**3. Narrowings and curves of esophagus**

Esophagus has seven narrowing points that can be seen using esophagoscopy or barium passage graphy. Four classic narrowings are found in almost all people; three other narrowings are found in certain medical conditions.

First classical narrowing is at the beginning point, and oropharyngeal muscle forms it; this part is the second narrowest point after orifice of appendix vermiformis in alimentary tract. This first narrowing point's luminal diameter is approximately 1.4–1.5 cm, and it is located 15 cm after maxillary central incisor teeth. Topographically, this first point corresponds to corpus of 6th cervical vertebra. This narrowing is named "upper esophageal sphincter." Second narrowing corresponds to plane that is located at superior border of sternum. Anterior and posterior esophageal walls become closer in hyperflexion, and this partial narrowing point occurs. Third narrowing is one of classical narrowings made by aortic arch. This point corresponds to 4th thoracic vertebra topographically and measures 1.5–1.6 cm in width. Point is located 22.5 cm after maxillary central incisor teeth, 7 cm below cricopharyngeus muscle [2]. Fourth narrowing (third classical narrowing) is located at crossing point of esophagus and left main bronchium. This point is located at level of 5th dorsal vertebra, and 27.5 cm after maxillary central incisor teeth and 9 cm below oropharyngeal muscle. Fifth narrowing point is formed if patient has atrial dilatation caused by mitral stenosis. This point is located just below bronchial narrowing. Sixth narrowing, called "Laimer narrowing," is located at second crossing point of esophagus and aorta. This point is located at plane corresponding to upper edge of 10th dorsal vertebral corpus. Laimer narrowing occurs in situation of aortic atherosclerosis. Just above this narrowing, a partial dilatation called "epiphrenic ampulla" or "Vorgamen de Luschka" is found. Last narrowing (and 4th classical narrowing) is made by esophageal hiatus that originates from right crus of diaphragm, and is located at the level of 11th dorsal vertebra and 40 cm after maxillary central incisor teeth; it is 1–1.5 cm in length and1.5–1.8 cm in width. This last narrowing is named "lower esophageal sphincter." Lower sphincter consists of a physiological sphincter mechanism made by muscle fibers of right crus of diaphragm; it provides an antireflux mechanism. When a person is not eating, esophageal lumen is closed above lower esophageal sphincter. Esophagus is primarily median and vertical, but has three slight curves located in neck, behind left bronchus, and at bifurcation of trachea (**Picture 1**).

Esophagus is located at left of midline at level of 1st dorsal vertebra, right of midline at level of 6th dorsal vertebra, and left of midline again at level of 10th dorsal vertebra. Thus, esophagus makes a reverse "S" all the way in front of vertebral column. These narrowings and curves are important landmarks for radiological and endoscopic investigation of abnormalities, cancer diagnosis, and stricture formation after swallowing of chemicals [2, 7].

Esophagus is anatomically divided into three parts: cervical esophagus, thoracic esophagus, and abdominal esophagus.

#### **3.1. Cervical esophagus**

Cervical esophagus starts at inferior margin of cricoid cartilage that corresponds to corpus of 6th cervical vertebra. This level is marked by a carotid tubercula named "Chasseing tubercula,"

**Picture 1.** Endoscopic view of esophagus (with the permission of Turkish Surgery Association).

which is an important landmark in cervical esophagectomy. Cervical esophagus ends at inferior edge of first dorsal vertebra that comes up to a horizontal plane of jugular incisura of sternum. The endpoint is the starting point of upper mediastinum, and from this point it is thoracic esophagus. Cervical esophagus is 5–6 cm long, and its luminal diameter is 1.4–1.5 cm at its narrowest point.

#### *3.1.1. Surrounding structures*

**3. Narrowings and curves of esophagus**

are found in certain medical conditions.

