🥇 Anatomía del DUODENO. Fácil, Rápida y Sencilla

Anatomy of the Duodenum

Introduction to the Duodenum

• The video introduces the anatomy of the duodenum, which is the first portion of the small intestine and a continuation from the pyloric portion of the stomach.

• It emphasizes that everything following the pyloric sphincter is part of the small intestine, specifically starting with the duodenum.

Structure and Function

• The duodenum receives chyme from the stomach and connects to the jejunum at the duodenal-jejunal junction (Treitz angle).

• The term "duodenum" derives from its length, approximately 12 inches or 25 to 30 centimeters, indicating it is relatively short compared to other intestinal sections.

Portions of the Duodenum

• The duodenum consists of four portions:

• First (superior)

• Second (descending)

• Third (inferior)

• Fourth (ascending)

• Notably, three out of these four portions are retroperitoneal, meaning they are fixed in place behind peritoneum; only the first portion is intraperitoneal and more mobile.

Detailed Examination of Portions

Superior Portion

• The superior portion is also known as:

• Duodenal bulb portion

• Infrahepatic portion

• This section lacks semicircular folds initially but has them along its length. These folds are referred to as Kerckring folds.

Anatomical Relationships

• The upper part runs left to right and has significant relationships with surrounding structures such as:

• Pancreas posteriorly

• Portal vein and common bile duct also located posteriorly.

Descending Portion

• Known as prerenal due to its position in front of the right kidney. It has important anatomical relationships including:

• Posterior relationship with renal structures like renal pelvis, artery, and vein.

Anatomy of the Duodenum and Its Relationships

Overview of the Duodenum's Structure

• The parietal peritoneum covers the duodenum, contrasting with the visceral peritoneum covering other portions. This distinction is crucial for understanding anatomical relationships.

• The second portion of the duodenum connects to the pancreas, forming a narrow relationship that complicates dissection in cadavers due to their close proximity.

Transition Between Portions of the Duodenum

• The third portion, also known as inferior, transverse, or horizontal duodenum, runs from right to left and has significant anatomical relationships with surrounding structures like the ureter and major blood vessels.

• As it transitions into the fourth portion (ascending), it maintains close relations with both the head of the pancreas and major vascular structures such as superior mesenteric vessels.

Anatomical Junctions and Musculature

• The junction between the third and fourth portions forms an acute angle known as the duodeno-jejunal angle, which is supported by Treitz muscle (or suspensory muscle of duodenum).

• Treitz muscle plays a vital role in maintaining proper positioning between these sections of the digestive tract.

Ligaments and Fixed Positioning

• The hepatoduodenal ligament connects from liver to first portion of duodenum at L2 vertebra level; this fixed position contrasts with more mobile organs like stomach.

• The duodenum's attachment to posterior abdominal wall emphasizes its stability compared to other parts of gastrointestinal tract.

Ductal Systems Feeding into Duodenum

• The common bile duct and main pancreatic duct empty into second portion; accessory pancreatic duct drains separately into this section aiding digestion.

• At their junction within second portion lies ampulla of Vater (hepato-pancreatic ampulla), where both ducts converge before entering duodenum.

Papillae in Duodenal Anatomy

• Major duodenal papilla receives drainage from common bile duct and main pancreatic duct; referred to as greater caruncle in some texts.

Understanding the Sphincters and Blood Supply of the Duodenum

The Sphincters Associated with the Duodenum

• The major duodenal papilla features a series of sphincters that regulate the opening and closing of ducts, including the common bile duct sphincter.

• The sphincter of Oddi is located at the distal end of the common bile duct, while the pancreatic duct has its own sphincter.

• A third sphincter, known as the sphincter of ampulla of Vater or hepato-pancreatic sphincter, is found in the ampulla of Vater where these ducts empty into the duodenum.

• Visual representation shows distinct muscular structures for each sphincter: Oddi, pancreatic duct, and ampulla of Vater.

Blood Supply to the Duodenum

• The primary blood supply to the duodenum comes from the gastroduodenal artery, which branches into four arteries including supraduodenal and retroduodenal arteries.

• Two superior and two inferior pancreatoduodenal arteries arise from this artery; they are crucial for supplying both head of pancreas and duodenum.

• These pancreatoduodenal arteries form anastomoses with inferior pancreatoduodenal arteries from superior mesenteric artery creating anterior and posterior arches for better blood flow.

Venous Drainage and Innervation

• Venous drainage involves pancreatic-duodenal veins that connect to both superior mesenteric vein and portal vein; key veins include anterior and posterior pancreato-duodenal veins.

• The pre-pyloric vein is significant as it connects stomach to duodenum.