Abdominal Radiographic Anatomy PDF

Chapter 3: Abdomen RADIOGRAPHIC ANATOMY By: Jacquiline M. Gealon, RRT  Abdominal Radiography The most common image is an anteroposterior (AP) supine abdomen, also sometimes called a KUB (kidneys, ureters, and bladder). These radiographs are taken without th...

Chapter 3: Abdomen RADIOGRAPHIC ANATOMY By: Jacquiline M. Gealon, RRT  Abdominal Radiography The most common image is an anteroposterior (AP) supine abdomen, also sometimes called a KUB (kidneys, ureters, and bladder). These radiographs are taken without the use of contrast media. Plain radiographs of the abdomen (KUB) commonly are taken before abdominal examinations are performed with the use of contrast media to rule out certain pathologies. Acute abdominal series Abdominal Radiography Certain acute or emergency conditions of the abdomen may develop from conditions such as bowel obstruction, perforations involving free intraperitoneal air (air outside the digestive tract), excessive fluid in the abdomen, or a possible intra-abdominal mass. These acute or emergency conditions require what is commonly called an “acute abdominal series,” or a “two-way” or “three-way abdomen” series, wherein several abdominal radiographs are taken in different positions to demonstrate air-fluid levels or free air or both within the abdominal cavity. ABDOMINAL MUSCLES Abdominal Radiography Many muscles are associated with the abdominopelvic cavity. The three that are most important in abdominal radiography are the diaphragm and the right and left psoas (so′-es) major. The diaphragm is an umbrella-shaped muscle that separates the abdominal cavity from the thoracic cavity. The two psoas major muscles are located on either side of the lumbar vertebral column.  Abdominal Organ Systems DIGESTIVE SYSTEM The digestive system, along with its accessory organs, the liver, gallbladder, and pancreas, fills much of the abdominal cavity. The spleen (part of the lymphatic system) is also partially visible in the left upper abdomen posterior to the stomach. The six organs of the digestive system are as follows: 1. Oral cavity 2. Pharynx 3. Esophagus 4. Stomach 5. Small intestine 6. Large intestine  Abdominal Organ Systems Oral Cavity, Pharynx, and Esophagus The oral cavity (mouth) and the pharynx (oropharynx and laryngopharynx) are common to the respiratory system and the digestive system The esophagus is located in the mediastinum of the thoracic cavity.  Abdominal Organ Systems Stomach and Small and Large Intestines The three digestive organs within the abdominal cavity are the stomach and small and large intestines. Stomach The stomach is the first organ of the digestive system that is located within the abdominal cavity. The stomach is an expandable reservoir for swallowed food and fluids. ⚬ Gastro is a common combining form denoting a relationship to the stomach ⚬ The term gastrointestinal (GI) tract or system describes the entire digestive system, starting with the stomach and continuing through the small and large intestines.  Abdominal Organ Systems Stomach and Small and Large Intestines Small intestine The small intestine continues from the stomach as a long, tubelike convoluted structure about 4.5 to 5.5 m (15 to 18 feet) in length. The three parts of the small intestine as follows: duodenum; jejunum; ileum. ⚬ Duodenum (A) The first portion of the small intestine, the duodenum, is the shortest but widest in diameter of the three segments. It is about 25 cm (10 inches) in length. When filled with contrast medium, the duodenum looks like the letter C. The proximal portion of the duodenum is called the duodenal bulb, or cap.  Abdominal Organ Systems Stomach and Small and Large Intestines ⚬ Jejunum and ileum (B and C) The remainder of the small bowel lies in the central and lower abdomen. The first two-fifths following the duodenum is called the jejunum, and the distal three-fifths is called the ileum. The orifice (valve) between the distal ileum and the cecum portion of the large intestine is the ileocecal valve.  Abdominal Organ Systems Radiograph of stomach and small intestine Air seldom is seen filling the entire stomach or small intestine on a plain abdominal radiograph of a healthy, ambulatory adult.  Abdominal Organ Systems Stomach and Small and Large Intestines Large intestine The sixth and last organ of digestion is the large intestine, which begins in the right lower quadrant at the junction with the small intestine at the ileocecal valve. The portion of the large intestine below the ileocecal valve is a saclike area called the cecum. The appendix (vermiform appendix) is attached to the posteromedial aspect of the cecum. The vertical portion of the large bowel above the cecum, the ascending colon, joins the transverse colon at the right colic flexure. The transverse colon joins the descending colon at the left colic flexure.  Abdominal Organ Systems Stomach and Small and Large Intestines Large intestine The descending colon continues as the S-shaped sigmoid colon in the lower left abdomen. The rectum ends at the anus, the sphincter muscle at the terminal opening of the large intestine.  