What does azygos lobe mean?

An azygos lobe is formed during embryological development when the right posterior cardinal vein aberrantly migrates through the upper lobe of the right lung rather than over the apex. As a result, two pleural layers are carried through the right upper lobe creating a fissure known as the azygos fissure (See Figure 1).

What causes an azygos lobe?

The azygos lobe is formed when the right posterior cardinal vein, which is one of the precursors of the azygos vein penetrates the right lung apex, rather than migrating over it. The cardinal vein carries both pleural layers with it, resulting in entrapment of a portion of the right upper lobe.

Where is the azygos lobe?

right lung
The azygos lobe, also commonly referred to as an accessory lobe of the azygos vein, is located at the apicomedial portion of the right lung and is separated from the remainder of the upper lobe by a fissure. It usually has no significant clinical implications and is an incidental finding in radiographic studies.

Does everyone have an azygos lobe?

In human anatomy, an azygos lobe is a normal anatomical variation of the upper lobe of the right lung. It is seen in 0.3% of the population.

Is azygos lobe genetic?

The azygos lobe may be located behind the superior vena cava and trachea, and may be in proximity of the descending aorta and medial wall of the esophagus. [6] It is more common in males and has genetic predisposition.

Is Azygos fissure normal?

The azygos vein, located at the bottom of the fissure, is visible as a teardrop-shaped opacity [2]. The incidence of this normal variant is estimated between 0.4% and 1.2% [2; 4]. Accessory pulmonary fissures, including the azygos fissure, are known to affect up to 50% of the population.

Is azygos lobe hereditary?

The azygos lobe is more common in males,5 and a familial incidence has been reported.

What is the function of the azygos vein?

It is responsible for draining the thoracic wall and upper lumbar region via the lumbar veins and posterior intercostal veins 1. It also provides important collateral circulation between the superior and inferior venae cavae should they become obstructed 2.

Which veins are part of the Azygous system?

This system consists of the azygos vein and its two main tributaries: the hemiazygos vein and the accessory hemiazygos vein. The azygos vein usually arises either from the lumbar azygos vein or from the posterior side of inferior vena cava around the level of renal veins.

What does Azygos fissure mean?

azygos fissure is a developmental abnormality caused by the right posterior cardinal vein (one of the precursors of the azygos vein) failing to migrate over the right lung apex, and instead penetrating and grooving it.

Where does the azygos vein drain into?

superior vena cava
The azygos vein usually originates from the posterior aspect of the inferior vena cava, at the level of the renal veins. It ascends within the posterior mediastinum to the level of T4 before it arches above the right pulmonary hilum. It drains into the superior vena cava just before it pierces the pericardium.

What is an extra lobe on the lung?

An azygos lobe is an accessory lobe of the lung that may occasionally be confused with a pathological process such as a bulla, lung abscess or neoplasm.