Certified Neuroscience Registered Nurse (CNRN) Practice Exam

What marks the transition point of the esophagus between the thoracic and abdominal cavities?

1. Cardiac sphincter

2. Esophageal hiatus of the diaphragm

3. Pyloric sphincter

4. Duodenum

The correct answer is: Esophageal hiatus of the diaphragm

The correct answer highlights the esophageal hiatus of the diaphragm as the transition point of the esophagus between the thoracic and abdominal cavities. The esophageal hiatus is an opening in the diaphragm through which the esophagus passes as it connects the throat to the stomach. This anatomical structure is crucial as it serves as the boundary separating the thoracic cavity, which contains the lungs and heart, from the abdominal cavity, which houses various digestive organs. Understanding this transition point is important for recognizing the potential complications that can occur in this area, such as hiatal hernias, where part of the stomach can bulge through the hiatus into the thorax. The function of the diaphragm and its continual contraction and relaxation during breathing also play a role in the movement and functionality of the esophagus and its connections to the stomach. In contrast, the cardiac sphincter (or lower esophageal sphincter) functions as a valve that prevents reflux of stomach contents back into the esophagus, but it does not represent the anatomical transition between the two cavities. The pyloric sphincter is located at the outlet of the stomach, regulating the passage of food into the small intestine and is not involved in the transition from thorax to abdomen. The duodenum is the