Truncus arteriosus associated with trisomy 18

Fetal circulation is a unique system that facilitates the exchange of gases, nutrients, and waste products between the developing fetus and the mother. This intricate process takes place through a special organ called the placenta.
Two umbilical arteries transport blood from the fetus to the placenta. At the placenta, the blood absorbs oxygen and nutrients while simultaneously eliminating waste products. This oxygen-enriched and nutrient-rich blood then returns to the fetus through one...

The development of the human heart, a crucial organ, commences from the mesoderm on the 18th or 19th day after fertilization. This process initiates in the cardiogenic area, a group of mesodermal cells at the embryo's head end, which evolves into elongated strands known as cardiogenic cords. These cords undergo a transformation to form hollow-centered endocardial tubes.
As the embryo undergoes lateral folding, these paired tubes approach each other, merging into a single primitive heart tube by...

Once the aorta traverses the diaphragmatic plane at the aortic hiatus, it is known as the abdominal aorta. This anatomical structure is positioned leftward of the spinal column, encased within a cocoon of adipose tissue behind the peritoneal cavity. It terminates at the L4 vertebra, where it splits into the common iliac arteries. Prior to this bifurcation, the abdominal aorta gives rise to several vital branches.
The celiac trunk, a singular artery, divides into the left gastric artery, which...

The thoracic section of the aorta begins at the T5 vertebra and extends to the T12 level at the diaphragm, initially progressing through the mediastinum to the left of the spinal column. Throughout its course in the thoracic segment, the thoracic aorta emits various offshoots known collectively as visceral and parietal branches. The branches that predominantly supply blood to visceral organs are termed visceral branches and include bronchial, pericardial, esophageal, and mediastinal arteries,...

The development of the vascular system in a fetus is a complex and intricate process that begins as early as 15 to 16 days post-conception. This process starts outside the embryo, specifically in the mesoderm of the yolk sac, chorion, and connecting stalk. Approximately two days later, the formation of blood vessels occurs within the embryo itself.
The initial formation of this system is facilitated by the small amount of yolk present in the ovum and yolk sac. Blood vessels originate from...

The azygos system is a crucial part of the body's circulatory system and drains most of the thorax. It comprises the azygos, hemiazygos, and accessory hemiazygos veins.
The azygos vein, positioned just right of the midline and anterior to the vertebral column, begins at the junction of the right ascending lumbar and subcostal veins, terminating in the superior vena cava. This vein drains blood from the right side of the thoracic wall, thoracic viscera, and posterior abdominal wall.
The...