Anatomy for Diagnostic Imaging. CT of the esophagus: spectrum of disease with emphasis on esophageal carcinoma. Thieme Atlas of Anatomy. Inderbir Singh.
Textbook of Anatomy with Colour Atlas. Michael P. Federle, R. Brooke Jeffrey, Paula J. Diagnostic Imaging. Related articles: Anatomy: Abdominopelvic. Promoted articles advertising. Esophageal landmarks: annotated Esophageal landmarks: annotated. The ventral fasciculus is attached to the vertical ridge on the posterior surface of the lamina of the cricoid cartilage by the tendocricoesophageus. The two lateral fasciculi are continuous with the muscular fibers of the pharynx.
The longitudinal fibers descend in the esophagus and combine to form a uniform layer that covers the outer surface of the esophagus. The circular muscle layer provides the sequential peristaltic contraction that propels food toward the stomach. The circular fibers are continuous with the inferior constrictor muscle of the hypopharynx; they run transverse at the cranial and caudal regions of the esophagus, but oblique in the body of the esophagus.
The internal muscular layer is thicker than the external muscular layer. Below the diaphragm, the internal circular muscle layer thickens and the fibers become semicircular and interconnected, constituting the intrinsic component of the LES. Accessory bands of muscle connect the esophagus and the left pleura to the root of the left bronchus and the posterior of the pericardium.
The muscular fibers in the cranial part of the esophagus are red and consist chiefly of striated muscle; the intermediate part is mixed; and the lower part, with rare exceptions, contains only smooth muscle. The upper esophageal sphincter UES is a high-pressure zone situated between the pharynx and the cervical esophagus Figure 7. The UES is a musculocartilaginous structure composed of the posterior surface of the thyroid and cricoid cartilage, the hyoid bone, and three muscles: cricopharyngeus, thyropharyngeus, and cranial cervical esophagus.
Each muscle plays a different role in UES function. The thyropharyngeus muscle is obliquely oriented, whereas the cricopharyngeus muscle is transversely oriented. Between these two muscles, there is a zone of sparse musculature—the Killian's triangle, from which Zenker's diverticulum might emerge. The cricopharyngeus CP muscle is a striated muscle attached to the cricoid cartilage.
It forms a C-shaped muscular band that produces maximum tension in the anteroposterior direction and less tension in lateral direction.
It is composed of a mixture of fast- and slow-twitch fibers, with the slow fibers being predominant and having a diameter of 25 to 35 m. The CP is suspended between the cricoid processes, surrounds the narrowest part of pharynx, and extends caudally where it blends with the circular muscle of the cervical esophagus.
The cervical esophagus contains predominantly striated muscle fibers, but occasionally smooth fibers are found in the center of the muscle.
The external longitudinal layer of the cervical esophagus originates from the dorsal plane of the cricoid cartilage constituting a sparse muscle area: the Laimer's triangle. The external longitudinal layer courses down the length of the entire esophagus. At its distal end the longitudinal fibers become more oblique and end along the anterior and posterior gastric wall. Upper esophageal sphincter function is controlled by a variety of reflexes that involve afferent inputs to the motor neurons innervating the sphincter.
These reflexes elicit either contraction or relaxation of the tonic activity of the UES. Inability of the sphincter to open or discoordination of timing between the opening of the UES with the pharyngeal push of ingested contents leads to difficulty in swallowing known as oropharyngeal dysphagia.
The lower esophageal sphincter is a high-pressure zone located where the esophagus merges with the stomach Figure 8. The LES is a functional unit composed of an intrinsic and an extrinsic component. The intrinsic structure of LES consists of esophageal muscle fibers and is under neurohormonal influence. The extrinsic component consists of the diaphragm muscle, which functions as an adjunctive external sphincter that raises the pressure in the terminal esophagus related to the movements of respiration.
Figure 9. Malfunction in any of these two components is the cause of gastroesophageal reflux and its subsequent symptoms and mucosal changes. The esophageal opening is created by a loop of right crux of the diaphragm. The intrinsic component of the LES is composed of circular layers of the esophagus, clasp-like semicircular smooth muscle fibers on the right side, and sling-like oblique gastric muscle fibers on the left side.
