formed by the capitulum and the trochlea of the lower extremity of the humerus bone.

• Lower articular surface: It formed by the superior surface of the head of the radius bone and the trochlear notch of the ulna.

1. Capitulum:
   • It is a rounded hemispherical eminence that possesses a smooth articular surface area only on its anterior and inferior aspects.
2. Trochlea:
   • It is medial to the capitulum in the bone & bears a resemblance to a pulley. The medial flange of the trochlea which is projects to an inferior (lower) level than its lateral flange.
3. The trochlear notch of the ulna:
   • It is composed of the upper surface of the coronoid process and the anterior surface of the olecranon process the ulna.
4. The upper end of radius:
   • It is circular in outline present and slightly depressed area in the center.

Ligaments

• Capsular ligament (Joint capsule).
• Medial ligament (Ulnar collateral ligament).
• Lateral ligament (Radial collateral ligament).

Relations

Anterior:

• Brachialis muscle.
• Median nerve.
• Brachial artery.
• Tendon of biceps brachii.

Posterior:

• Tendon of the triceps muscle
• Anconeus muscle

Medially:

• Flexor carpi ulnaris
• Ulnar nerve (posteromedially)
• Common flexor origin of the muscles of the forearm in anteromedially.

Laterally (posterolateral):

• Supinator
• Common extensor origin of muscles of the forearm
• Extensor carpi radialis brevis muscle

Bursae related to the elbow joint

• Four important bursae are present in this joint, they are following;

1. 1. The subtendinous olecranon bursa:
      • It is a small bursa present between the triceps tendon and the upper surface of the olecranon process of the ulnar bone.
   2. The subcutaneous olecranon bursa:
      • It is a large bursa present between the skin area and subcutaneous triangular area on the posterior surface of the olecranon.
   3. Bicipitoradial bursa:
      • It is a small bursa separating the biceps tendon from the smooth or plane anterior part of the radial tuberosity.
   4. A small bursa that separating or dividing the biceps tendon from the oblique cord.

Stability of the elbow joint

• The pulley-shaped trochlea of the humerus fits correctly into the jaw-like trochlear notch of the ulnar bone.
• Strong ulnar ligament and radial collateral ligament

Arterial supply

It is supplied by arterial anastomosis around the elbow joint is formed by the branches of the brachial artery, radial, & ulnar arteries.

Nerve supply

By articular branches from:

• Radial nerve (through its branch to anconeus),

• Musculocutaneous nerve (through its branch to brachialis),

• The ulnar nerve, and

• Median nerve.

Movements of the elbow joint

• Flexion: (muscle)

• • Brachialis
  • Biceps brachii
  • Brachioradialis

• Extension: (muscle)
  • Triceps
  • Anconeus

Applied anatomy

• Elbow effusion.

• Dislocation of the elbow joint.

• Nursemaid’s elbow/pulled elbow (subluxation of the head of the radius bone).

• Tennis elbow (lateral epicondylitis).

• Golfer’s elbow (medial epicondylitis).

• Student’s elbow (Miner’s elbow).

• Nerve entrapments (compressions) around the elbow joint.

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