Gastrointestinal System 1: Anatomy Overview

The bony boundaries of the oral cavity are the mandible and palatine bones.

The tongue is a muscular organ responsible for taste, speech, and swallowing.

Teeth are essential for chewing and breaking down food.

The hard palate forms the roof of the mouth, while the soft palate is the fleshy part in the back.

The epiglottis prevents food from entering the trachea during swallowing.

The parotid duct, also known as Stensen's duct, opens into the mouth opposite the upper second molar.

The muscles of mastication are responsible for chewing.

The temporalis, masseter, medial, and lateral pterygoid muscles are all innervated by the trigeminal nerve (CN V).

The nasopharynx, oropharynx, and laryngopharynx are the three parts of the pharynx.

The soft palate closes off the nasopharynx during swallowing to prevent food from going up the nose.

The epiglottis marks the division between the oropharynx and laryngopharynx.

The larynx is located anterior to the laryngopharynx.

The oesophagus is a muscular tube that carries food from the pharynx to the stomach.

The oesophagus is surrounded by the oesophageal plexus, which contains branches of the vagus nerve and sympathetic trunk.

The left vagus nerve courses anterior to the oesophagus as it passes through the diaphragm, while the right vagus courses posterior.

The oesophagus passes through the diaphragm at the level of the T10 vertebra.

The stomach is a muscular organ responsible for storing and mixing food.

The lower oesophageal sphincter is maintained by the angle of the gastroesophageal junction, the diaphragm, and the surrounding muscles.

The fundus, body, pyloric antrum, greater and lesser curvature, anterior and posterior surfaces, rugae, cardia, incisura angularis, and pyloric sphincter are all features of the stomach.

The pylorus, a thick muscular ring, controls the flow of food from the stomach to the duodenum.

The lesser omentum is a double layer of peritoneum that connects the liver to the stomach.

The omental bursa (lesser sac) is a pouch of peritoneum behind the lesser omentum.

The duodenum is the first part of the small intestine and is divided into four parts: superior, descending, horizontal, and ascending.

The pancreas is enclosed within the C-shape of the duodenum.

The duodenum is mostly retroperitoneal, meaning it is located behind the peritoneum.

The coeliac trunk is the first anterior midline branch of the abdominal aorta and supplies the foregut.

The splenic artery supplies the spleen, pancreas, and part of the stomach.

The left gastric artery supplies the stomach and oesophagus.

The common hepatic artery supplies the liver, gallbladder, and duodenum.

The duodenojejunal flexure is the junction between the duodenum and jejunum.

The ligament of Treitz, also known as the suspensory ligament of the duodenum, supports the duodenojejunal flexure.

The greater sac is the main compartment of the peritoneal cavity.

The root of the mesentery is the attachment of the small intestine to the posterior abdominal wall.

The jejunum and ileum are intraperitoneal, meaning they are located within the peritoneal cavity.

Peyer's patches are clusters of lymphoid tissue in the ileum that help fight infection.

The ileum terminates at the ileocecal valve, which connects to the cecum and ascending colon.

The superior mesenteric artery supplies blood to the midgut, including much of the small intestine.

The lymph vessels called lacteals in the small intestine collect fat from digested food.

The greater and lesser splanchnic nerves provide sympathetic innervation to the jejunum and ileum.

The vagus nerve supplies parasympathetic innervation to the jejunum and ileum.

Autonomic innervation regulates the movements and secretions of the intestines, helping with digestion.

The intestine is sensitive to stretch, irritation, and changes in temperature.

The foregut includes the oesophagus, stomach, and proximal duodenum.

The midgut includes the distal duodenum, jejunum, ileum, cecum, appendix, and ascending colon.

The hindgut includes the transverse colon, descending colon, sigmoid colon, rectum, and anal canal.

Retroperitoneal organs are located behind the peritoneum, while peritoneal organs are covered by peritoneum.

Secondarily retroperitoneal organs were initially peritoneal but have become attached to the posterior abdominal wall.