The clasp-like semicircular fibers have significant myogenic tone but are not very responsive to cholinergic stimulation, whereas the sling-like oblique gastric fibers have little resting tone but contract vigorously to cholinergic stimulation. The extrinsic component of the LES is composed of the crural diaphragm, which forms the esophageal hiatus, and represents a channel through which the esophagus enters into the abdomen. The crural diaphragm encircles the proximal 2 to 4 cm of the LES , and determines inspiratory spike-like increases in LES pressure as measured by esophageal manometry.
The endoscopic localization of the LES is different from the manometric localization. The endoscopic localization of the LES is presumably determined by changes in the esophageal mucosa color owing to transition from nonstratified squamous esophageal epithelium to the gastric mucosa, changes known as the Z-line.
Three-dimensional 3D manometric measures of the lower esophageal high-pressure zone showed a marked radial and longitudinal asymmetry, with higher pressures toward the left posterior direction. Radial pressures peak at the respiratory inversion point during esophageal manometry where inspiration converts from a positive pressure as measured by pressure sensors to a negative pressure as the pressure sensor enters the intrathoracic cavity.
The high-pressure zone appears to coincide with asymmetric thickening of the muscular layer at the gastroesophageal junction, which corresponds to the gastric "sling" fibers and to the semicircular "clasp" fibers. The LES is innervated by both parasympathetic vagus and sympathetic primarily splanchnic nerves, with the vagal pathways being essential for reflex relaxation of LES.
The motor innervation of the LES is topographically provided through preganglionic fibers from the dorsal motor nucleus of the vagus. The dorsal motor nucleus and the tractus solitarius nucleus form a dorsal vagal complex in the hindbrain that coordinates reflex control of the sphincter. The wall of the esophagus consists of four layers: mucosa, submucosa, muscularis propria, and adventitia.
Unlike other areas of the GI tract, the esophagus does not have a distinct serosal covering. This allows esophageal tumors to spread more easily and makes them harder to treat surgically. The mucosa is thick and reddish cranially and more pale caudally. It is arranged in longitudinal folds that disappear upon distention. It consists of three sublayers:. The submucosa contains connective tissue as well as lymphocytes, plasma cells, nerve cells Meissner's plexus , vascular network Heller plexus , and mucous glands.
The esophageal glands are small racemose glands which have acini arranged like grapes on a stem of mucous type. Their secretion is important in esophageal clearance and tissue resistance to acid. The muscularis propria is responsible for motor function. In between there is a mixture of both, called the transition zone. Functionally the transition zone can be observed with manometry as a region where there is no significant contraction amplitude during a peristaltic contraction that travels down the body of the esophagus.
The adventitia is an external fibrous layer that covers the esophagus, connecting it with neighboring structures. It is composed of loose connective tissue and contains small vessels, lymphatic channels, and nerve fibers. Tracheoesophageal fistula and esophageal atresia are the most frequent congenital esophageal abnormalities.
Tracheoesophageal fistula results from defects in the separation of the respiratory tract from the foregut. Esophageal atresia results from failure of the primitive gut to recanalize during week 8.
Five types of congenital esophageal atresia with or without tracheoesophageal fistula have been recognized 32 : Figure The figure shows both tracheoesophageal fistula A-E and tracheal abnormalities F-J. Note that A-E do not correspond with the classification of the type of tracheoesophageal fistula. The most common variant is type C, with an incidence of It presents as a blind esophageal pouch with a fistula between the trachea and the distal esophagus.
The fistula often enters the trachea close to the carina. The second most common anomaly is type A, pure esophageal atresia without tracheoesophageal fistula. Esophageal atresia with tracheoesophageal fistula occurs in one in to one in births. When studies over the last 30 years had been conducted, there were no changes in the incidence of tracheoesophageal fistula and esophageal atresia, but decrease in the subsequent mortality had been found.
Clinically, esophageal atresia should be suspected when polyhydramnios is present in the mother. Polyhydramnios develops as a consequence of the inability of the fetus to swallow and thus absorb amniotic fluid. On physical examination of the newborn, a scaphoid abdomen and the regurgitation of saliva are indicators of GI obstruction.
If rapid onset of choking, coughing, and regurgitation are present at the first feeding, suspicion of esophageal atresia is raised. When esophageal atresia is suspected, a nasogastric tube insertion should be attempted.
