Innervation
Innervation Like other portions of the gut, the large bowel is innervated by the autonomic nervous system. Parasympathetic nerves stimulate colonic motor activity, whereas sympathetic nerves inhibit motility and decrease…
Embryology
Embryology The embryologic midgut gives rise to the proximal colon, including the cecum, the ascending colon, and the first two thirds of the transverse colon. The rest of the colon…
Introduction
Introduction The large intestine is divided into the appendix; the cecum; the ascending, transverse, descending, and sigmoid colon; and the rectum (Fig. 13.1). Since both the appendix and the anus…
Motility Disorders
Motility Disorders Introductory Comments Normal gastrointestinal (GI) motility depends on intact neuromuscular functions that consist of both intrinsic and extrinsic innervation. Extrinsic control of peristalsis includes the sympathetic (thoracolumbar) and…
Nonneoplastic Diseases of the Appendix
Nonneoplastic Diseases of the Appendix Normal Embryonic Development The cecum appears during the fifth fetal week, arising as a diverticulum from the distal primitive intestinal loop before it differentiates into…
The Neoplastic Appendix
The Neoplastic Appendix Appendiceal tumors constitute <0.4% of all intestinal neoplasms. They pathologically resemble their small and large intestinal counterparts. The most significant difference between appendiceal and intestinal neoplasms is…
Online Chapter 1
Online Chapter 1 CASE 1.1 CLINICAL HISTORY 46-year-old man with dysphagia. FIGURE 1.1A FIGURE 1.1B FINDINGS Frontal and lateral radiographs (A, B) obtained at the conclusion of a barium swallow…
Epithelial Tumors of the Small Intestine
Epithelial Tumors of the Small Intestine General Features of Small Intestinal Tumors Benign and malignant small intestinal tumors are uncommon. Most small bowel malignancies are metastases from tumors arising elsewhere…
The Nonneoplastic Stomach
The Nonneoplastic Stomach Embryology The stomach develops from a fusiform foregut swelling at approximately 4 weeks’ gestation. It originates in the neck and descends into the abdomen during the next…
Infectious Diseases
Infectious Diseases Mechanisms of Bacterial Injury Numerous factors predispose to microbial intestinal colonization and contribute to diarrhea, malnutrition, sepsis, and extraintestinal infections. Vigorous peristaltic forward propulsion of intestinal contents into…
