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A N A T O M Y FOR DIAGNOSTIC I M A G I N G
Fig. 5.4 CT scan: level of renal hila (L2). 1. Right lobe of liver 2. Aorta 3. Inferior vena cava 4. Right renal vein 6. Left renal artery
1 7 . Rectus abdominis muscle
7. Superior mesenteric artery
18. Transversus abdominis muscle
THE STOMACH (Figs 5.5-5.9) The stomach is J-shaped but varies in size and shape with the volume of its contents, with erect or supine position, and even with inspiration and expiration. The size and shape of the stomach also vary considerably from person to person, differing especially with the build of the subject. The stomach has two orifices - the cardiac orifice (so named because of proximity through the diaphragm to the heart) at the oesophagogastric junction, and the pylorus. It has two curvatures - the greater and lesser curves. The incisura is an angulation of the lesser curve.
19. Internal oblique muscle 2 0 . External oblique muscle
and superior mesenteric
2 1 . Latissimus dorsi muscle
artery
2 2 . Erector spinae muscle
9. Loops of small bowel
In the ruptured anterior urethra contrast can be seen to extravasate into the scrotum, perineum and penis, and then on to the lower abdominal wall because of the attachments of Scarpa's and Colles' fascia.
hemidiaphragm 16. Right renal pelvis
passing between aorta
Contrast urethrography
right hemidiaphragm 15. Lower end crus of left
5. Left renal vein
8. Third part of duodenum
Interventional procedures Skin punctures lateral to the rectus muscles, or in the midline, will avoid the epigastric vessels. Catheter placement that avoids the recti is also better tolerated.
14. Lower end crus of
2 3 . Gerota's fascia
10. Ascending colon
2 4 . Fascia of Zuckerkandl
1 1 . Transverse colon
2 5 . Lateral conal fascia
12. Descending colon
(fusion of Gerota's fascia
13. Psoas muscle
and fascia of Zuckerkandl)
The part of the stomach above the cardia is called the fundus. Between the cardia and the incisura is the body of the stomach, and distal to the incisura is the gastric antrum. The lumen of the pylorus is referred to as the pyloric canal. The stomach is lined by mucosa, which has tiny nodular elevations called the areae gastricae and is thrown into folds called rugae. Longitudinal folds paralleling the lesser curve are called the 'magenstrasse' meaning 'main street'. Rugae elsewhere in the stomach are random and patternless. There are three muscle layers in the wall of the stomach: (i) an outer longitudinal, (ii) an inner circular and (iii) an incomplete, innermost oblique layer. The circular layer is thickened at the pylorus as a sphincter, but not at the oesophagogastric junction. Fibres of the oblique layer loop around the notch between the oesophagus and the fundus and help to prevent reflux here. The oblique fibres are responsible for the 'magenstrasse' and can pinch off the remainder of the stomach and allow fluids to pass directly from oesophagus along the lesser curve to the duodenum. Peritoneum covers the anterior and posterior surfaces of the stomach and is continued between the lesser curve and the liver as the lesser omentum, and beyond the greater curve as the greater omentum. Anterior relations of the stomach The upper part of the stomach is covered by the left lobe of the liver on its right and by the left diaphragm on the left. The fundus occupies the concavity of the left dome of the diaphragm. The remainder of the anterior of the stomach is covered by the anterior abdominal wall. Posterior relations of the stomach (see Fig. 5.6) Posterior to the stomach lies the lesser sac (see Peritoneal spaces of the abdomen later in the chapter, and Figs 5.53 and 5.54). The structures of the posterior abdominal wall
