tailieunhanh - Ebook Netter's atlas of human embryology (update edition): Part 2

(BQ) Part 2 book "Netter's atlas of human embryology" presents the following contents: The gastrointestinal system and abdominal wall, the urogenital system, the musculoskeletal system, head and neck. | Chapter 6 THE GASTROINTESTINAL SYSTEM AND ABDOMINAL WALL TIMELINE Primordium The foregut midgut and hindgut and their associated organs are derived from splanchnopleure endoderm and splanchnic mesoderm of the lateral plate . Plan for the Gastrointestinal GI System Perhaps nowhere in the body is the organization of an organ system so simple in the embryo and its appearance so complex in the adult. The GI system in the abdomen first develops as a tube suspended by dorsal and ventral sheetlike mesenteries. Blood vessels autonomic nerves lymphatic drainage and mesentery structure are all organized according to abdominal foregut midgut and hindgut subdivisions of the GI tract. These basic relationships persist but the adult anatomy appears complex because of four developments 1 rotation of the abdominal foregut tube 90 degrees clockwise 2 development of the greater omentum and lesser peritoneal sac from the dorsal mesentery of the abdominal foregut 3 rotation of the midgut 270 degrees around the superior mesenteric artery and 4 tremendous growth of the midgut intestines. Plan for the Inguinal Canal The testis begins development between parietal peritoneum and the muscles and fascia of the abdominal wall but must end up in the scrotum an evagination of the superficial body wall. The testis forms the inguinal canal by pushing its way through the deep body wall. The layers of the wall contribute to the coverings of the spermatic cord of vessels nerves and lymphatics supplying the testis. 1 month Thyroid lung liver and pancreas buds from the à foregut appear. The I ventral mesentery of the midgut and hindgut breaks down. Theyolksac begins to get compressed into the umbilical cord. Prenatal Time Scale Months Embryo 2 2 months Midgut loop extends into the umbilical cord. The lesser peritoneal sac begins to develop from the dorsal mesogastrium. Midgut begins to grow in the umbilical cord and rotate 270 degrees around the superior mesenteric artery. 6 weeks 8 months Abdominal .