Applied Anatomy of Abdomen

1. Applied Anatomy of Abdomen Abdomen, Pelvis & Perineum Unit Lecture 10 د. حيدر جليل الأعسم

2. Lecture 1: Anterior Abdominal wall Surgical Incisions • Along lines of cleavage? Location depends on: type of operation, location of organ(s), bony or cartilaginous boundaries, avoidance of (especially motor) nerves, maintenance of blood supply, and minimizing injury to muscles & fascia. A. Longitudinal Incisions: 1. Median or midline incision: through lineaalba above/below umbilicus 2. Paramedian incisions: longitudinal incisions para-sagittal plane. 3. Pararectus incisions:along lateral border of rectus sheath. undesirable? 4. Abdominothoracicincisionfor lower end of esophagus. B. Oblique and Transverse Incisions: 1. Gridiron (muscle-splitting) incisionsused for an appendectomy. McBurney incision is made at McBurney point? less popular? 2. Suprapubic(Pfannenstiel) incisions(bikini incisions) at pubic hairline for cesarean section and most gynecological and obstetrical operations. 3. Subcostal incisionsfor gallbladder & biliary ducts (right side) and for spleen (left side). It is parallel & inferior to costal margin? 4. Inguinal incisionsfor repairing hernias may injure ilioinguinalnerve.

3. Lecture 1: Anterior Abdominal wall Paracentesis of the Abdomen: It is withdrawal of excessive collections of peritoneal fluid, as in ascites. A needle or catheter is inserted through anterior abdominal wall. If a needle is inserted in the flank, it will pass through the following: • skin, • superficial fascia, • deep fascia, • aponeurosisof external oblique, • internal oblique muscle, • transversusabdominis muscle, • fascia transversalis, • extraperitonealfatty tissue • parietal peritoneum.

4. Lecture 1: Anterior Abdominal wall Collateral Pathways of Superficial Abdominal Veins When flow in inferior vena cava is obstructed, anastomoses between tributaries of superior & inferior vena cavae , such as thoracoepigastric vein, may provide collateral pathways by which obstruction may be bypassed, allowing blood to return to the heart. Small cutaneous (systemic) veins surrounding umbilicus also anastomose with the paraumbilical veins (tributaries of portal vein), which run with obliterated umbilical vein (round ligament of liver). During either caval or portal obstruction, anastomosing veins may also become distended, causing caput medusae appearance.

5. Lecture 2: Inguinal Canal & Scrotum Varicocele A varicocele is a condition in which the veins of the pampiniform plexus are elongated and dilated. It is a common disorder in adolescents and young adults, with most occurring on the left side. This is thought to be because the right testicular vein joins the low-pressure inferior vena cava, whereas the left vein joins the left renal vein, in which the venous pressure is higher.

6. Lecture 3: Posterior Abdominal Wall Psoas Abscess and Tuberculosis Psoas fascia covers anterior surface of psoas muscle and can influence direction taken by a tuberculous abscess. TB of thoracolumbar vertebrae results in destruction of vertebral bodies, with possible extension of pus laterally under psoas fascia. From there, pus tracks downward, following course of psoas muscle, and appears as a swelling in upper part of thigh below inguinal ligament. It may be mistaken for a femoral hernia.

7. Lecture 5: Esophagus, Stomach & Duodenum Hiatus Hernia A hiatus hernia is a protrusion of a part of stomach into mediastinum through esophageal hiatus of diaphragm. Hernias occur most often in people after middle age, possibly because of weakening of muscular part of diaphragm and widening of esophageal hiatus. Two types are: Paraesophageal hiatal hernia: less common, cardia remains in its normal position. However, a part of fundus extends through esophageal hiatus anterior to the esophagus. Sliding hiatal hernia: abdominal part of esophagus, cardia, and parts of fundus of stomach slide superiorly through esophageal hiatus to thorax.

8. Lecture 5: Esophagus, Stomach & Duodenum Vagotomy: It is surgical section of the vagus nerves because secretion of acid is largely controlled by vagus nerves. A. Truncal vagotomy:(surgical section of vagal trunks) is rarely performed because innervation of other abdominal structures is also sacrificed. B. Selective gastric vagotomy:stomach is denervated but vagal branches to pylorus, liver & biliary ducts, intestines & celiac plexus are preserved. C. Highly selective vagotomy: attempts to denervate only area in which parietal cells are located, sparing other gastric function (motility) stimulated by vagus nerve.

