Abdomen

Question 1

Answer 1

1. Costal cartilages
2. Iliac crest
3. Anterior superior iliac spine
4. Anterior inferior iliac spine
5. Superior pubic ramus
6. Pubic arch
7. Pecten pubis
8. Greater trochanter of femur
9. Ischial spine
10. Iliac crest
11. Xiphoid process
12. Body of sternum

Clinical: Imaginary lines mentally drawn on the surface of the abdominal wall assist clinicians in localizing pain and associated anatomic structures. The subcostal line is an imaginary horizontal line across the lower margin of the costal cartilages;it crosses the descending duodenum. The transumbilical plane is a horizontal line passing through the umbilicus and the L3-4 intervertebral disc. The transtubercular plane passes through the iliac tubercles of the iliac crest and corresponds to the body of the 5th lumbar vertebra.

Another clinically useful way to locate painful viscera is to divide the abdomen into quadrants. This is done by visualizing an imaginary vertical (median) plane from the xiphoid process to the pubic symphysis and a horizontal (transumbilical) plane. The 4 quadrants are the right upper quadrant, left upper quadrant, right lower quadrant, and left lower quadrant.

Question 2

Answer 2

1. External oblique muscle:muscular part (A) and aponeurotic part (B)

Origin: Arises by fleshy digitations from the external surfaces and inferior borders of the lower 8 ribs.

Insertion: The muscle attaches to the anterior half of the iliac crest, to the anterior superior iliac spine, and into a broad aponeurosis along a line from the 9th costal cartilage to the anterior superior iliac spine. The aponeurosis inserts into the midline linea alba.

Action: Compresses the abdominal contents. Contracting bilaterally, the muscles flex the vertebral column or trunk. Acting alone, the muscle bends the vertebral column laterally and rotates it so as to bring the shoulder of the same side forward.

Innervation: Supplied by intercostal nerves T7-11 and the subcostal nerve (T12).

Comment: This is the largest and most superficial of the 3 flat abdominal muscles.

Clinical: On the left side (patient’s left), one can see the fatty Camper’s fascia and the underlying membranous (Scarpa’s) fascia of the abdominal wall. These fascial planes are important in the spread of infection. Fluid from the perineal region (e.g., resulting from a ruptured urethra) can spread into the abdominal wall between Scarpa’s fascia and the underlying investing (deep) fascia of the external abdominal oblique muscle and aponeurosis.

Question 3

Answer 3

1. Internal oblique muscle

Origin: Arises from the lateral half of the inguinal ligament, the iliac crest, and the thoracolumbar fascia.

Insertion: Attaches to the inferior borders of the cartilages of the last 3 or 4 ribs, the linea alba, the pubic crest, and the pectineal line.

Action: Compresses the abdominal contents. Contraction of both internal oblique muscles flexes the vertebral column. Contraction on one side only bends the vertebral column laterally and rotates it, moving the shoulder of the opposite side anteriorly.

Innervation: By the intercostal nerves T7-11, subcostal nerve (T12), and iliohypogastric and ilio-inguinal nerves (L1).

Comment: In the inguinal region, the aponeuroses of the internal oblique and transverse abdominal muscles fuse to form the conjoint tendon.

Clinical: A weakness in the anterior abdominal wall can lead to hernias, where underlying viscera and fat may protrude anteriorly and cause a bulge or rupture of the anterior muscle layers. The most common types of abdominal wall hernias are inguinal hernias, umbilical hernias, linea alba hernias (usually occurring in the epigastric region), and incisional hernias (occurring at the site of a previous surgical scar).

Question 4

Answer 4

1. Rectus abdominis muscle

Origin: Arises inferiorly by 2 tendons. The lateral tendon is attached to the pubic crest, and the medial tendon interlaces with the tendon of the opposite side to arise from the pubic symphysis.

Insertion: Attaches into the cartilages of the 5th, 6th, and 7th ribs and the xiphoid process.

Action: Flexes the vertebral column or trunk, tenses the anterior abdominal wall, and depresses the ribs.

Innervation: Intercostal nerves (T7-11) and the subcostal nerve (T12).

Comment: The rectus abdominis muscle is contained in the rectus sheath and is separated from the rectus abdominis on the other side by the linea alba.

The muscle is crossed by fibrous bands, which are the 3 tendinous intersections;this gives the appearance of “6-pack abs.”

Clinical: If abdominal pain is present, especially if the affected visceral structure (e.g., bowel, appendix) comes in contact with the inner aspect of the peritoneal wall, the patient may present with a guarding reflex. The patient will contract the abdominal wall muscles when palpated (rebound tenderness) because of the abdominal pain, and the abdomen will become rigid.