If atresia is present, an inserted nasogastric tube will typically stop at 10 to 12 cm. The atretic upper esophagus ends in a blind pouch, and the trachea communicates with the distal esophagus. Air enters the GI tract via the tracheoesophageal fistula and the newborn presents clinically with a gas-filled abdomen and frequent aspiration pneumonias due to gastric reflux into the respiratory tract through the fistula.
Confirmation of the type of esophageal atresia is obtained by esophagography with or without bronchoscopy. Treatment of esophageal atresia and tracheoesophageal fistula is surgical, and the procedure depends on the type of esophageal atresia and the distance between the two esophageal segments. Thus, if the distance between the esophageal segments is short, end-to-end anastomosis is the preferred surgical procedure.
If the distance between segments is long, lengthening of the upper esophageal segments in some cases can be achieved using bougienage or intraoperative myotomy. The results of surgical correction are generally excellent when the esophageal malformation is an isolated anomaly.
Overall outcome is determined by the associated genetic malformation, age of infant, and birth weight. Long-term outcome after esophageal atresia repair indicates that the most significant problems are GI and respiratory symptoms.
Gastroesophageal reflux disease symptoms may be alleviated by pharmacologic treatment or with time, owing to the patient's accommodation with the medical condition, but there is a higher risk of developing chronic esophagitis and Barrett's metaplasia compared to the normal population. The aesthetic aspects of the surgical treatment are now becoming more important in adults with esophageal atresia owing to good functional results of applied treatments.
Congenital esophageal stenosis represents narrowing of the esophageal lumen. It can be located at any level of the esophagus, but is more frequent in the distal third. It appears either as a web membranous diaphragm or a long segment of esophagus with a threadlike lumen fibromuscular stenosis.
Usually, the esophageal stenosis results from incomplete esophageal recanalization during the eighth week of human embryologic development, but it also may result from failure of esophageal blood vessels to develop in the affected area. The incidence of esophageal stenosis is low, occurring in 1 in every 25, live births. Patients may present with aspiration and recurrent pneumonia in early infancy. Dysphagia and regurgitation of solid food are symptoms that appear later in childhood, when more solid foods are added to the child's diet.
If the esophageal stenosis is not severe, its diagnosis may be postponed until adulthood, when a history of long-standing solid foods dysphagia could be documented. Once suspicion of congenital esophageal stenosis is raised, an upper endoscopy with biopsy and pH monitoring of the esophagus help with diagnosis and eliminate the possibility of a stricture secondary to gastroesophageal reflux.
Barium swallow typically demonstrates narrowing of the esophagus lumen. The first approach to treatment is with dilation, which may include bougienage or pneumatic dilation under fluoroscopic guidance.
Dilation may be diagnostic and therapeutic. Although pneumatic dilation expands and stretches a fibromuscular stenosis, a persistent "waist" in the balloon may indicate a cartilaginous ring and the necessity for surgical resection.
The efficacy of dilatation seems to be limited and may even result in severe complications such as chest pain, mucosal tears, or esophageal rupture. When pneumatic dilation fails, surgical treatment may be required for removal of the abnormal segment. Laser lyses of webs or stenosis stenting have been described and may be attempted in selected cases. When respiratory tissue is present on esophageal stenosis biopsy, surgical removal of the involved segment is necessary owing to high risk of malignant transformation.
Foregut duplications include esophageal cysts tubular duplications and bronchogenic cysts. They originate from failure of the primitive foregut to become completely vacuolated during the embryonic life. These cyst- or tube-like structures develop independently and rarely are in continuity with the esophagus.
They can be associated with other congenital malformations, such as tracheoesophageal fistulas, spinal abnormalities, esophageal atresia distal to duplication, and other segmental GI duplications small bowel is more frequent. Duplications of the GI tract have three common characteristics:. The congenital duplication cysts represent 0. They are lined by squamous columnar, cuboid, or ciliated epithelium, surrounded by two layers of smooth muscle.
Usually they are accidentally discovered on chest computed tomography CT scans and are asymptomatic. Cysts may become symptomatic owing to complications such as respiratory system compression causing stridor, cough, or tachypnea , digestive system compression causing chest pain or dysphagia , cardiac compression causing cardiac arrhythmias , infarction, rupture, or, rarely, neoplastic dysplasia.
