Viscera (heart, lungs, liver, gastrointestinal tract)
Sigmoid colon
Colon sigmoideum
- Origin
- Begins at the pelvic brim in the left iliac fossa
- Insertion
- Forms an S-shaped mobile loop suspended by the sigmoid mesocolon, ending at S3 to become the rectum
- Function
- Stores fecal matter prior to defecation and propels it into the rectum via mass movements
- Innervation
- Inferior mesenteric and inferior hypogastric plexuses (parasympathetic pelvic splanchnic S2-S4, sympathetic L1-L2)
- Movement & chain
- Powerful contractile propulsion triggered by the gastrocolic reflex
- Palpation
- Palpable in the left lower quadrant, especially when filled with stool
- Clinical
- Acute sigmoid diverticulitis ('left-sided appendicitis' with LLQ pain, fever, leukocytosis), sigmoid volvulus (classic 'coffee bean sign' on abdominal radiograph), colorectal cancer.
- Segmental innervation
- S2-S4 and L1-L2 levels
- In clinical practice
- Assessment of left lower quadrant rebound tenderness, managing post-Hartmann colostomy or sigmoid resection, bowel regimen counseling
- Region in the model
- Viscera (heart, lungs, liver, gastrointestinal tract)