What is a azygos lobe?
What is a azygos lobe?
An azygos lobe is a rare, anatomical variant of the upper lobe of the right lung found in approximately 1% of anatomic specimens and 0.4% of chest radiographs [1]. Normally, the posterior cardinal vein migrates over the apex of the right lung to its final position in the mediastinum.
How common is azygos lobe?
Epidemiology. An azygos lobe is found in 1% of anatomical specimens 2 and is twice as common in males as females 3.
What does azygos mean in anatomy?
unpaired
Azygos (impar), from the Greek άζυξ, refers to an anatomical structure that is unpaired. This is relatively unusual, as most elements of anatomy reflect bilateral symmetry.
Is azygos lobe rare?
An azygos lobe is a rare normal anatomic variant of the right upper lobe, first described by Heinrich Wrisberg in 1778 [1]. Its prevalence varies from 0.4% on chest radiograph to 1.2% on high resolution CT scans. It is usually diagnosed incidentally on imaging [2].
How azygos lobe is formed?
An azygos lobe forms when the right posterior cardinal vein, one of the precursors of the azygos vein, fails to slide medially over the apex of the lung and instead penetrates it, carrying with it two pleural layers that invaginate into the superior portion of the right upper lobe 2.
What is the purpose 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.
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.
What is Azygos fissure?
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.
Which lung has accessory lobe?
right lung
The present case describes an accessory lobe between middle and lower lobes of right lung. An Azygos lobe of the lung affects the upper lobe of right lung, present in 1% individuals, where Lungs are divided into lobes by oblique and horizontal fissures.
Why azygos vein is called so?
Structure. The azygos vein transports deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava vein. The vein is so named because it has no symmetrically equivalent vein on the left side of the body.
How many azygos veins are there?
Usually, there is a singular azygos vein on the right side of the body. However, the azygos vein is occasionally located in the midline or two independent veins may be present like in early embryonic development.
What causes Azygos fissure?
A convex shaped fissure is created by the course of the vein bearing towards the medial side of the right lung to join with the superior vena cava. Its formation is the result of an unusual embryogenic migration of the posterior cardinal vein, which is a precursor of the vena azygos.
Is the azygos lobe of the lung normal?
In human anatomy, an azygos lobe is a normal anatomical variation of the upper lobe of the right lung. It is seen in 1% of the population.
How does the azygos lobe form in the embryo?
Embryology. An azygos lobe forms when the right posterior cardinal vein, one of the precursors of the azygos vein, fails to migrate over the apex of the lung and penetrates it instead, carrying along two pleural layers that invaginates into the upper portion of the right upper lobe 2.
Where is the azygos vein on the chest?
Azygos lobe on chest x-ray. Arrowheads show the delineation of the lobe. Arrow points to the azygos vein. In human anatomy, an azygos lobe is a normal anatomical variation of the upper lobe of the right lung. It is seen in 1% of the population.
How is the azygos lobe used in computertomography?
However, it can cause technical problems in thoracoscopic procedures. Azygos lobe in axial computertomography. Arrow on azygos vein. HRCT thorax, axial section delineates a well-defined, convex-shaped fold (Blue arrow), the azygos fissure.