Congenital esophageal duplications may be separated from the esophagus or may share a common wall. Duplications may also contain gastric mucosa.
Duplications of the esophagus can be associated with vertebral anomalies and intraspinal cysts and often are associated with intraabdominal intestinal duplications. A chest x-ray may demonstrate a soft tissue mass with a mediastinal shift. Barium swallow can detect tubular esophageal duplication, but miss the esophageal cyst that does not communicate with the esophageal lumen. A CT scan delineates anatomy of the mass prior to surgical resection, and a nuclear technetium scan may help identify ectopic gastric mucosa.
Definitive treatment involves complete surgical resection of the duplication, even for asymptomatic cysts. The congenital esophageal ring is a concentric extension of the normal esophageal tissue, usually consisting of different anatomic layers including mucosa, submucosa, and sometimes muscles. The location is variable, but most are found in the distal esophagus. There are three types of esophageal rings: types A, B. Esophageal rings may originate from incomplete vacuolization of the esophageal columnar epithelium during early embryonic life; however, they are also associated with immunologic 63 or inflammatory conditions such as scleroderma, chronic graft-versus-host disease , 64, 65 and gastroesophageal reflux.
The type A esophageal ring is a muscular ring located roughly 2 cm proximal to the squamocolumnar junction and it represents a proliferation of the proximal border of the LES. At beginning, it is located between vertebral column and trachea, slightly left of midline and 5 cm left of vertebral column at level of diaphragmatic hiatus Figure 4. Parietal sheet of pleura is tightly connected to both sides of vertebral column, and these connections cause esophageal-pleural recesses that make dissection of esophagus in thorax more difficult.
Thus, if a pleural rupture occurs in this area during surgery, fixing rupture can present a challenge for surgeon [ 2 ]. Arteries of Esophagus. As previously discussed, esophagus within thoracic cavity contains three classical narrowings, two conditional narrowings, and two curves.
Most important and challenging structure in this region is thoracic duct, which lies behind esophagus throughout thorax. Thoracic duct is located slightly apart from esophagus in inferior third part of thorax, but it comes closer as esophagus goes upward. Trachea, aortic arch, right pulmonary artery, left main bronchus, plexus of esophagus, pericardium, left atrium, and anterior vagus nerve are found anterior to esophagus.
At posterior side, esophagus connects to vertebral column, longus colli muscle, posterior intercostal arteries, azygos vein, hemiazygos vein, anterior wall of aorta, posterior vagal nerve, and pleura. Aortic arch, left subclavian artery, left inferior laryngeal nerve, left vagus nerve, thoracic ductus, and thoracic part of aorta are located on left side of esophagus. Azygos vein, pleura of mediastinum, right main bronchus, and right vagus nerve are located on right side. Close proximity of upper two-thirds of esophagus to thoracic duct increases risk of thoracic duct injury in middle and upper mediastinal dissection of esophagus; thus, careful dissection should be performed in this area.
The area between aortic arch and esophagus is comprised of aorticoesophagial muscle fibers that include large vessels; dissection of this area is fairly simple, except in the case of tumor invasion. If tumoral invasion occurs among these large vessels, removal is challenging and dangerous.
Upper mediastinum becomes narrower above aortic arch, and esophageal tumors can easily infiltrate left recurrent laryngeal nerve and respiratory system; however, aortic arch and azygos vein block tumors in these areas to infiltrate lower parts of mediastinum.
Lower parts of thoracic esophagus are surrounded by soft areolar tissue. Here esophagus is not touching adjacent organs and descends slightly away from the vertebral column, making dissection and resection easier and tumor infiltration more difficult in this area. Two weak areas in esophagus that can be vulnerable to pulsing diverticula are upper and lower parts of a cricoid muscle.
In addition, another weak area is located on left posterior esophageal wall, very close to diaphragmatic hiatus, spontaneous rupture of esophagus can occur [ 2 , 10 ]. Abdominal esophagus is 1—2. The plane passes through 7th rib cartilage and sternum anteriorly. It passes through esophageal hiatus of diaphragm, which is comprised of muscular fibers of right crus. The anterior side is longer than posterior side of esophagus because diaphragmatic crura are oblique.
