Table Of ContentNetter's Gastroenterology
2 th Edition Print Version Only
By Martin H. Floch, MD, Clinical Professor of Medicine, Section of Gastroenterology and
Nutrition, Yale University School of Medicine, Norwalk Hospital, Norwalk, CT and Neil R.
Floch; Edited by Kris V. Kowdley; C.S. Pitchumoni; James Scolapio and Raul Rosenthal
Section I: Esophagus
1. Topographic Relations of the Esophagus
2. Musculature of the Esophagus
3. Arterial Blood Supply of the Esophagus
4. Venous Drainage of the Esophagus
5. Innervation of the Esophagus: Parasympathetic and Sympathetic
6. Intrinsic Innervation of the Alimentary Tract
7. Histology of the Esophagus
8. Gastroesophageal Junction and Diaphragm
9. Deglutition
10. Neuroregulation of Deglutition
11. Congenital Anomalies of the Esophagus
12. Shatzki Ring
13. Plummer-Vinson Syndrome
14. Esophageal Dysmotility Disorders
15. Achalasia
16. Esophageal Diverticula
17. Foreign Bodies in the Esophagus
18. Caustic Injury of the Esophagus
19. Esophageal Rupture and Perforation
20. Esophageal Varicosities
21. Gastroesophageal Reflux Disease
22. Esophagitis: Acute and Chronic
23. Esophageal Ulcers
24. Eosinophilic Esophagitis
25. Benign Esophageal Stricture
26. Sliding and Paraesophageal Hiatal Hernias, Types 1, 2, 3
27. Barrett Esophagus
28. Benign Neoplasms of the Esophagus
29. Malignant Neoplasms: Upper and Middle Portions of the Esophagus
30. Malignant Neoplasms: Lower End of the Esophagus
Section II: Stomach and Duodenum
1. Anatomy of the Stomach: Normal Variations and Relations
2. Anatomy and Relations of the Duodenum
3. Mucosa of the Stomach
4. Duodenal Mucosa and Duodenal Structures
5. Blood Supply and Collateral Circulation of Upper Abdominal Organs
6. Lymphatic Drainage of the Stomach
7. Innervation of the Stomach and the Duodenum
8. Gastric Secretion
9. Factors Influencing Gastric Activity
10. Role of the Stomach in Digestion
11. Gastric Acid Secretion Tests: HCl and Gastrin
12. Effect of Drugs on Gastric Function
13. Upper Gastrointestinal Endoscopy: Esophagogastroduodenoscopy
14. Coated Tongue, Halitosis, and Thrush
15. Aerophagia and Eructation
16. Motility of the Stomach
17. Gastroparesis and Gastric Motility Disorders
18. Pyloric Obstruction and the Effects of Vomiting
19. Nausea and Vomiting
20. Hypertrophic Pyloric Stenosis
21. Diverticula of the Stomach and Gastrointestinal Prolapse
22. Diverticula of the Duodenum
23. Dyspepsia, Functional Dyspepsia and Nonulcer Dyspepsia
24. Helicobacter pylori Infection
25. Gastritis
26. Erosive Gastritis; Acute Gastric Ulcers
27. Peptic Ulcer Disease: Definition and Pathophysiology
28. Peptic Ulcer Disease: Duodenitis and Ulcer of the Duodenal Bulb
29. Peptic Ulcer Disease: Complications
30. Gastrointestinal Bleeding
31. Therapeutic Gastrointestinal Endoscopy
32. Benign Tumors of the Stomach
33. Gastric Lymphoma and MALT
34. Cancers of the Stomach
35. Tumors of the Duodenum
36. Principles of Gastric Surgery
37. Treatment of Morbid Obesity
38. Complications of Bariatric Surgery
39. Postgastrectomy Complications: Partial Gastrectomy
40. Effects of Total Gastrectomy
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Section III: Abdominal Wall
1. Anterolateral Abdominal Wall
2. Peritoneum
3. Pelvic Fascia and Perineopelvic Spaces
4. Inguinal Canal
5. Abdominal Regions and Planes
6. Abdominal Wall and Cavity: Congenital Abnormalities
7. Acute Abdomen
8. Alimentary Tract Obstruction
9. Mesenteric Vascular Occlusion