Abdominal Organ Systems SPLEEN The spleen is the part of the lymphatic system that along with the heart and blood vessels is part of the circulatory system. It is an important abdominal organ that occupies a space posterior and to the left of the stomach in the left upper quadrant.  Abdominal Organ Systems ACCESSORY DIGESTIVE ORGANS Three accessory organs of digestion, also located in the abdominal cavity, are the (1) pancreas, (2) liver, and (3) gallbladder. Pancreas ⚬ The pancreas, which is not seen on a plain abdominal radiograph, is an elongated gland that is located posterior to the stomach and near the posterior abdominal wall, between the duodenum and the spleen. ⚬ The average length is about 12.5 cm (6 inches). Its head is nestled in the C-loop of the duodenum, and the body and tail of the pancreas extend toward the upper left abdomen.  Abdominal Organ Systems ACCESSORY DIGESTIVE ORGANS ⚬ This relationship of the duodenum and the head of the pancreas sometimes is referred to as “the romance of the abdomen.” ⚬ The pancreas is part of the endocrine (internal) secretion system and the exocrine (external) secretion system. Liver ⚬ The liver is the largest solid organ in the body, occupying most of the right upper quadrant. ⚬ The liver has numerous functions, one of which is the production of bile that assists in the digestion of fats.  Abdominal Organ Systems ACCESSORY DIGESTIVE ORGANS Gallbladder ⚬ The gallbladder is a pear-shaped sac located below the liver. ⚬ The primary functions of the gallbladder are to store and concentrate bile and to contract and release bile when stimulated by an appropriate hormone. ⚬ In most cases, the gallbladder cannot be visualized with conventional radiographic techniques without contrast media.  Abdominal CT CROSS-SECTIONAL IMAGES Organ Systems  Abdominal Organ Systems Urinary System The urinary system is another important abdominal system. The urinary system comprises the following: ⚬ Two kidneys ⚬ Two ureters ⚬ One urinary bladder ⚬ One urethra Each kidney drains via its own ureter to the single urinary bladder. The bladder, which is situated above and behind the symphysis pubis, stores urine. Under voluntary control, the stored urine passes to the exterior via the urethra. The two suprarenal (adrenal) glands of the endocrine system are located at the superomedial portion of each kidney.  Abdominal Organ Systems EXCRETORY OR INTRAVENOUS UROGRAM The kidneys usually are seen faintly on a plain abdominal radiograph because of a fatty capsule that surrounds each kidney The contrast medium examination, excretory or intravenous urogram (IVU), is a radiographic examination of the urinary system performed with intravenous contrast medium.  Abdominal Organ Systems Sectional Image A. Inferior lobe of liver B. Ascending colon C. Right kidney D. Right ureter E. Right psoas major F. L2-L3 vertebra G. Left kidney H. Left ureter I. Descending colon J. Loops of small intestines (jejunum) Two major blood vessels of the abdomen are also seen, labeled K and L. K is the large abdominal aorta, and L is the inferior vena cava.  Abdominal Cavity Four important terms that describe the anatomy of the abdominal cavity appear on the drawings to the right and are described subsequently. These four terms are: 1. Peritoneum 2. Mesentery 3. Omentum 4. Mesocolon  Abdominal Cavity Peritoneum Most of the abdominal structures and organs as well as the wall of the abdominal cavity in which they are contained are covered to varying degrees by a large serous, double-walled, saclike membrane called the peritoneum. Two types of peritoneum exist: parietal and visceral. The two-layered peritoneum that adheres to the cavity wall is called parietal peritoneum, whereas the portion that covers an organ is called visceral peritoneum. ⚬ The space or cavity between the parietal and visceral portions of the peritoneum is called the peritoneal cavity.  Abdominal Cavity Peritoneum ⚬ This cavity contains some serous lubricating-type fluid, which allows organs to move against each other without friction. An abnormal accumulation of this serous fluid is a condition called ascites. A layer of visceral peritoneum only partially covers certain organs that are more closely attached to the posterior abdominal wall At this level, the ascending and descending colon, the aorta, and the inferior vena cava are only partially covered; therefore, this lining would not be considered mesentery, and these structures and organs are called retroperitoneal  Abdominal Cavity Mesentery The peritoneum forms large folds that bind the abdominal organs to each other and to the walls of the abdomen One of these double folds that hold the small intestine in place is called mesentery. Mesentery is the double fold of peritoneum that extends anteriorly from the posterior abdominal wall to envelop completely a loop of small bowel Mesentery is the specific term for a double fold of peritoneum that loosely connects the small intestine to the posterior abdominal wall  Abdominal Cavity Omentum The term omentum refers to a specific type of double- fold peritoneum that extends from the stomach to another organ. The lesser omentum extends superiorly from the lesser curvature of the stomach to portions of the liver. The greater omentum connects the transverse colon to the greater curvature of the stomach inferiorly. The greater omentum drapes down over the small bowel then folds back on itself to form an apron along the anterior abdominal wall.  