Advanced Sigmoid Colon Quiz

Q1. What feature of the sigmoid mesocolon contributes to the mobility of the sigmoid colon?

• Absence of all vascular attachments
• A mesenteric attachment that suspends the bowel while permitting mobility
• Attachment to the diaphragm by the falciform ligament
• Complete fusion of the colon to the posterior wall

Q2. Why is the sigmoid colon particularly susceptible to volvulus compared with a fixed colonic segment?

• It lacks a blood supply
• Its mobility and mesenteric configuration can permit twisting around the mesenteric axis
• It is always retroperitoneal and immobile
• It is attached directly to the liver

Q3. Which important retroperitoneal structure is related to the root of the sigmoid mesocolon and must be considered during surgery?

• Right brachial artery
• Left ureter
• Common carotid artery
• Thoracic duct in the neck

Q4. Which vascular structure also lies near the root of the sigmoid mesocolon?

• Axillary vessels
• Left common iliac vessels
• Coronary arteries
• Subclavian vessels

Q5. Why can interruption of a sigmoid artery sometimes be compensated by adjacent arterial branches?

• The sigmoid colon has no need for arterial perfusion
• The portal vein directly supplies arterial blood
• The inferior vena cava replaces the artery
• Collateral anastomoses connect adjacent colic arterial territories

Q6. How does the embryologic origin of the sigmoid colon correspond to its arterial supply?

• Its hindgut origin corresponds to inferior mesenteric arterial supply
• Its embryologic origin has no relationship to regional arterial supply
• Its midgut origin corresponds to superior mesenteric supply
• Its foregut origin corresponds to celiac supply

Q7. Which statement best describes parasympathetic innervation of the sigmoid colon?

• The pudendal nerve provides parasympathetic fibers to the sigmoid wall
• The vagus nerve provides its exclusive parasympathetic supply
• Pelvic splanchnic fibers from S2 to S4 reach it through autonomic plexuses and synapse near or within the bowel wall
• Parasympathetic fibers synapse in the sympathetic trunk

Q8. Which pathway best describes lymphatic drainage from the sigmoid colon?

• Popliteal nodes to superior mesenteric nodes
• Superficial inguinal nodes directly to axillary nodes
• Celiac nodes directly to cervical nodes
• Epicolic and paracolic nodes to sigmoid intermediate nodes to inferior mesenteric nodes

Q9. What anatomical change helps identify the transition from sigmoid colon to rectum?

• The three taeniae broaden into a continuous longitudinal muscle layer
• Villi suddenly appear in the mucosa
• The bowel acquires a new mesoappendix
• The circular muscle disappears

Q10. Which statement best integrates the anatomy of the sigmoid colon?

• It is a foregut organ suspended by the lesser omentum
• It is a fixed midgut segment supplied only by the superior mesenteric artery
• It is an extraperitoneal organ without autonomic innervation
• It is a mobile intraperitoneal hindgut segment with sigmoid mesenteric, inferior mesenteric vascular, lymphatic, and pelvic autonomic relationships