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Appendix
• Appendix is a Latin word from appendere. • It means to hang upon. • It is a blind-ended muscular tube attached to the posteromedial wall of cecum, near the junction of ileum with cecum.
• It is actually a part of cecum where the three taeniae coli merge to form outer longitudinal muscle layer.
• It is an out pouching or pocketing from cecum.
Teniae coli
• The teniae coli (also taeniae coli) are three separate longitudinal ribbons of smooth muscles on the outside of the ascending, transverse, descending and sigmoid colons.
• They are visible, and can be seen just below the serosa or fibrosa.
• They are • the Mesocolic, • Libera or Free and • The Omentalis• The teniae coli contract lengthwise to produce the haustrations, the bulges in the colon.
• The teniae coli contract lengthwise to produce the haustrations, the bulges in the colon.
• The bands converge at the root of the appendix.
• At the recto-sigmoid junction, the taeniae spread out and unite to form longitudinal muscle layer.
• These bands correspond to the outer layer of the muscularis externa, in other portions of digestive tract.
• The appendix is 9 cm (7 to 11cm) in length but can range from 2 to 20 cm. The diameter of the appendix is 1 to 7 mm.
• It is relatively longer in children and decreases after 40 years of age.
• Following statements regarding appendix are true EXCEPT
• It is a blind-ended muscular tube attached to the anteromedial wall of cecum, near the junction of ileum with cecum.
• The appendix is located in the right lower quadrant of abdomen (right iliac fossa).
• The mesoappendix extends the whole length of appendix.
• Appendicular artery runs at the margin of mesoappendix.
• Lymph drainage of appendix is to ileocolic lymph nodes.
• Following statements regarding appendix are true EXCEPT
• It is a blind-ended muscular tube attached to the anteromedial wall of cecum, near the junction of ileum with cecum. C
• The appendix is located in the right lower quadrant of abdomen (right iliac fossa).
• The mesoappendix extends the whole length of appendix.
• Appendicular artery runs at the margin of mesoappendix.
• Lymph drainage of appendix is to ileocolic lymph nodes.
• Appendix is a blind-ended muscular tube attached to the posteromedial wall of cecum, near the junction of ileum with cecum.
McBurney’s point
• The appendix is located in the right lower quadrant of abdomen (right iliac fossa).
• Its position within the abdomen corresponds to a point on the surface known as McBurney’s point.
• For appendicular base draw a line from anterior superior iliac supine to the umbilicus.
• The appendicular base is at the junction of the lateral and middle third of this line.
• This is McBurney’s point.
• While the base of the appendix is at a fairly constant location, 2 cm below the ileocecal valve, the location of the tip of the appendix can vary from being retrocecal (behind the cecum) to being in the pelvis.
• In rare individuals with situs inversus, the appendix may be located on left side, in the lower left iliac fossa.
• One of the followings is the least common position of appendix
• Retro-cecal. Appendix is posterior to cecum and lower part of ascending colon.
• Pelvic. Appendix is descending downward over the pelvic brim.
• Sub-cecal. The appendix is descending down below the cecum.
• Pre-ileal. Here the appendix is related to the anterior abdominal wall. It is anterior to the terminal part of ileum.
• Post-ileal or retro-ileal. Here the appendix is posterior to the terminal part of ileum.
• One of the followings is the least common position of appendix
• Retro-cecal. Appendix is posterior to cecum and lower part of ascending colon.
• Pelvic. Appendix is descending downward over the pelvic brim.
• Sub-cecal. The appendix is descending down below the cecum.
• Pre-ileal. Here the appendix is related to the anterior abdominal wall. It is anterior to the terminal part of ileum.
• Post-ileal or retro-ileal. Here the appendix is posterior to the terminal part of ileum. C
• Retro-cecal (70%). Appendix is posterior to cecum and lower part of ascending colon.
• Para-cecal or para-colic. Appendix runs along the lower border of cecum and if long enough, ascends along ascending colon.
• Pre-cecal. Appendix is anterior to cecum and lower part of colon.
• Sub-cecal. The appendix is descending down below the cecum.
• Pelvic (20%). Appendix is descending downward over the pelvic brim. It is closely related to right fallopian tube and ovary.
• Promontoric . The appendix runs medially (left-ward) and horizontally, inferior and parallel to ileum from cecum to the promontory of sacrum.
• Pre-ileal. Here the appendix is related to the anterior abdominal wall. It is anterior to the terminal part of ileum.