6 Esophageal Abnormalities

Esophagus has seven narrowing points that can be seen using esophagoscopy or barium passage graphy. Four classic narrowings are found in almost all people; three other narrowings

First classical narrowing is at the beginning point, and oropharyngeal muscle forms it; this part is the second narrowest point after orifice of appendix vermiformis in alimentary tract. This first narrowing point's luminal diameter is approximately 1.4–1.5 cm, and it is located 15 cm after maxillary central incisor teeth. Topographically, this first point corresponds to corpus of 6th cervical vertebra. This narrowing is named "upper esophageal sphincter." Second narrowing corresponds to plane that is located at superior border of sternum. Anterior and posterior esophageal walls become closer in hyperflexion, and this partial narrowing point occurs. Third narrowing is one of classical narrowings made by aortic arch. This point corresponds to 4th thoracic vertebra topographically and measures 1.5–1.6 cm in width. Point is located 22.5 cm after maxillary central incisor teeth, 7 cm below cricopharyngeus muscle [2]. Fourth narrowing (third classical narrowing) is located at crossing point of esophagus and left main bronchium. This point is located at level of 5th dorsal vertebra, and 27.5 cm after maxillary central incisor teeth and 9 cm below oropharyngeal muscle. Fifth narrowing point is formed if patient has atrial dilatation caused by mitral stenosis. This point is located just below bronchial narrowing. Sixth narrowing, called "Laimer narrowing," is located at second crossing point of esophagus and aorta. This point is located at plane corresponding to upper edge of 10th dorsal vertebral corpus. Laimer narrowing occurs in situation of aortic atherosclerosis. Just above this narrowing, a partial dilatation called "epiphrenic ampulla" or "Vorgamen de Luschka" is found. Last narrowing (and 4th classical narrowing) is made by esophageal hiatus that originates from right crus of diaphragm, and is located at the level of 11th dorsal vertebra and 40 cm after maxillary central incisor teeth; it is 1–1.5 cm in length and1.5–1.8 cm in width. This last narrowing is named "lower esophageal sphincter." Lower sphincter consists of a physiological sphincter mechanism made by muscle fibers of right crus of diaphragm; it provides an antireflux mechanism. When a person is not eating, esophageal lumen is closed above lower esophageal sphincter. Esophagus is primarily median and vertical, but has three slight curves located in neck, behind left bronchus, and at bifurcation of trachea (**Picture 1**).

Esophagus is located at left of midline at level of 1st dorsal vertebra, right of midline at level of 6th dorsal vertebra, and left of midline again at level of 10th dorsal vertebra. Thus, esophagus makes a reverse "S" all the way in front of vertebral column. These narrowings and curves are important landmarks for radiological and endoscopic investigation of abnormalities, cancer

Esophagus is anatomically divided into three parts: cervical esophagus, thoracic esophagus,

Cervical esophagus starts at inferior margin of cricoid cartilage that corresponds to corpus of 6th cervical vertebra. This level is marked by a carotid tubercula named "Chasseing tubercula,"

diagnosis, and stricture formation after swallowing of chemicals [2, 7].

and abdominal esophagus.

**3.1. Cervical esophagus**

Esophagus runs in deepest fascial plane of neck, leaning between trachea anteriorly and vertebra posteriorly. Esophagus is attached to prevertebral fascia by sagittal septa, which forms retropharyngeal and retro-esophagial spaces.

Esophagus is covered by larynx and trachea anteriorly (**Figure 3**), but this covering is partial, and an open margin is found on left anterior side, which provides natural surgical access. Esophagus attaches with tracheoesophageal muscle fibers to trachea; it is easy to separate tracheoesophageal plane, except in pathological circumstances. Esophagus's closest structure is carotid artery anterolaterally, which lies 1–2 cm away from it. Inferior thyroid artery, thyroid lobes, and recurrent laryngeal nerves are other important contiguities of esophagus, and ductus thoracicus lies on left side of it. Esophagus connects prevertebral muscles, cervical vertebras, and prevertebral laminas posteriorly. Thoracic duct connects to left "Pirogoff angle," and it makes a slight connection to left side of esophagus.

#### *3.1.2. Importance of surrounding structures*

Sagittal septa, which forms retropharyngeal and retro-esophagial spaces, blocks the diffusion of abscess of this area to upper mediastinum, but abscess can diffuse via pretracheal space to the upper mediastinum and can cause a fatal complication. Pretracheal space is important in that it can be perforated, primarily during an esophagectomy.

**Figure 3.** Placement of esophagus relative to other anatomic structures (with permission of Turkish Surgery Association).

