The esophagus is a continuation of the pharynx and ends at the cardia of the stomach. The transition from pharynx to esophagus is at the lower border at the 6th cervical vertebra which corresponds to the cricoid cartilage anteriorly. The esophagus deviates to the left in the lower portion of the neck, then returns to the midline in the mid-portion of the thorax near the bifurcation of the trachea. In the lower portion of the thorax the esophagus again deviates to the left to pass the diaphragmatic hiatus. Hence, the surgical maneuver of a right thoracotomy for a mid-esophageal lesion, and a left thoracotomy for a lower esophageal lesion. The optimal exposure of the cervical esophagus is in the left neck not only because the esophagus deviates to the left in the neck, but also because the right recurrent laryngeal nerve is further away from the esophagus than the left recurrent laryngeal nerve. Hence, encircling the esophagus with the gloved finger is less likely to include the right recurrent nerve when dissecting from the left neck than it is to include the left recurrent nerve when dissecting from the right neck.
The average distance from the incisors to the cardia of the stomach, i.e. the distance for a complete esophagoscopy, is 40 cm. The esophagus itself is 25 cm long. The cricopharyngeus muscle (i.e. the beginning of the esophagus) is 15 cm from the incisors. The carina is at 25 cm from the incisors and lower esophageal sphincter is 40 cm from the incisors. These three numbers are important for determining anatomic location of tumors on esophagoscopy and their relationship to other intrathoracic structures. This is shown in Figure 17.1.
The fascial relations in the neck are clinically important. These are shown in Figure 17.2. The deep cervical fascia consists of four separate compartments or fascias. The pretracheal fascia surrounds the thyroid, trachea and the esophagus. Superiorly, this attaches to the thyroid and cricoid cartilage. Inferiorly, it extends to the pericardium and laterally blends with the carotid sheath. The investing cervical layer completely surrounds the neck and encloses the sternocleidomastoid and trapezius. Above, it splits to enclose the submandibular gland and parotid, and proceeds then to the base of the skull. The prevertebral fascia encloses the vertebral bodies and prevertebral muscles and extends superiorly to the base of the skull and inferiorly into the thorax. The space between the pharynx and the prevertebral fascia is the retropharyngeal space. It is through this space that infections arising in the deep cervical fascia, for example from dental abscesses, may
DISTANCE FROM INCISORS
DISTANCE FROM INCISORS
Fig 17.1. Endoscopic esophageal distances (measured from incisors).
proceed further inferiorly to develop mediastinal abscesses in the posterior and middle mediastinum, and may even cause pericardial effusion.
Further down in the chest, the esophagus moves to the midline, then to the right. There is a natural narrowing of the esophagus behind the carina. There is another natural narrowing of the esophagus at the cricopharyngeus muscle, and another natural narrowing at the lower esophageal sphincter. It is at these three narrowings where perforations of the esophagus are more likely to occur after instrumentation.
The arterial blood supply of the esophagus is multiple. The upper portion of the esophagus receives blood from the inferior thyroid artery. The mid-portion of the esophagus receives arterial blood from bronchial arteries, and the lower most portion of the esophagus receives blood from the left gastric and inferior phrenic arteries. There is an extensive intramural vascular network in the muscular and submucosal layers, and as a consequence the esophagus can be mobilized from stomach to the aortic arch without fear of devascularization and ischemic necrosis. If the patient had a previous thyroidectomy with ligation of the inferior thyroid arteries proximal to the origin of the esophageal branches, care should be taken in the extent of the esophageal mobilization. This is one reason for taking the inferior thyroid artery close to the thyroid gland during a thyroidectomy.
Venous drainage of the esophagus is via a submucosal venous plexus which enters a peri-esophageal venous plexus. In the cervical region, the veins drain into the inferior thyroid vein; in the thoracic region they drain into the bronchial azy-gous or hemiazygous veins; and in the abdominal region into the coronary (i.e. left gastric) veins.
The esophagus contains squamous epithelium in the upper two-thirds of the esophagus and columnar epithelium in the lower third. There is a submucosal layer and a muscular layer with an inner circular coat and a longitudinal outer coat.
The lymphatic drainage from the cervical esophagus is into the internal jugular nodes and supraclavicular nodes. Drainage may occur into the paratracheal nodes. Drainage from the thoracic portion of the esophagus is into the paraesophageal nodes and paratracheal nodes, as well as inferiorly to the abdominal nodes. This area also drains superiorly into the supraclavicular nodes. The lower thoracic esophagus drains into the para-esophageal and infradiaphragmatic nodes, specifically the left gastric node, celiac nodes and hepatic nodes. There is some evidence that upper esophageal carcinoma is more likely to spread to the infradiaphragmatic nodes than lower esophageal carcinoma is likely to spread to the supraclavicular nodes; i.e. the general trend of esophageal carcinoma is to go inferiorly rather than superiorly. The likelihood of nodal spread of the lower esophagus to go to the intra-abdominal nodes is much higher than the chance of upper esophageal carcinoma going to the supraclavicular nodes.
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Gastroesophageal reflux disease is the medical term for what we know as acid reflux. Acid reflux occurs when the stomach releases its liquid back into the esophagus, causing inflammation and damage to the esophageal lining. The regurgitated acid most often consists of a few compoundsbr acid, bile, and pepsin.