Elbow

The elbow refers to the area between the arm and the forearm.

Bony framework:

The bony framework comprises the elbow joint which enables two types of movement:

• Flexion and extension occur when the rounded capitulum of the humerus articulates with the head of the radius and the pulley-like trochlea of the humerus articulates within the U-shaped trochlear notch of the ulna, providing stability to the elbow joint.

• Pronation and supination occur at the superior radioulnar joint. A collar-shaped annular ligament surrounds the head of the radius, connecting to the margins of radial notch of the ulna. The head of the radius pivots on the capitulum, allowing the radial head to rotate freely within the annular ligament, thus enabling the radius to revolve around the ulnar bone, resulting in pronation (palm down) and supination (palm up).

Joint capsule, synovial membrane, bursae, and ligaments:

The stability of the elbow joint is enhanced by:

• The fibrous joint capsule, which merges with the annular ligament and encloses the superior radioulnar joint.

• Medial (ulnar) and lateral (radial) collateral ligaments surrounding the joint capsule.

• A synovial membrane lining the capsule and the annular ligament, enabling smooth movement.

• Extensions of the synovial membrane form membrane-bound synovial sacs called bursae, which surround the joint capsule. The olecranon bursa is clinically significant and may become inflamed due to friction or pressure.

Muscles:

• The biceps brachii and brachialis muscles flex the ventral aspect of the elbow joint.

• The triceps brachii extends the dorsal aspect of the elbow joint.

Cubital fossa:

• The cubital fossa is a shallow triangular depression on anterior surface of the elbow. It is bounded laterally by the brachioradialis muscle and medially by the pronator teres. An imaginary line connecting the medial and lateral epicondyles forms its base.

• The floor is formed by the brachialis and supinator muscles.

• Important anatomical structures (TAN) in this region include the Biceps brachii Tendon, brachial Artery (dividing into ulnar & radial arteries), companion deep veins, and median Nerve.

• The roof is composed of the deep fascia, reinforced by the bicipital aponeurosis, subcutaneous tissue, and skin. The median cubital vein, located within the subcutaneous tissue, connects the cephalic and basilic veins and serves as a significant site for venipuncture.

Vasculature:

• Blood supply to the joint is provided by branches of the brachial, deep brachial (profunda brachii), radial, and ulnar arteries