|The Common Vein Copyright 2007
The esophagus is a muscular and tubular organ and is specifically designed for rapid transport of ingested food and water.
As Biological Unit
The esophagus’ distinct structural entity allows for the transport of ingested food and water from the mouth to the stomach. Its distinct structural and functional components are essential for proper function. From its sqaumous mucosa, which acts as a protective layer, to its unique muscular anatomy, each separate biologic unit, comprises this important and interesting organ.
Links and Connections
The esophagus is connected to the posterior oropharynx at its proximal end and to the stomach on the distal side. It has a complex connection with the nervous system with localized nerve plexi as well as connections to the vagus and central nervous system. The vascular system and lymphatic system are also distinctly connected to the esophagus.
Units to Unity
The esophagus itself isn’t needed for life, but the organ provides unity to the intestinal system. It provides continuity such that food can enter one end, be processed, and be excreted, albeit in a different form, out the other. Surgery can remove the esophagus and a person can live, and eat, but the unity of the GI system is interrupted and dietary changes needed.
Dependence and Independence
The esophagus cannot function alone as it requires centrally based innervations and signaling in addition to the receptive relaxation of the muscles to transport food from the oropharynx to the stomach.
However, the esophagus does contain innate sensory neurons that can respond to stimuli, typically distension, that will induce what is referred to as a secondary peristalsis.
Time Growth and Aging
At 4 weeks gestation the esophagus grows from endoderm that also gives rise to the respiratory tract. The dorsal component of this endodermal growth, known as the primitive foregut, ultimately yields the esophagus. The dorsal component of this endodermal growth, known as the primitive foregut, ultimately yields the esophagus. As the esophagus ages, coordination becomes lost tertiary waves become more apparent and uncoordinated contractions progress to an entity called presbyesophagus. The loss of coordination with the oropharynx can result in aspiration and aspiration pneumonia becomes a real threat in the elderly. Aspiration pneumonia is not uncommonly a terminal event in the elderly.
The esophagus traverses three spaces in the body. It starts in the neck, has its major position in the chest and has a small component in the abdomen. It is closely related to the spine, aorta, trachea left main bronchus, the left atrium and the diaphragm. Since it does not have a capsule aggressive esophageal disease easily spreads to neighboring structures in the mediastinum.
Muscular contractions play a key role in the propulsion of a food bolus thru the esophagus. Another key principle that must be remembered is Laplace’s Law which states that the pressure is directly related to the wall tension and inversely related to the radius. The pressure on the wall of the esophagus induces the muscles in the esophagus to contract to help propel the food bolus.
While it may seem simple, the esophagus interacts with the orophayrnx and stomach at a complex level. The control mechanisms that enable the interaction are quite elegant. Failure of the coordinated mechanisms can be disastrous as seen in reflux esophagitis and aspiration.
States of Being Health and Disease
Complaints involving the esophagus are quite common. As discussed if other sections, there are a multitude of disorders that can involve the esophagus. Dysphagia, odynophagia, reflux, chest pain, asthma are just a few of the common manifestations of esophageal disorders.