Question 5

Answer 5

1. Cremaster muscle

Origin: This thin muscle arises from the middle of the inguinal ligament and is a continuation of the internal abdominal oblique muscle.

Insertion: Attaches by a small tendon to the pubic tubercle and crest.

• *Action**: Draws the testes upward.
• *Innervation**: Genital branch of the genitofemoral nerve (L1 and L2).

Comment: After passing through the inguinal ring, the muscle fibers of the cremaster form a series of loops that are embedded in the cremasteric fascia (surrounding the spermatic cord in a male).

The spermatic cord is covered by 3 fascial layers derived from the abdominal wall. The external spermatic fascia is derived from the external abdominal oblique aponeurosis;the middle spermatic (cremasteric) fascia, from the internal abdominal oblique muscle; and the internal spermatic fascia, from the transversalis fascia.

Clinical: The testes normally descend into the scrotum shortly before birth. This is necessary for viable germ cell division and future sperm production. The human testes will not produce sperm if the testis is not cooled to several degrees below that of the body’s normal temperature (37°C [98.6°F]).

Question 6

Answer 6

1. Superior epigastric vessels
2. Rectus abdominis muscle
3. Transversus abdominis muscle
4. Posterior layer of rectus sheath
5. Inferior epigastric vessels
6. Inguinal ligament (Poupart’s ligament)
7. Inguinal falx (conjoint tendon)
8. Cremasteric muscle (middle spermatic fascia)
9. Lacunar ligament (Gimbernat’s ligament)
10. Medial umbilical ligament (occluded part of umbilical artery)
11. Arcuate line
12. Transversalis fascia
13. Anterior layer of rectus sheath
14. Linea alba

Comment: Above the arcuate line, the anterior layer of the rectus sheath comprises the fused aponeuroses of the external and internal abdominal oblique muscles, whereas the posterior layer comprises the fused aponeuroses of the internal abdominal oblique and transversus abdominis muscles. Below the arcuate line, the aponeuroses of all 3 muscles fuse to form the anterior layer of the sheath;and the rectus abdominis muscle rests only on the thin transversalis fascia.

Clinical: The inferior epigastric vessels form the lateral umbilical fold and anastomose with the superior epigastric vessels, which are continuous with the internal thoracic (mammary) vessels. This arterial vascular anastomosis is important in providing blood to the abdominal wall, because these arteries have connections all along their route with intercostal arteries (in the thorax) and segmental lumbar branches in the abdomen.

Question 7

Answer 7

1. Quadratus lumborum muscle
   * *Origin**: Arises from the transverse processes of L3-5, the iliolumbar ligament, and the iliac crest.

Insertion: Attaches to the lower border of the last rib and the transverse processes of L1-3 vertebrae.

Action: With the pelvis fixed, this muscle laterally flexes the lumbar vertebral column (trunk). It also fixes the 12th rib during inspiration. When both quadratus lumborum muscles act together, they can help extend the lumbar vertebral column.

Innervation: Subcostal nerve (T12 and L1-4 nerves).

Comment: Superiorly, the diaphragm forms the lateral arcuate ligament (lumbocostal arch) where it passes over the quadratus lumborum.

Clinical: The lumbocostal triangle (located just lateral and superior to the lateral arcuate ligament) is a nonmuscular area between the costal and lumbar portions of the diaphragm. During trauma or with increased abdominal pressure, this portion of the diaphragm can become weakened and viscera can herniate into the thorax superiorly.

Question 8

Answer 8

1. Diaphragm

Origin: This dome-shaped musculofibrous septum arises from the circumference of the thoracic outlet, with fibers arising from a sternal portion (xiphoid process), a costal portion (lower 6 costal cartilages), and a lumbar portion (L1-3 vertebrae).

Insertion: The muscles converge and insert into the central tendon.

Action: Attached to the ribs and lumbar vertebrae, the muscular diaphragm draws the central tendon downward and forward during inspiration. This increases the volume of the thoracic cavity and decreases the volume of the abdominal cavity.

Innervation: Phrenic nerve (C3, C4, and C5).

Comment: The diaphragm has 3 large openings:the caval hiatus for the inferior vena cava (at the level of the T8 vertebra), the esophageal hiatus (at the level of the T10 vertebra), and the aortic hiatus (in front of the T12 vertebra).

Where the diaphragm passes over the aorta, it forms an arch called the median arcuate ligament. As the diaphragm passes over the psoas major muscle, it forms the medial arcuate ligament;and where it passes over the quadratus lumborum, it forms the lateral arcuate ligament.

