Surface projections of abdominal organs

Surface projections of abdominal organs Practical Handout 

Prepared by Dr. Sanjaya Adikari, Dept. of Anatomy, Faculty of Medicine

Surface Lines 

For convenience of description of the viscera and of reference to morbid conditions of the contained parts, the abdomen is divided into nine regions, by imaginary planes, two horizontal and two vertical, the edges of the planes being indicated by lines drawn on the surface of the body. The upper, or subcostal, horizontal line encircles the body at the level of the lowest points of the tenth costal cartilages; the lower, or intertubercular, is a line carried through the tubercles on the iliac crests about 5 cm behind the anterior superior spines. An alternative for the subcostal line is the transpyloric line that passes midway between the jugular notch and the top of the symphysis pubis. This line passes little above the subcostal line. By means of these horizontal planes the abdomen is divided into three zones named from above, the subcostal, umbilical, and hypogastric zones. Each of these is further subdivided into three regions by the two sagittal planes, which are indicated on the surface by a right and a left lateral line drawn vertically through points halfway between the anterior superior iliac spines and the symphysis pubis also passing through the midpoint of the clavicle. The middle region of the upper zone is called the epigastric, and the two lateral regions the right and left hypochondriac. The central region of the middle zone is the umbilical, and the two lateral regions the right and left lumbar. The middle region of the lower zone is the hypogastric or pubic, and the lateral are the right and left iliac or inguinal.

Stomach

The shape of the stomach is constantly undergoing alteration; it is affected by the particular phase of the process of gastric digestion, by the state of the surrounding viscera, and by the amount and character of its contents. Its position also varies with that of the body, so that it is impossible to indicate it on the surface with any degree of accuracy.

Duodenum

The superior part is horizontal and extends from the pylorus to the right lateral line; the descending part is situated medial to the right lateral line, from the transpyloric line to a point midway between the transpyloric and transtubercular lines. The horizontal part runs with a slight upward slope from the end of the descending part to the left of the middle line; the ascending part is vertical, and reaches the transpyloric line, where it ends in the duodenojejunal flexure, about 2.5 cm to the left of the middle line.

Small Intestine

The coils of small intestine occupy the front of the abdomen. For the most part the coils of the jejunum are situated on the left side, i.e., in the left lumbar and iliac regions, and in the left half of the umbilical region. The coils of the ileum lie toward the right in the right lumbar and iliac regions, in the right half of the umbilical region, and in the hypogastric region; a portion of the ileum is within the pelvis. The end of the ileum, i.e., the ileocolic junction, is slightly below and medial to the intersection of the right lateral and transtubercular lines.

Caecurn and appendix

The caecum is in the right iliac and hypogastric regions; its position varies with its degree of distension, but the midpoint of a line drawn from the right anterior superior iliac spine to the upper margin of the symphysis pubis will mark approximately the middle of its lower border. The position of the base of the appendix is indicated by a point on the lateral line on a level with the anterior superior iliac spine.

Spleen 

To map out the spleen the tenth rib is taken as representing its long axis; vertically it is situated between the upper border of the ninth and the lower border of the eleventh ribs. The highest point is 4 cm from the midline of the back at the level of the tip of the ninth thoracic spinous process; the lowest point is in the midaxillary line at the level of the first lumbar spinous process.

Kidneys 

The right kidney usually lies about 1 cm lower than the left, but for practical purposes similar surface markings are taken for each. On the front of the abdomen the upper pole lies midway between the plane of the lower end of the body of the sternum and the transpyloric plane, 5 cm from the middle line. The lower pole is situated midway between the transpyloric and intertubercular planes, 7 cm from the middle line. The hilum is on the transpyloric plane, 5 cm from the middle line. Round these three points a kidney-shaped figure 4 cm to 5 cm broad is drawn, two-thirds of which lies medial to the lateral line. To indicate the position of the kidney from the back, the parallellogram of Morris is used; two vertical lines are drawn, the first 2.5 cm, the second 9.5 cm from the middle line; the parallelogram is completed by two horizontal lines drawn respectively at the levels of the tips of the spinous process of the eleventh thoracic and the lower border of the spinous process of the third lumbar vertebra. The hilum is 5 cm from the middle line at the level of the spinous process of the first lumbar vertebra.