Digestive System

Derivatives of Caudal Part of Foregut(Page 77)

Folding of the embryo leads to formation of the gut (foregut in head fold, hindgut in tail fold and midgut inbetween). Ventral & dorsal mesentery are formed also. Foregut forms, pharynx, respiratory system, esophagus, stomach and upper part of duodenum with related organs like liver and pancreas. Midgut forms rest of small intestine, large intestine till right 2/3 of transverse colon. It is connected with defenitive yolk sac by vitello-intestinal duct. Hind gut forms rest of digestive system and uro-genital derivatives.

Formation of Mesentry

Development of Esophagus(page 77)

Development of Esophagus

It develops from foregut caudal to laryngo-tracheal groove till stomach. Firstly it is very short, then elongate after descend of the heart. Muscles of esophagus are developed from surrounding mesoderm.

Dr. Sherif Fahmy

Dr. Sherif Fahmy

Congenital Anomalies

Anatomy of Stomach

Development of StomachPage 79

Developmet of Stomach

Final Shape of Stomach

Steps of stomach development
It starts at the 5th week by a fusiform dilatation which has: Upper and lower narrow ends. Anterior and posterior borders which are connected to anterior and posterior abdominal walls by ventral and dorsal mesogastrium. Right and left surfaces which are covered with peritoneum. -This is followed by rapid growth of posterior border to form greater curvature while the anterior border forms lesser curvature.


Liver is formed in ventral mesentery, spleen is formed in dorsal mesentery. Rotation of stomach to the right (clockwise) for 90 degrees. Results of rotation: 1- Lesser curvature is directed to the right, while greater curvature is directed to left. 2- Left surface is directed anteriorly, right surface is directed posteriorly. 3- Formation of a peritoneal sac behind the stomach, called lesser sac. 4- Left & right vagi will be anterior and posterior gastric nerves.



5- Ventral mesogastrium forms lesser omentum, capsule around liver, falciform ligament and coronary ligaments. 6- Dorsal mesogastrium forms gastrophrenic, gastrosplenic, lienorenal ligaments and greater omentum. N.B. Stomach is supplied by artery of foregut which is celiac trunk.

Congenital Anomalies

1- Pyloric stenosis: Congenital narrowing of pyloric orifice. 2- Hour glass stomach: constriction of stomach dividing it into 2 dilated parts with a narrowing inbetween. 3- Thoracic stomach: Protrusion of upper part of stomach through diaphragm due to short esophagus.


1- Enumerate the branches of external carotid artery. 2- Name the tributaries of internal jugular vein.