Anatomy of the Small and Large Intestines

Vocabulary flashcards covering the anatomical features, dimensions, relations, and blood supply of the small and large intestines based on the lecture notes.

Duodenum

The shortest, widest, and most fixed part of the small intestine, measuring $25\,\text{cm}$ and curved around the head of the pancreas in a ‘C’ shape.

First part of the duodenum

A $5\,\text{cm}$ segment beginning at the pylorus, related anteriorly to the quadrate lobe of the liver and gallbladder, and superiorly to the epiploic foramen.

Major duodenal papilla

An elevation present posteromedially in the second part of the duodenum, $8$ to $10\,\text{cm}$ distal to the pylorus, where the hepatopancreatic ampulla opens.

Minor duodenal papilla

A site $6$ to $8\,\text{cm}$ distal to the pylorus where the accessory pancreatic duct opens into the second part of the duodenum.

Plica longitudinalis

A longitudinal fold located below the major duodenal papilla in the interior of the second part of the duodenum.

Third part of the duodenum

A $10\,\text{cm}$ horizontal segment that passes in front of the inferior vena cava and is crossed anteriorly by the superior mesenteric vessels and the root of the mesentery.

Ligament of Treitz

A fibromuscular band, also known as the suspensory muscle of the duodenum, which suspends and supports the duodenojejunal flexure.

Jejunum

The upper two-fifths of the mobile small intestine, characterized by thicker walls, wider lumen, longer vasa recta, and $1$ or $2$ arterial arcades.

Ileum

The lower three-fifths of the mobile small intestine, characterized by thinner walls, shorter vasa recta, and the presence of Peyer's patches.

Supraduodenal artery of Wilkie

An artery supplying the first part of the duodenum, which is usually a branch of the common hepatic artery.

Caecum

A large blind sac $6\,\text{cm}$ long and $7.5\,\text{cm}$ broad situated in the right iliac fossa that forms the commencement of the large intestine.

Ileocaecal valve

A structure consisting of two lips and two frenula that prevents reflux from the caecum to the ileum and is actively closed by sympathetic nerves.

Vermiform appendix

A worm-like diverticulum arising from the posteromedial wall of the caecum, about $2\,\text{cm}$ below the ileocaecal orifice.

Retrocolic position

The most common position of the appendix, occurring in about $65\%$ of cases, where it lies behind the caecum or colon.

McBurney’s point

The site of maximum tenderness in appendicitis, located at the junction of the lateral one-third and medial two-thirds of the line joining the right anterior superior iliac spine to the umbilicus.

Valve of Gerlach

An indistinct semilunar fold of mucous membrane that occasionally guards the appendicular orifice.

Mesoappendix

A small, triangular fold of peritoneum that suspends the appendix and contains the appendicular artery.

Right colic flexure

Also called the hepatic flexure, it is the junction of the ascending and transverse colon located on the lower part of the right kidney.

Left colic flexure

Also called the splenic flexure, it is the junction of the transverse and descending colon located at the level of the $T12$ vertebra and attached to the eleventh rib by the phrenicocolic ligament.

Phrenicocolic ligament

A horizontal fold of peritoneum that attaches the left colic flexure to the eleventh rib and supports the spleen.

Sigmoid colon

A sinuous loop approximately $37.5\,\text{cm}$ long that extends from the pelvic brim to the third piece of the sacrum.