10. Other Vascular Lesions
11. Acute Peritonitis
12. Chronic Peritonitis
13. Cancer of the Peritoneum
14. Benign Paroxysmal Peritonitis (Familial Mediterranean Fever)
15. Abdominal Wounds of the Small Intestine
16. Abdominal Wounds of the Colon
17. Indirect and Direct Inguinal Hernias
18. Femoral Hernias
19. Abdominal Wall: Ventral Hernias
20. Lumbar, Obturator, Sciatic, and Perineal Hernias
21. Internal Hernias: Congenital Intraperitoneal Hernias
Section IV: Small Intestine
1. Topography of the Small Intestine
2. Gross Structure of the Small Intestine
3. Microscopic Structure of the Small Intestine
4. Terminal Ileum
5. Secretory, Digestive and Absorptive Functions of the Small Intestine
6. Gastrointestinal Hormones
7. Imaging of the Small Intestine
8. Vascular Supply and Drainage in the Small Intestine
9. Innervation of the Small and Large Intestines
10. Visceral Reflexes
11. Congenital Abnormalities of the Small Intestine
12. Meckel Diverticulum
13. Diverticula
14. Motility and Dysmotility of the Small Intestine
15. Obstruction and Ileus of the Small Intestine
16. Chronic Intestinal Pseudo-obstruction
17. Irritable Bowel Syndrome and Functional Gastrointestinal Disorders
18. Evaluation of the Small Bowel
19. Lactose Intolerance
20. Diarrhea
21. Celiac Disease and Malabsorption
22. Whipple Disease
23. Small Bacterial Intestinal Bacterial Overgrowth Syndrome(SIBO)
24. Short Bowel Syndrome
25. Food Allergy
26. Eosinophilic Gastroenteritis
27. Intussusception of the Small Intestine
28. Benign Tumors of the Small Intestine
29. Malignant Tumors of the Small Intestine
30. Carcinoid Syndrome and Neuroendocrine Tumors
31. Ileostomy, Colostomy, and Gastroenteric Stromas
Section V: Colon, Rectum, and Anus
1. Structure and Histology of the Colon
2. Sigmoid Colon
3. Rectum and Anal Canal
4. Vascular, Lymphatic, and Nerve Supply of the Large Intestine
5. Secretory, Digestive, and Absorptive Function of the Colon and Colonic Flora
6. Probiotics
7. Anoscopy, Sigmoidoscopy, and Colonoscopy
8. Laparoscopy
9. S
Topographic Relations
of the Esophagus
1
Neil R. Floch
T here is a smooth transition from the end of the pharynx, the esophagus. The lowest portion of the thoracic esophagus
at the level of the cricoid cartilage and the sixth cervical passes through the diaphragm into the abdomen.
vertebra (C6), to the esophagus (Figs. 1-1 and 1-2). On average, On the left side of the esophageal wall, in the upper thoracic
the esophagus is 40 cm (16 inches) long from the upper incisor region, is the ascending portion of the left subclavian artery and
teeth to the cardia of the stomach, but it may be as long as 43 cm the parietal pleura. At approximately the level of T4, the arch
in tall persons or in those with long trunks. The esophagus is of the aorta passes backward and alongside the esophagus.
divided, with the fi rst part extending 16 cm from the incisors to Below this, the descending aorta lies to the left, but when that
the lower border of the cricopharyngeus muscle and the rest vessel passes behind the esophagus, the left mediastinal pleura
extending 24 cm. again comes to adjoin the esophageal wall. On the right side,
The aortic arch crosses the esophagus from the left side and the parietal pleura is intimately applied to the esophagus, except
is located 23 cm from the incisors and 7 cm below the cricopha- when, at the level of T4, the azygos vein intervenes as it turns
ryngeus muscle; 2 cm below this level, the left main bronchus forward.
