A 17-year-old girl is brought to the hospital due to abdominal pain, nausea, and vomiting. She began having periumbilical pain and nausea several hours ago and initially attributed her symptoms to some "bad food" she ate at a potluck lunch earlier in the day. However, her pain progressively worsened and became localized to the right lower quadrant. Temperature is 101 F (38.3 C), blood pressure is 124/78 mm Hg, pulse is 92/min, and respirations are 14/min. On examination, the patient has right lower quadrant tenderness with guarding. Laboratory evaluation shows leukocytosis. Surgical intervention is planned. During surgery, which of the following landmarks is most helpful in identifying the diseased organ?
Show Explanatory Sources
This patient most likely has appendicitis, which is usually treated by removing the appendix. During the procedure, the teniae coli can be used as a surgical landmark.
The teniae coli begin as a continuous layer of longitudinal muscle that surrounds the rectum just below the serosa. At the rectosigmoid junction, this layer condenses to form 3 distinct longitudinal bands that travel on the outside of the entire colon before converging at the root of the vermiform appendix. The teniae coli have a similar function as the outer layer of the muscularis externa in other portions of the digestive tract. If the appendix cannot be identified by palpation during an appendectomy, it can be located by following the teniae coli to its origin at the cecal base.
(Choices A and C) The greater omentum extends from the greater curvature of the stomach in front of the small intestine. It then reflects on itself and ascends to encompass the transverse colon before reaching the posterior abdominal wall. The lesser omentum extends from the fissure of ligamentum venosum and porta hepatis to the lesser curvature of the stomach (hepatogastric ligament) and the start of the duodenum (hepatoduodenal ligament).
(Choice B) The teniae coli run the length of the colon and contract lengthwise to form haustra, colonic sacculations causing the colon's segmented appearance. Compared to the circumferential small intestinal folds, the distance between haustra is wider and they do not span the entire colonic circumference. These differences help distinguish the colon from the small intestine on abdominal x-ray.
(Choice D) Acute appendicitis due to a retrocecal appendix can irritate the iliopsoas group of hip flexors. Psoas sign is abdominal pain elicited by passive thigh extension, which causes friction against nearby inflamed tissues. However, psoas sign can be due to any retroperitoneal irritation and is not specific for appendicitis.
Educational objective:
The teniae coli are 3 separate smooth muscle ribbons that travel longitudinally on the outside of the colon and converge at the root of the vermiform appendix. If the appendix cannot be identified by palpation during an appendectomy, it can be located by following the teniae coli to their origin at the cecal base.