The Esophagus- Anatomy
The esophagus is a relatively straight cartilaginous tube, measuring 25-30cm in an adult, which connects to the pharynx and through which food passes into the stomach. It lies behind the trachea and the heart, but in front of the spinal column. Starting at the level of the cricoid cartilage (C6), the esophagus pierces the diaphragm at the vertebral level T10 and enters the stomach at the level T11. There are four constrictions in the oesophagus with the first at its beginning where it connects to the pharynx at the pharyngeo-oesophageal junction. The other constrictions are measured as distances from the incisor teeth, with the second constriction as the oesophagus is crossed by the aortic arch at 9inches from the incisors. At 11inches from the incisor teeth the oesophagus constricts as it is crossed by the left bronchus, and the last constriction, 15 inches from the incisors, is where it passes through the diaphragm. These measurements are carefully adhered to when passing instruments through the oesophagus during surgery. The uppermost constriction is most vulnerable to perforation during oesophagoscopy.
The esophagus can contract and expand to allow food to travel through it and has a peristaltic action, conferred by muscles in the oesophageal wall, which helps push the bolus through the tube. The expansion of the oesophagus upon swallowing food is accommodated by the c-shaped rings of cartilage which form the front of the trachea. These cartilage rings leave a flexible area continuous with the oesophagus that can be collapsed slightly as we hold our breath when swallowing. Problems with the oesophagus can lead to nerve damage and resultant neck pain, numbness, weakness, of paraesthesia. Conversely, nerve compression with these same symptoms of neck pain, and radicular pain, can cause oesophageal dysfunction.
Blood, Nerves, and Sphincters
The oesophagus is supplied with blood by the inferior thyroid artery, the oesophageal branches of the aorta, and the left gastric artery. Venous drainage is through the brachiocephalic vein, the azygos vein, and the left gastric vein from the top of the oesophagus to the lower oesophageal sphincter. Lymphatic drainage occurs through deep cervical nodes in the upper portion of the oesophagus, posterior mediastinal nodes in the middle section, and left gastric nodes in the lower portion. Infection and inflammation of the lymph nodes and glands in the neck can cause neck pain, and impact on oesophageal function.
Innervation of the oesophagus occurs through the recurrent laryngeal nerve in the upper half and by the oesophageal plexus including the vagus nerve in the lower part. Compression of these nerves, or trauma through acute injury or chronic pressure, can cause dysfunction of the esophagus with resultant problems with swallowing, sphincter control, peristalsis, reflux, and muscular spasm and pain. Problems with nerve function are just one of many possible causes of dysfunction in the lower oesophageal sphincter. Excessive alcohol, smoking, use of atropine or beta adrenergic agents, and pregnancy with its correspondingly high progesterone levels can all compromise sphincter control. Excessive weight may also put added pressure on the lower oesophageal sphincter, as can eating excessive amounts of food in one sitting. Factors which help to control oesophageal reflux include the oblique angle of entry of the oesophagus into the stomach, the diaphragm, and the presence of mucosal folds at the lower end of the oesophagus.
At each end of the esophagus is a tight muscular sphincter which can close or open to prevent food passing in and out of the oesophagus. These sphincters also allow for regurgitation, vomiting, and belching. Frequent vomiting, in conditions such as bulimia, can seriously damage the oesophagus, the pharynx, the mouth and the teeth, with both acute and long-term consequences for health. The lower oesophageal sphincter connects the oesophagus to the stomach and if this becomes dysfunctional then it can allow stomach acid and partially digested food to wash back up into the oesophagus, causing heartburn. Stomach acid can be extremely damaging to the oesophagus and may result in precancerous cell-formation, referred to as Barrett’s Oesophagus, if the condition persists.
The common malignant tumor, in the esophagus, is squamous cell carcinoma although rates vary according to geographical region with a high number of cases found in China, Iran, and South Africa. In the west adenocarcinoma is more common, with squamous cell carcinoma actually considered quite rare. The most common benign tumor is leiomyomas. Adenocarcinoma usually arises as a result of Barrett’s Oesophagus in the lower third of the the oesophagus. There is around a 4:1 ration of cases in men compared to women, with people tending to be in the 65-75yr age range.
Repeated minor trauma, such as swallowing hot liquids, can increase the risk of oesophageal cancer as can opium use, smoking, alcohol, achalasia, irradiation treatment, and the presence of tylosis (a condition of hyperkeratosis in the palms or soles which also affects the oesophagus in around 45% of cases). Hiatus hernia, reflex oesophagitis, and oesophageal diverticulum all also contribute to an increased risk of cancer.
Symptoms and features of oesophageal cancer include progressive, painless, dysphagia (swallowing disorder), first with solid foods then with liquids. Patients may also experience pain after eating, loss of appetite, weight loss, and possible hoarseness if the recurrent laryngeal nerve has been affected. Perforation and localised sepsis may happen which can cause tracheo-oesophageal fistula. Problems with breathing due to the proximity of the oesophagus to the trachea, can occur with coughing and bronchopneumonia possible. Anaemia, due to blood loss and malnutrition may also be present. Patients will usually undergo and endoscopy with blood work and possible biopsy to check for carcinoma. A barium test may reveal irregular constriction, inflation, or perforation in the oesophagus.
What it could be if its not cancer
A differential diagnosis for oesophageal cancer may be acute pharyngitis, retro-pharyngeal abscess, enlarged cervical glands, thyroid problems, tonsillitis, diphtheria, problematic foreign body lodged in the oesophagus, gastro-oesophageal reflux disease (GORD/GERD), and achalasia, amongst others. Oesophagectomy, or surgical resection of the oesophagus, remains one of the most complicated elective surgical procedures, with the highest mortality rate of any elective surgery (Lamb and Griffin, 2005). Ulceration of the oesophagus, and bleeding, can also occur through acid damage from gastric juices. Destruction of the nerve endings in the oesophagus, from acid damage, and other conditions, can cause achalasia which is an inability to swallow or to pass food into the stomach from the oesophagus. Scleroderma, a disease of collagenous tissue can affect oesophageal function, and muscular spasm can also cause problems with swallowing and acid reflux. Pain in the neck and chest may occur with some of these conditions, and the potential for nerve damage, or for damaged nerves to cause these conditions, makes other cervical symptoms likely. Brachial plexus damage, thoracic outlet syndrome, problems with the thyroid glands, or cervical lymph nodes, can all be connected to oesophageal dysfunction in the role of cause or effect.
Lamb, P., Griffin, S., (2005), The Anatomy and Physiology of the Oesophagus, Upper Gastrointestinal Surgery, Springer Specialist Surgery Series, 2005, 1-15.