crosses in front of the esophagus. The lower esophageal sphinc- In the upper thorax, the esophagus lies on the longus colli
ter (LES) begins 37 to 38 cm from the incisors. The esophageal muscle, the prevertebral fascia, and the vertebral bodies. At the
hiatus is located 1 cm below this point, and the cardia of the eighth thoracic vertebra (T8), the aorta lies behind the esopha-
stomach is yet lower. In children the dimensions are propor- gus. The azygos vein ascends behind and to the right of the
tionately smaller. At birth the distance from the incisor teeth to esophagus as far as the level of T4, where it turns forward. The
the cardia is approximately 18 cm; at 3 years, 22 cm; and at hemiazygos vein and the fi ve upper-right intercostal arteries
10 years, 27 cm. cross from left to right behind the esophagus. The thoracic duct
Like a “good soldier,” the esophagus follows a left-right-left ascends to the right of the esophagus before turning behind it
path as it marches down the anteroposterior curvature of the and to the left at the level of T5. The duct then continues to
vertebral column. It descends anterior to the vertebral column, ascend on the left side of the esophagus.
through the lower portion of the neck and the superior and A small segment of abdominal esophagus lies on the crus of
posterior mediastinum. The esophagus forms two lateral curves the diaphragm and creates an impression in the underside of
that, when viewed anteriorly, appear as a reverse S: the upper the liver. Below the tracheal bifurcation, the esophageal nerve
esophagus has a convex curve toward the left, and the lower plexus and the anterior and posterior vagal trunks adhere to the
esophagus has a convex curve toward the right. At its origin, the esophagus.
esophagus bends 1/ inch (0.6 cm) to the left of the tracheal As the esophagus travels from the neck to the abdomen, it
4
margin. It crosses the midline behind the aortic arch at the level encounters several indentations and constrictions. The fi rst nar-
of the fourth thoracic vertebra (T4). The esophagus then turns rowing occurs at the cricopharyngeus muscle and the cricoid
to the right at the seventh thoracic vertebra (T7), after which it cartilage. The aortic arch creates an indentation on the left side
turns sharply to the left as it enters the abdomen through the of the esophagus, and the pulsations of the aorta may be seen
esophageal hiatus of the diaphragm, to join the cardia of the during esophagoscopy. Below this point, the left main bronchus
stomach at the gastroesophageal (GE) junction. creates an impression on the left anterior aspect of the esopha-
The esophagus is composed of three segments: cervical, tho- gus. The second narrowing occurs at the LES.
racic, and abdominal. Anterior to the cervical esophagus is the Although the esophagus is described as a “tube,” it is oval
membranous wall of the trachea. Loose areolar tissue and mus- and has a fl at axis anterior to posterior with a wider transverse
cular strands connect the esophagus and the trachea, and recur- axis. When the esophagus is at rest, its walls are approximated
rent laryngeal nerves ascend in the grooves between them. and its width is 2 cm, but it distends and contracts depending
Posterior to the esophagus are the longus colli muscles, the on its state of tonus.
prevertebral fascia, and the vertebral bodies. Although the
cervical esophagus is positioned between the carotid sheaths, it ADDITIONAL RESOURCES
is closer to the left carotid sheath. The thyroid gland partially
Cameron JL, editor: Current surgical therapy, ed 6, St Louis, 1998, Mosby,
overlaps the esophagus on both sides. pp 1-74.
The thoracic esophagus lies posterior to the trachea. It extends
Gray H, Bannister LH, Berry MM, Williams PL, editors: Gray’s anatomy:
down to the level of the fi fth thoracic vertebra (T5), where the
the anatomical basis of medicine and surgery, New York, 1995, Churchill
trachea bifurcates. The trachea curves to the right as it divides, Livingstone.
and thus the left main bronchus crosses in front of the esopha-
Peters JH, DeMeester TR: Esophagus and diaphragmatic hernia. In
gus. Below this, the pericardium separates the esophagus from Schwartz SI, Shires TG, Spencer FC, editors: Principles of surgery, ed 7,
the left atrium of the heart, which lies anterior and inferior to New York, 1999, McGraw-Hill, pp 1081-1179.