Recurrent laryngeal nerve (RLN) lies in tracheoesophageal sulcus, and esophagus is close to this nerve, which is important in case of cervical esophagectomy. Injury of RLN causes unilateral difficulty in swallowing and hoarseness; bilateral injury causes closure of vocal cords in median position, and a tracheostomy becomes necessary. Especially on left side of esophagus, RLN is so close to esophagus that it is easy to injure a nerve with a careless dissection. Thus, dissection should be made close to esophageal muscle fibers to avoid this complication. As previously mentioned, thoracic duct connects to left Pirogoff angle, and it makes a slight connection to left side of esophagus. To avoid harm to thoracic duct, a careful dissection should be made, especially in cervical esophagectomy [8, 9].

#### **3.2. Thoracic esophagus**

Measuring 16–18 cm in length, thoracic esophagus is in upper and posterior mediastinum. Running from 1st to 11th dorsal vertebra, it does not fit concavity of vertebral column. However, it changes location to left gradually from start to end. 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].

**Figure 4.** Arteries of Esophagus.

Recurrent laryngeal nerve (RLN) lies in tracheoesophageal sulcus, and esophagus is close to this nerve, which is important in case of cervical esophagectomy. Injury of RLN causes unilateral difficulty in swallowing and hoarseness; bilateral injury causes closure of vocal cords in median position, and a tracheostomy becomes necessary. Especially on left side of esophagus, RLN is so close to esophagus that it is easy to injure a nerve with a careless dissection. Thus, dissection should be made close to esophageal muscle fibers to avoid this complication. As previously mentioned, thoracic duct connects to left Pirogoff angle, and it makes a slight connection to left side of esophagus. To avoid harm to thoracic duct, a careful dissection should

**Figure 3.** Placement of esophagus relative to other anatomic structures (with permission of Turkish Surgery Association).

Measuring 16–18 cm in length, thoracic esophagus is in upper and posterior mediastinum. Running from 1st to 11th dorsal vertebra, it does not fit concavity of vertebral column. However, it changes location to left gradually from start to end. 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].

be made, especially in cervical esophagectomy [8, 9].

**3.2. Thoracic esophagus**

8 Esophageal Abnormalities

As previously discussed, esophagus within thoracic cavity contains three classical narrowings, two conditional narrowings, and two curves.

#### *3.2.1. Surrounding structures*

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.

#### *3.2.2. Importance of surrounding structures*

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.

At a level of diaphragmatic hiatus, a soft areolar tissue connects esophagus to diaphragmatic cruses, and a slight concave area called "portal concavity" allows formation of a hiatal hernia.

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].

#### **3.3. Abdominal esophagus**

Abdominal esophagus is 1–2.5 cm long and is topographically located at 11thvertebral plane posteriorly. 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.

#### *3.3.1. Surrounding structures*

Following structures are located near abdominal esophagus: posterior side segment of twothirds 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. Before reaching hiatus, esophagus dilatates at a place called "epithetic ampulla" that is delaying point of morsel when swallowing during radiologic examinations.

Esophagus ends at a place called "cardia of stomach." Right side of esophagus continues as lesser curvate of stomach, and left side angles with greater curvate of stomach, forming "angle of Hiss." A mucosal tongue that descends into stomach is called "Gubaroff valvula." Hiss angle and Gubaroff valvula are important in antireflux mechanism [11].

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,

**Figure 5.** Veins of Esophagus.

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,

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

At a level of diaphragmatic hiatus, a soft areolar tissue connects esophagus to diaphragmatic cruses, and a slight concave area called "portal concavity" allows formation of a hiatal hernia. 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 azy-

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

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 1–2.5 cm long and is topographically located at 11thvertebral plane posteriorly. 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 twothirds 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

gos vein block tumors in these areas to infiltrate lower parts of mediastinum.

dissection and resection easier and tumor infiltration more difficult in this area.

and right vagus nerve are located on right side.

*3.2.2. Importance of surrounding structures*

should be performed in this area.

10 Esophageal Abnormalities

**3.3. Abdominal esophagus**

*3.3.1. Surrounding structures*

side, and fundus of stomach at left side.

phrenoesophageal fascia, and transverse fascia of abdomen and peritoneum. Fibers of this ligament that reach upward are called "Juvara fibers"; downward fibers are called "Rouget fibers." Phrenoesophageal ligament resists vigorous abdominal pressure that pushes stomach to intrathoracic cavity, but it allows esophagus to move upward and downward while swallowing. This ligament makes gastroesophageal junction both flexible and tight [12, 13].
