Anatomy: Abdominopelvic. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form. Check for errors and try again. Thank you for updating your details. Log In. Sign Up. Become a Gold Supporter and see no ads. Log in Sign up. Articles Cases Courses Quiz. About Recent Edits Go ad-free.
Edit article. View revision history Report problem with Article. Citation, DOI and article data. Wijayagoonawardana, P. The skin and muscles of the abdominal wall receive their innervation by the anterior and lateral cutaneous branches of the thoracoabdominal nerves T7-T11 , the subcostal nerve T12 , the iliohypogastric nerve L1, sensation to the suprapubic region , and the ilioinguinal nerve L1, sensation to the ipsilateral medial thigh and scrotum.
Viscerally, the vagus nerve serves to parasympathetically innervate the vast majority of the gastrointestinal tract to include the foregut and midgut. The hindgut receives parasympathetic input from the sacral roots S2, S3, and S4. It is important to note that the visceral peritoneum and the underlying organs are insensitive to touch, temperature, or laceration, but rather perceive pain through stretch and chemical receptors.
Due to the innervation of the organs, pain is poorly localized and refers to the dermatomes of the spinal ganglia that provide the sensory fibers. Consequently, foregut pain is usually referred to the epigastrium, midgut to the umbilicus, and hindgut to the pubic region. The abdominal muscles assist in the process of respiration, protect the inner organs, provide postural support, and serve to flex, extend, and rotate the trunk of the body.
The four main abdominal muscle groups, from innermost to outermost, can be remembered by the mnemonic TIRE: Transversus abdominis, internal oblique, rectus abdominis, and external oblique. An easy way to remember which way the fibers run is to think of putting your hands in your pockets. The hand position represents the direction of the external obliques, and the internal obliques run perpendicular to this.
A midline raphe, the linea alba, is formed from the interweaving of the aponeuroses of the external oblique, internal oblique, and transversus abdominis.
The aponeurosis of the internal oblique muscle splits to encapsulate the rectus abdominis muscles above the arcuate line, however, below the arcuate line, both the aponeurosis of the internal oblique and the transversus abdominis are anterior to the rectus abdominis.
Various birth defects of the abdominal anatomy can occur. Examples include but are not limited to gastroschisis, omphalocele, congenital umbilical hernia, intestinal atresia, hypertrophic pyloric stenosis, annular pancreas, Hirschsprung disease, malrotation, agenesis, etc.
Clinically, the abdomen is roughly divided into nine regions by two sagittal planes from the midclavicular lines to the mid inguinal lines, and two transverse planes, one at the subcostal line and one at the iliac tubercles. The umbilicus serves at the center of the nine regions. Each region and its associated organs are detailed below:.
Surgically, the portal triad within the hepatoduodenal ligament is of considerable significance and includes the proper hepatic artery, common bile duct, and portal vein. The Pringle maneuver is when pressure is applied to this ligament to control hemorrhage. Abdominal signs and symptoms can be from a wide variety of disease processes to include vascular, infectious, trauma, autoimmune, musculoskeletal, idiopathic, neoplastic, congenital, etc.
The details below are not meant to serve as an exhaustive list; however, it should serve as a guide for commonly encountered pathology within their respective quadrants and can help guide clinical decision making, especially with regards to imaging and surgery. Commonly due to gastric reflux, gallbladder disease, hepatitis, peptic ulcer disease, pancreatitis, pyelonephritis, kidney stone, retrocecal appendicitis, or bowel obstructions. Commonly due to appendicitis, Crohn disease, cecal diverticulitis, ectopic pregnancy, endometriosis, inguinal hernia, ischemic colitis, ovarian cyst, ovarian torsion, pelvic inflammatory disease, psoas abscess, testicular torsion, or kidney stones.
Commonly due to gastric reflux, peptic ulcer disease, pancreatitis, splenic infarction or rupture, pyelonephritis, bowel obstruction, or aortic dissection. Commonly due to diverticulitis, kidney stones, pyelonephritis, ectopic pregnancy, inflammatory bowel disease, inguinal hernia, ovarian cysts, ovarian torsion, pelvic inflammatory disease, psoas abscess, testicular torsion, abdominal aortic aneurysm, irritable bowel syndrome, or small bowel obstructions.
The pectinate dentate line also serves as clinical significance. Above the pectinate line, one can expect internal hemorrhoids and adenocarcinoma.
The internal hemorrhoids are not painful due to their visceral innervation. Below the pectinate line, one can expect external hemorrhoids, anal fissures, and squamous cell carcinoma. Organs found in the right lower quadrant include the appendix, the upper portion of the colon, and the right ovary and the Fallopian tube in women.
The right lower quadrant may be assessed when diagnosing appendicitis, in which case, this quadrant would be tender and painful. Appendicitis Appendicitis is a condition in which the appendix becomes inflamed and filled with pus, causing pain.
If left untreated, appendicitis may cause your appendix to rupture and cause infection, which can be serious and even fatal. Organs in the left upper quadrant include the stomach, spleen, left portion of the liver, main body of the pancreas, the left portion of the kidney, adrenal glands, splenix flexure of the colon, and bottom part of the colon. This quadrant may feel tender in cases of appendicitis and abnormalities of the intestines, such as malrotation.
Organs found in this quadrant include the sigmoid colon, and the left ovary and Fallopian tube in women. Pain in this quadrant may be symptomatic of colitis, diverticulitis, or kidney stones.
Ovarian cysts in women or pelvic inflammation may also be at the root of pain in this quadrant. Diverticulitis Diverticula are small, bulging pouches that can form in the lining of your digestive system. Sometimes, however, one or more of the pouches become inflamed or infected. That condition is known as diverticulitis. Ureteral Colic This is most commonly caused by the obstruction of the urinary tract by kidney stones. Colitis Colitis, simply put, is inflammation of the colon.
The three most common forms of colitis are: ulcerative colitis, Crohn's disease, and infection. Ulcerative Colitis This is a chronic IBD that causes sores ulcers in the lining of your colon, as well as inflammation. Crohn's Disease This is a chronic inflammatory bowel disease that affects the lining of the digestive tract.
Inflammation can appear anywhere in the digestive tract, from the mouth to the anus, and it generally affects all the layers of the bowel walls, not just the inner lining.
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