4 SECTION I • Esophagus
T2
T3
T4
T5
T6
Left crus
Right crus
T7
Esophagus
Aorta
T8
Esophagus
T9
Diaphragm
Esophageal hiatus (T10)
Gastric fundus
Left vagal trunk
Esophagogastric junction (T11)
Right crus of diaphragm
Left crus of diaphragm
Median arcuate ligament
Aortic opening (T12)
L1
Aorta
L2
Duodenum
Figure 1-1 Regional Anatomy of Diaphragm, Stomach, and Esophagus.
CHAPTER 1 • Topographic Relations of the Esophagus 5
Incisor teeth
0
Inferior pharyngeal
constrictor muscle
Oropharynx Thyroid cartilage
Epiglottis
Cricoid cartilage
Piriform fossa
C4
Cricopharyngeus
Thyroid cartilage (muscle) part of
Pharyngo- inferior C6
esophageal
pharyngeal
constriction Cricoid cartilage
constrictor
T1
16
Cricopharyngeus Trachea
(muscle) part of
inferior Esophagus
ers pharyngeal T3
et Thoracic constrictor Arch of aorta
m (aortobronchial) 2
enti constriction Trachea Sternum
c T5
gth in 23 Arch of aorta 3
n
e le 4 Heart in T7
ag Left main pericardium
er bronchus
v
A 5
T9
6
7
T11
Diaphragm
Diaphragmatic Lateral view L1
constriction
(inferior Diaphragm
esophageal
“sphincter”)
38
Abdominal part L3
40of esophagus Fundus of stomach
Cardiac part
of stomach
Figure 1-2 Topography and Constrictions of Esophagus.
Musculature of the Esophagus
2
Neil R. Floch
T he esophagus is composed of outer longitudinal and inner The inner, circular, muscle layer is thinner than the outer
circular muscle layers (Figs. 2-1 and 2-2). On the vertical longitudinal layer. This relationship is reversed in all other parts
ridge of the dorsal aspect of the cricoid cartilage, two tendons of the gastrointestinal (GI) tract. In the upper esophagus, the
originate as they diverge and descend downward around the circular muscle closely approximates the encircling lower fi bers
sides of the esophagus to the dorsal aspect. These tendons weave of the cricopharyngeus muscle. The upper esophageal fi bers are
in the midline of the ventral area, creating a V-shaped gap not circular but elliptical, with the anterior part of the ellipse at
between the two muscles known as the V-shaped area of Laimer. a lower level of the posterior part. The ellipses become more
This gap, or bare area, exposes the underlying circular muscle. circular as the esophagus descends, until the start of its middle
Located above this area is the cricopharyngeus muscle. Sparse third, where the fi bers run in a horizontal plane. In one 1-cm
longitudinal muscles cover the area, as do accessory fi bers from segment, the fi bers are truly circular. Below this point, the fi bers
the lower aspect of the cricopharyngeus muscle. become elliptical once again, but they now have a reverse incli-
In the upper esophagus, longitudinal muscles form bundles nation; that is, the posterior part of the ellipse is located at a
of fi bers that do not evenly distribute over the surface. The lower level than the anterior part. In the lower third of the
thinnest layers of muscle are anterior and adjacent to the pos- esophagus, the fi bers follow a spiral course down the esophagus.
terior wall of the trachea. The longitudinal muscle of the esoph- The elliptical, circular, and spiral fi bers of this layer are not truly
agus receives fi bers from an accessory muscle on each side that uniform and parallel but may overlap and cross, or they may
originates from the posterolateral aspect of the cricoid cartilage even have clefts between them. Some fi bers in the lower two
and the contralateral side of the deep portion of the cricopha- thirds of the esophagus pass diagonally or perpendicularly, up
ryngeus muscle. As the longitudinal muscle descends, its fi bers or down, joining fi bers at other levels. These branched fi bers
become equally distributed and completely cover the surface of are 2 to 3 mm wide and 1 to 5 cm long and are not
the esophagus. continuous.