9. Lecture 6: Small & Large Intestine Visceral Referred Pain: There are two types of pain: A. Somatic pain(sharp and localized easily) arises from organs such as muscles, bones & parietal peritoneum. B. Visceral pain(dull and poorly localized) arises from an organ such as stomach and intestine. C. Referred pain (dull and localized) is a visceral pain arising from viscera but felt (radiate) to dermatome level, which receives visceral fibers from organ concerned.

10. Lecture 6: Small & Large Intestine Appendicitis Is acute inflammation of the appendix is caused by occlusion of lumen either in young people by hyperplasia of lymphatic follicles in appendix Or in older people, obstruction results from a fecolith that forms around a center of fecal matter. When secretions from appendix cannot escape, appendix swells, stretching visceral peritoneum. Visceral pain of appendicitis, therefore, referred to periumbilical region because afferent pain fibers enter spinal cord at T10 level. Later, severe pain in right lower quadrant results from irritation of parietal peritoneum lining abdominal wall (Shifting Pain).

11. Lecture 8: Liver, Spleen and Pancreas Gallstones A gallstone is a concretion composed chiefly of cholesterol crystals in biliary system. They may cause injury to gallbladder or obstruction of biliary tract. Distal end of hepatopancreatic ampullais narrowest part of biliary passages and is a common site for impaction of gallstones. Hartmann pouch (infundibulum of gallbladder) is a dilation at junction of neck of gallbladder and cystic duct and is another common site for impaction. Gallstones lodged in cystic duct causes biliary colic (intense, spasmodic pain). If stone blocks cystic duct, cholecystitis(inflammation of gallbladder) occurs because of bile accumulation & enlargement of gallbladder. Acute Cholecystitisis inflammation of gallbladder which may cause irritation of subdiaphragmatic parietal peritoneum, which is supplied in part by phrenic nerve. This may give rise to referred pain over right shoulder.

12. Lecture 8: Liver, Spleen and Pancreas Gallstones in the Duodenum Dilated and inflamed gall bladder owing to an impacted gallstone in its duct, may develop adhesions with adjacent viscera. Continued inflammation may break down (ulcerate) tissue boundaries between gallbladder and a part of alimentary tract adherent to it, resulting in a cholecystenteric fistula. Because of their proximity to gallbladder, the superior part of duodenum and transverse colon are most likely to develop a fistula of this type. The fistula would enable a large gallstone, incapable of passing though the cystic duct, to enter the alimentary tract that may become trapped at the ileocecal valve, producing a bowel obstruction (gallstone ileus).

13. Lecture 8: Liver, Spleen and Pancreas Pancreatic Head Cancer Cancer of the head often compresses and obstructs the bile duct and/or the hepatopancreatic ampulla. This condition causes obstruction, resulting in the retention of bile pigments, enlargement of the gallbladder, and jaundice (obstructive jaundice). Cancer of the neck and body of the pancreas may cause portal or inferior vena caval obstruction because the pancreas overlies these large veins.

14. Lecture 9: Kidney & Ureter Renal and Ureteric Calculi Calculi may form and become located in calices of kidneys, ureters, or urinary bladder. A renal calculus (kidney stone) may pass from kidney into renal pelvis and then into ureter. If stone is sharp, or it is larger than normal lumen of ureter (about 3 mm) causing excessive distension of this muscular tube, ureteric calculus will cause severe intermittent pain (ureteric colic) as it is gradually forced down the ureter by waves of contraction. Calculus may cause complete or intermittent obstruction of urinary flow. Depending on level of obstruction, pain may be referred to the lumbar or inguinal regions, or the external genitalia and/or testis.

15. Lecture 9: Kidney & Ureter Pelvic Kidney (ectopic kidney) Kidney may be arrested in some part of its normal embryonic ascent; it usually is found at the brim of pelvis. Horseshoe Kidney Caudal ends of both kidneys fuse as they develop resulting in horseshoe kidney. Both kidneys start to ascend from pelvis, but the interconnecting bridge becomes trapped behind inferior mesenteric artery, so kidneys come to rest in low lumbar region. Both ureters are kinked as they pass inferiorly over the bridge of renal tissue, producing urinary stasis, which may result in infection and stone formation.

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