Abdominal Cavity Mesocolon The peritoneum that attaches the colon to the posterior abdominal wall is the mesocolon. Four forms of mesocolon exist, each named according to the portion of the colon to which it is attached: ascending, transverse, descending, and sigmoid or pelvic. The transverse mesocolon is shown as the visceral peritoneum that loosely connects the transverse colon to the posterior abdominal wall.  Abdominal Cavity Greater Sac and Lesser Sac The major portion of the peritoneal cavity is called the greater sac and is commonly referred to as simply the peritoneal cavity. A smaller portion of the upper posterior peritoneal cavity located posterior to the stomach is called the lesser sac. This sac has a special name—the omentum bursa.  Abdominal Cavity Retroperitoneal and Infraperitoneal Organs Retroperitoneal Organs Structures closely attached to the posterior abdominal wall ⚬ kidneys and ureters, adrenal glands, pancreas, C- loop of duodenum (aspect adjacent to head of pancreas), ascending and descending colon, upper rectum, abdominal aorta, and inferior vena cava. ⚬ These retroperitoneal structures are less mobile and move around less within the abdomen than other intraperitoneal organs. Infraperitoneal Organs Located under or beneath the peritoneum in the true pelvis are the lower rectum, urinary bladder, and reproductive organs.  Abdominal Cavity Male Versus Female Peritoneal Enclosures One significant difference exists between male and female peritoneal enclosures. The lower aspect of the peritoneum is a closed sac in the male but not in the female. In males, the lower peritoneal sac lies above the urinary bladder, totally separating the reproductive organs from the organs within the peritoneal cavity. In females, the uterus, uterine (fallopian) tubes, and ovaries pass directly into the peritoneal cavity  Abdominal Cavity Intraperitoneal Organs Organs within the abdominal cavity that are partially or completely covered by some type of visceral peritoneum but are not retroperitoneal or infraperitoneal may be called intraperitoneal (intra, meaning “within”). liver, gallbladder, spleen, stomach, jejunum, ileum, cecum, and transverse and sigmoid colon.  Quadrants and Regions To facilitate description of the locations of various organs or other structures within the abdominopelvic cavity, the abdomen may be divided into four quadrants or nine regions.  Abdominal Cavity Four Abdominal Quadrants  Abdominal Cavity Nine Abdominal Regions 1. Right hypochondriac 2. Epigastric 3. Left hypochondriac 4. Right lateral (lumbar) 5. Umbilical 6. Left lateral (lumbar) 7. Right inguinal (iliac) 8. Pubic (hypogastric) 9. Left inguinal (iliac)  Topographic Landmarks Abdominal borders and organs within the abdomen are not visible from the exterior, and because these soft tissue organs cannot be palpated directly, certain bony landmarks are used for this purpose.  Topographic Landmarks Seven landmarks of the 1.Xiphoid process (level of T9-T10): The tip of the adbomen xiphoid process is the most distal or inferior process of the sternum. This landmark approximates the superior anterior portion of the diaphragm, which is also the superior margin of the abdomen. 2.Inferior costal (rib) margin (level of L2-L3): This landmark is used to locate upper abdominal organs, such as the gallbladder and stomach. 3.Iliac crest (level of L4-L5 vertebral interspace): The crest of the ilium is the uppermost portion of the curved border of the ilium. The uppermost or most superior portion of this crest is the most commonly used abdominal landmark and corresponds approximately to the level of the midabdomen  Topographic Landmarks Seven landmarks of the 4.Anterior superior iliac spine (ASIS): The ASIS can be found by locatingadbomen the iliac crest, then palpating anteriorly and inferiorly until a prominent projection or “bump” is felt (more prominent on females) 5.Greater trochanter: This landmark is more easily palpated on thin patients. The prominence of the greater trochanter is at about the same level as the superior border of the symphysis. 6. Symphysis pubis: The symphysis pubis is the anterior junction (joint) of the two pelvic bones. This landmark corresponds to the inferior margin of the abdomen. However, palpation of this area may be embarrassing to some patients.  Topographic Landmarks Seven landmarks of the 7. Ischial tuberosity: This landmark can be used to adbomen determine the lower margin on a PA abdomen with the patient in a prone position. The lower margins of the ischial tuberosities are about 1 to 4 cm (112 inches) below or distal to the symphysis pubis. This landmark may be used for posi- tioning a PA projection of the colon when the rectal area is to be included on the IR. However, this may be uncomfortable and embarrassing for the patient, and other landmarks can and should be used when possible. Questions? Thank You