Inferior pharyngeal constrictor muscle
Thyroid cartilage Pharyngeal raphe
Zone of sparse muscle fibers
Cricopharyngeus (muscle) part of inferior pharyngeal constrictor
Main longitudinal muscle bundle passing upward and ventrally
to attach to middle of posterior surface of cricoid cartilage
Accessory muscle bundle from posterolateral surface of cricoid cartilage
Cricoid cartilage
Additional fibers from contralateral side of cricopharyngeus
(muscle) part of inferior pharyngeal constrictor
Hook
Circular muscle layer with sparse longitudinal
fibers in V-shaped area (Laimer)
Trachea
Bare area on ventral surface of esophagus
Lateral mass of longitudinal muscle
Fibroelastic membranes with sparse muscle fibers
Window cut in longitudinal muscle layer
Circular muscle layer
Left main bronchus
Figure 2-1 Musculature of the Esophagus.
CHAPTER 2 • Musculature of the Esophagus 7
Superior pharyngeal constrictor muscle
Root of tongue
Epiglottis
Middle pharyngeal
constrictor muscle
Palatopharyngeus
muscle
Longitudinal pharyngeal muscles
Stylopharyngeus
muscle
Pharyngoepiglottic fold
Laryngeal inlet (aditus)
Thyroid cartilage (superior horn)
Thyrohyoid membrane
Internal branch of superior
laryngeal nerve and superior
laryngeal artery and vein
Oblique arytenoid muscle
Transverse arytenoid muscle
Thyroid cartilage
Posterior cricoarytenoid muscle
Inferior pharyngeal constrictor muscle
Pharyngeal aponeurosis (cut away)
Zone of sparse muscle fibers
Cricopharyngeus (muscle) part of inferior
pharyngeal constrictor
Cricoid cartilage (lamina)
Posterior view with Cricoesophageal tendon
pharynx opened and (attachment of longitudinal esophageal muscle)
mucosa removed
Circular esophageal muscle
Esophageal mucosa and submucosa
Circular muscle in V-shaped area (Laimer)
Right recurrent laryngeal nerve
Longitudinal esophageal muscle
Window cut in longitudinal muscle exposes circular muscle layer
Figure 2-2 Pharyngoesophageal Junction.
The cricopharyngeus muscle marks the transition from The upper 25% to 33% of the esophagus is composed of
pharynx to esophagus. It is the lowest portion of the inferior striated muscle, whereas the lower or remaining portion is
constrictor of the pharynx and consists of a narrow band of smooth muscle. Within the second fourth of the esophagus is a
muscle fi bers that originate on each side of the posterolateral transitional zone where striated muscle and smooth muscle are
margin of the cricoid cartilage. The cricopharyngeus then passes present. The lower half contains purely smooth muscle. Between
slinglike around the dorsal aspect of the pharyngoesophageal the two muscular coats of the esophagus, a narrow layer of con-
(PE) junction. Upper fi bers ascend and join the median raphe nective tissue is inserted that accommodates the myenteric
of the inferior constrictor muscle posteriorly. Lower fi bers do plexus of Auerbach.
not have a median raphe; they pass to the dorsal aspect of the
PE junction. A few of these fi bers pass down to the esophagus. ADDITIONAL RESOURCES
The cricopharyngeus functions as a sphincter of the upper
Gray H, Bannister LH, Berry MM, Williams PL, editors: Gray’s anatomy:
esophagus. Muscle tone of the esophageal lumen is greatest at
the anatomical basis of medicine and surgery, New York, 1995, Churchill
the level of the cricopharyngeus, and relaxation of this muscle Livingstone.
is an integral part of the act of swallowing. There is a weak area
Peters JH, DeMeester TR: Esophagus and diaphragmatic hernia. In
between the cricopharyngeus and the main part of the inferior Schwartz SI, Shires TG, Spencer FC, editors: Principles of surgery, ed 7, New
constrictor where Zenker diverticula are thought to develop. York, 1999, McGraw-Hill, pp 1081-1179.
