Advanced Sigmoid Colon Quiz

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

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

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

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

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

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

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

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

• The portal vein directly supplies arterial blood
• The sigmoid colon has no need for arterial perfusion
• 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 midgut origin corresponds to superior mesenteric supply
• Its embryologic origin has no relationship to regional arterial supply
• Its hindgut origin corresponds to inferior mesenteric arterial supply
• Its foregut origin corresponds to celiac supply

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

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

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?

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

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

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