Anterior and lateral sides are partially covered by visceral peritoneum, and posterior side is nonperitoneal side. Three ligaments connect esophagus to spleen, liver, and diaphragm. They are hepatogastric ligament, gastrosplenic ligament, and gastrophrenic ligament.
Following structures are located near abdominal esophagus: posterior side segment of two-thirds of liver, left vagus nerve and esophageal plexus anteriorly, left and right crus of diaphragm, aorta and left inferior phrenic artery posteriorly, caudate lobe of liver at the right side, and fundus of stomach at left side.
Esophageal hiatus is located on right side of midline and is 2 cm in diameter. Topographically, it is located at 10th vertebral plane. Phrenoeosophagial ligament is primary part of antireflux mechanism that includes Gubaroff valvula and angle of Hiss Figure 5.
This ligament consists of subpleural fascia, pleura, phrenoesophageal fascia, and transverse fascia of abdomen and peritoneum. This ligament makes gastroesophageal junction both flexible and tight [ 12 , 13 ].
Veins of Esophagus. However, under hiatus, membrane is loose and long. Phrenogastric ligament lies between diaphragm and cardia of stomach and both vagus nerves. Vagus nerves hang esophagus to thoracic cavity; thus, cutting vagus nerves elongates esophagus 4—5 cm [ 2 ]. Inferior thyroid artery provides primary arterial flow to the cervical esophagus, and subclavian artery, main carotid artery, vertebral arteries, ascendant pharyngeal artery, superficial cervical artery, and costocervical trunk are other arterial blood flow providers to cervical esophagus.
Thoracic portion of esophagus takes blood flow from aorta, bronchial arteries, and right intercostal arteries. The abdominal esophagus is fed by left gastric artery, short gastric arteries, and descending branch of left phrenic artery.
Inferior thyroid artery supplies arterial blood flow to cervical portion of esophagus Figure 6. An excessively low resection of cervical esophagus causes devascularization to this area. In addition, aggressive resection and mobilization or laceration of bronchial artery, or cutting recurrent branches of left gastric artery and inferior phrenic artery causes devascularization at level of tracheal carina. Esophageal arterial blood flow is extremely rich and adequate for anastomosis, but a poor blood supply or careless or over aggressive dissection can cause anastomotic leakage in esophagus [ 14 — 16 ].
Relation among esophagus, diaphragm, and aorta with permission from Turkish Surgery Association. Venous system of esophagus begins at submucosal plexus, which perforates muscular layer and empties into azygos system. Cervical portions of venous drainage empty into inferior thyroid veins. The distance from the incisor teeth to the cricopharyngeus is 15 cm in men and 14 cm women. The bifurcation of the trachea and the indentation of the aortic arch range between 24 and 26 cm from the incisor teeth.
When esophageal surgery is being planned, it is helpful to locate intraluminal tumors, strictures, or other pathology in reference to this landmark to help guide a decision regarding a right or left thoracotomy approach and avoid interference with the aortic arch. Figure A: Topographic relationships of the cervical esophagus: a hyoid bone, b thyroid cartilage, c cricoid cartilage, d thyroid gland, e sternonclavicular joint, f C6.
B: Lateral radiographic appearance. Barium esophagogram. A: Anteroposterior view. B: Lateral view. Important clinical endoscopic measurements of the esophagus in adults.
Esophageal length may be determined by manometric assessment. The distance between the bottom of the upper esophageal sphincter and the top of the lower esophageal sphincter represents the length of the esophageal body and varies according to the height of the individual Fig. Anatomic Relations of the Esophagus Relationship of the Esophagus to the Hypopharynx The esophagus serves as a conduit from the pharynx to the stomach.
The pharyngeal musculature consists of three overlapping broad, flat, fan-shaped constrictors Fig. The superior constrictor arises mainly from the medial pterygoid plate, the middle constrictor arises from the hyoid bone, and the inferior constrictor arises from the thyroid and cricoid cartilages.
These muscles originate bilaterally, joining with their counterparts in the posterior midline to create a median posterior raphe. The upper orifice to the esophagus is collared by the cricopharyngeus muscle. This muscle originates from both edges of the cricoid cartilage and forms a continuous transverse muscle band without an interruption by a median posterior raphe.
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