Arterial Blood Supply of
the Esophagus
3
Neil R. Floch
T he blood supply of the esophagus is variable (Fig. 3-1). The abdominal esophagus receives its blood supply from
The inferior thyroid artery is the primary supplier of the branches of the left gastric artery, the short gastric artery, and
cervical esophagus; esophageal vessels emanate from both side a recurrent branch of the left inferior phrenic artery. The left
branches of the artery and from the ends of the vessels. Anterior gastric artery supplies cardioesophageal branches either through
cervical esophageal arteries supply small branches to the esopha- a single vessel that subdivides or through two to fi ve branches
gus and trachea. Accessory arteries to the cervical esophagus before they divide into anterior and posterior gastric branches.
originate in the subclavian, common carotid, vertebral, ascend- Other arterial sources to the abdominal esophagus are (1)
ing pharyngeal, superfi cial cervical, and costocervical trunk. branches from an aberrant left hepatic artery, derived from the
Arterial branches from the bronchial arteries, the aorta, and left gastric, an accessory left gastric from the left hepatic, or a
the right intercostal vessels supply the thoracic esophagus. persistent primitive gastrohepatic arterial arc; (2) cardioesopha-
Bronchial arteries, especially the left inferior artery, distribute geal branches from the splenic trunk, its superior polar, terminal
branches at or below the tracheal bifurcation. Bronchial artery divisions (short gastrics), and its occasional, large posterior
branches are variable. The standard—two left and one right— gastric artery; and (3) a direct, slender, cardioesophageal branch
occurs in only about 50% of patients. Aberrant vessel patterns from the aorta, celiac, or fi rst part of the splenic artery.
include one left and one right in 25% of patients, two right and With every resection surgery, areas of devascularization
two left in 15%, and one left and two right in 8%. Rarely do may be induced by (1) excessively low resection of the cervical
three right or three left arteries occur. segment, which always has a supply from the inferior thyroid;
At the tracheal bifurcation, the esophagus receives branches (2) excessive mobilization of the esophagus at the tracheal bifur-
from the aorta, aortic arch, uppermost intercostal arteries, inter- cation and laceration of the bronchial artery; and (3) excessive
nal mammary artery, and carotid artery. Aortic branches to the sacrifi ce of the left gastric artery and the recurrent branch of
thoracic esophagus usually consist of two unpaired vessels. The the inferior phrenic artery to facilitate gastric mobilization.
cranial vessel is 3 to 4 cm long and usually arises at the level of Anastomosis around the abdominal portion of the esophagus is
the sixth to seventh thoracic vertebrae (T6-T7). The caudal usually copious, but sometimes it is limited.
vessel is longer, 6 to 7 cm, and arises at the level of T7 to T8.
Both arteries pass behind the esophagus and divide into ascend- ADDITIONAL RESOURCES
ing and descending branches. These branches anastomose along
Gray H, Bannister LH, Berry MM, Williams PL, editors: Gray’s anatomy:
the esophageal border with descending branches from the infe-
the anatomical basis of medicine and surgery, New York, 1995, Churchill
rior thyroid and bronchial arteries, as well as with ascending Livingstone.
branches from the left gastric and left inferior phrenic arteries.
Peters JH, DeMeester TR: Esophagus and diaphragmatic hernia. In
Right intercostal arteries, mainly the fi fth, give rise to esopha- Schwartz SI, Shires TG, Spencer FC, editors: Principles of surgery, ed 7, New
geal branches in approximately 20% of the population. York, 1999, McGraw-Hill, pp 1081-1179.
