2. Anatomy
• Anatomy
1. Cecum
2. Ileum
3. Vermiform appendix
The appendix is situated in the right lower quadrant of the abdomen in a region commonly called the right iliac fossa. The appendicular ostium is normally situated in the middle of a line joining the anterior and superior iliac spine to the umbilicus (McBurney’s point). In this position, the tip of the appendix extends to the junction of the right and middle thirds of a line joining both anterior and superior iliac spines.
The serosal junction of the appendix is found at the internal part of the cecal fundus where it joins the free tenia.
The ileocolic artery is a branch of the superior mesenteric artery. It divides into the:
1. Ileocolic artery
2. Posterior cecal artery
3. Anterior cecal artery
4. Appendicular artery
The ileocecal lymphatics are situated along the anterior and posterior cecal arteries. They are drained by a large lymph node chain situated in the ileocecal flexure.
1. Mesentery
2. Superior ileocecal recess
3. Inferior ileocecal recess
4. Mesoappendix
The cecal mesenteric fold demarcates the anterior or superior ileocecal recess. The ileoappendicular peritoneal fold, along with the mesoappendix, demarcates the inferior or posterior ileocecal recess.
• Variations
The position of the appendix in the lesser pelvis in relation to its neighboring organs is variable. The following are common locations:
1. Retrocecal appendix
2. Mesoceliac appendix
3. Normal appendix
4. Pelvic appendix
Variations in cecum position are as follows:
1. Right iliac fossa (classic position)
2. Pelvic cecum
3. Subhepatic cecum
4. Redundant cecum
In case of redundant cecum, the appendix comes up behind the ascending colon in a subhepatic position.
The usual anatomical landmarks (cecal teniae, antimesenteric part of the small intestine, ileocecal junction, etc) are altered by inflammation-induced changes and adhesions.
An adhesive phlegmon made up of intestinal loops and omentum can form a periappendicular mass.
Generalized peritonitis occurs when the entire peritoneal cavity becomes infected following the perforation of the appendix. Peritonitis is first identified by visualization of a periappendicular abscess or a purulent collection at the level of the right paracolic gutter and the rectouterine pouch (pouch of Douglas).
From the right paracolic gutter, the purulent liquid follows 2 paths:
- it flows towards the pelvis, crosses to the left in front of the sigmoid colon, and spreads to the left gutter and left subphrenic region,
- it flows up the right gutter towards the right subphrenic and subhepatic regions. |