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 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 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…
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 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 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…
The Nonneoplastic Esophagus Esophageal Development The esophagus develops from the cranial part of the primitive foregut, becoming recognizable at the 2.5-mm stage of development (approximately the third gestational week) as…
Changes Occurring in Intestinal Transplants Total intestinal transplantation is used to correct the short gut syndrome. Pediatric candidates for intestinal transplantation are those who undergo extensive intestinal resections for gastroschisis,…
Benign Lesions Presenting Clinically as Masses Various polyp types occur in the small intestine including lesions normally thought of as polyps, such as adenomas or Peutz-Jeghers polyps, as well as…
Pneumatosis Intestinalis Two forms of this relatively rare condition affect the intestines. The most common form affects patients with obstructive pulmonary disease and results from air dissection through the spaces…