• Post-ileal or retro-ileal (0.2%). Here the appendix is posterior to the terminal part of ileum.
• The mesoappendix (mesentery of appendix) is short, triangular and variable.
• It extends the whole length of appendix. • It is connected to the inferior ileal mesentery.
• Inferior ileocecal recess• It is a recess inferior to the terminal ileum and opens infero-medially (down and left)
• It is formed by ileocecal fold, which extends from terminal ileum to mesoappendix.
• The fold and recess can be used to trace the base of the appendix.
• The boundaries of inferior ileocecal recess are• Above: terminal ileum • Front: ileocecal fold• Behind: mesoappendix• Right: cecum
• Ileocecal recess• Latin: Plica ileocaecalis
Ileocolic artery
• The ileocolic artery is the lowest branch arising from the concavity of superior mesenteric artery.
• It passes downward and to the right behind the peritoneum toward the right iliac fossa, where it divides into a superior and an inferior branch
• The superior branch anastomoses with right colic artery.
• The inferior branch anastomoses with the end of superior mesenteric artery
• Supplies the cecum, ileum, and appendix.
Branches
• Colic artery to ascending colon• Anterior and posterior cecal arteries to cecum• Ileal artery to terminal ileum• Appendicular artery to appendix
• Appendicular artery runs at the margin of mesoappendix. It is a branch of the inferior division of ileocolic artery which is a branch of superior mesenteric artery.
• The appendicular artery runs behind the terminal ileum to enter the mesoappendix. Here it gives a recurrent branch which anastomoses at the base of the appendix with a branch of posterior cecal artery.
• The posterior cecal artery is also a branch of inferior division of ileocolic artery.
• The terminal part of appendicular artery lies on the wall of the appendix and may be thrombosed in appendicitis, resulting in distal gangrene or necrosis.
• Appendicular vein drains into ileocolic vein which is a tributary of superior mesenteric vein.
• Superior mesenteric vein drains into portal vein.
McBurney’s point
• The junction of the lateral and middle thirds of the line that joins the right anterior superior iliac spine to the umbilicus is used as a surface marking for the base of the appendix.
• The three teniae coli converge at the tip of the cecum to form the continuous longitudinal muscle layer of the appendix.
• The base of the appendix can be located by tracing the anterior taenia coli (taenia libera) to the tip of the cecum.
• The ileocecal fold of peritoneum, which connects the terminal 2.5 cm of ileum to the cecum, can also be used to locate the base of the appendix.
• Ileocecal fold forms the anterior boundary of inferior ileocecal recess. This fold is also called “bloodless fold of Treves”
• A short, triangular mesoappendix extends along the length of the appendix and connects it to the lower portion of the mesentery of the ileum.
McBurney’s point isA. at the junction of lateral two-third and medial on-third of the
line that joins the right anterior superior iliac supine to the umbilicus
B. at the junction of the lateral one-third and medial two-third of the line that joins the right anterior inferior iliac supine to the umbilicus
C. at the junction of medial and middle third of the line that joins the right anterior superior iliac supine to the umbilicus
D. at the junction of the lateral one-third and medial two-third of the line that joins the right anterior superior iliac supine to the umbilicus
E. at the junction of the lateral one-third and medial two-third of the line that joins the left anterior superior iliac supine to the umbilicus
McBurney’s point isA. at the junction of lateral two-third and medial on-third of the
line that joins the right anterior superior iliac supine to the umbilicus
B. at the junction of the lateral one-third and medial two-third of the line that joins the right anterior inferior iliac supine to the umbilicus
C. at the junction of medial and middle third of the line that joins the right anterior superior iliac supine to the umbilicus
D. at the junction of the lateral one-third and medial two-third of the line that joins the right anterior superior iliac supine to the umbilicus C
E. at the junction of the lateral one-third and medial two-third of the line that joins the left anterior superior iliac supine to the umbilicus
• Deep tenderness at McBurney's point, known as McBurney's sign, is a sign of acute appendicitis.
Identification points
• Lining epithelium is simple columnar with numerous goblet cells
• Crypts of Lieberkun or intestinal glands are numerous but not closely packed. They are lined by simple columnar epithelium with lot of goblet cells.
•
• Lamina propria contains large amounts of lymphoid tissue, extending through muscularis mucosae into submucosa.
• Lymphoid nodules surround the lumen completely.
• Muscular layer consist of inner circular and outer longitudinal layer.
• Out longitudinal muscle layer is a continuous layer and not arranged in three bands or teniae coli.
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