Clinical: If an inflamed visceral structure (e.g., gallbladder) contacts the underside of the diaphragm, the parietal peritoneum may become inflamed and the pain will be passed along the sensory axons of the phrenic nerve (C3-5) on the right side to the corresponding dermatomes in the lower neck and shoulder region. This is an example of referred pain from the abdomen to a somatic region of the body.

Question 9

Answer 9

1. Right greater and lesser splanchnic nerves
2. Right sympathetic trunk
3. 2nd and 3rd lumbar
4. splanchnic nerves
5. Pelvic splanchnic nerves
6. Right and left hypogastric
7. nerves to inferior hypogastric (pelvic) plexus
8. Superior hypogastric plexus
9. Inferior mesenteric ganglion
10. Superior mesenteric ganglion and plexus
11. Celiac ganglia
12. Vagal trunks:Anterior and Posterior

Comment: Sympathetic and parasympathetic nerves innervate the viscera of the abdominal cavity. Sympathetic nerves coursing in the thoracic splanchnic nerves (from T5-12 spinal cord levels) and lumbar splanchnics (upper lumbar levels) synapse largely in 3 major collections of ganglia:celiac, superior mesenteric, and inferior mesenteric ganglia. A nerve plexus continuing from this most inferior ganglion gives rise to the superior hypogastric plexus, which provides sympathetic innervation to pelvic viscera.

Parasympathetic innervation to the upper two thirds of the abdominal viscera (derived from the foregut and midgut portions of the embryonic gut) comes from the vagus nerve. The remaining portions of the abdominal and pelvic viscera (embryonic hindgut) receive parasympathetics from S2, S3, and S4 via pelvic splanchnic nerves.

Most of these autonomic fibers reach the viscera by traveling on the blood vessels originating from the celiac trunk and the superior and inferior mesenteric arteries.

Clinical: Autonomic fibers to the bowel synapse on ganglion cells of the enteric nervous system, an intrinsic plexus of ganglia (myenteric and submucosal) for fine control of bowel function.

Question 10

Answer 10

1. Dorsal root (spinal) ganglion
2. White ramus communicans
3. Gray ramus communicans
4. Ganglion of sympathetic trunk
5. Superior mesenteric ganglion
6. Celiac ganglion
7. Vagus nerve (CN X)
8. Ventral (anterior) root
9. Intermediolateral cell column

Comment: This schema shows the general pattern for sympathetic and parasympathetic innervation of abdominal viscera.

Preganglionic sympathetic fibers can synapse in ganglia of the sympathetic trunk, course via splanchnic nerves to synapse in collateral ganglia such as the celiac or superior mesenteric ganglion (this example), or pass directly to the adrenal medulla (not shown).

Parasympathetic fibers to the upper two thirds of the abdominal viscera are conveyed by the vagus nerve, which sends preganglionic fibers directly to the walls of the organs innervated. These fibers
end in terminal ganglia in the visceral wall, which give rise to short postganglionic fibers.

Clinical: Pain sensation from the bowel (largely from distention or inflammation) is conveyed by afferent fibers whose nerve cell bodies reside in the dorsal root ganglia of the T5-L2 spinal levels. Therefore, visceral pain is often referred to somatic regions of the body corresponding to the dermatomes supplied by the spinal cord segment that receives the visceral afferent (sensory) input. This is called referred pain.

Question 11

Answer 11

1. Greater splanchnic nerve
2. Celiac ganglia and plexus
3. Superior mesenteric ganglion
4. Inferior mesenteric ganglion
5. Sympathetic trunk and ganglion
6. Superior hypogastric plexus
7. Pelvic splanchnic nerves
8. Inferior hypogastric (pelvic) plexus with peri-ureteric loops and branches to lower ureter

Comment: A rich plexus of sympathetic nerves arising from the superior mesenteric ganglion courses to the kidneys. Sympathetics to pelvic viscera arise from the superior hypogastric plexus formed below the inferior mesenteric ganglion. These nerves course on either side of pelvic viscera to the inferior hypogastric plexus.

Parasympathetic fibers to the kidneys arise from the vagus nerve. Pelvic viscera and lower abdominal viscera receive their parasympathetic fibers from pelvic splanchnic nerves arising from S2, S3, and S4 spinal cord levels.

Clinical: The pain (renal colic) of a renal stone that passes from the kidney and into the ureter is usually felt from the loin to the groin as the stone works its way toward the urinary bladder in the pelvis. The pain is conveyed by visceral afferents to the corresponding dorsal root ganglia of the spinal cord (T11-L2); thus, the pain is localized to these dermatomes.

Question 12

Answer 12

1. Duodenum and head of the pancreas
2. Gallbladder
3. Liver
4. Cecum and colon
5. Sigmoid colon
6. Kidney
7. Small intestine
8. Spleen
9. Stomach
10. Liver, gallbladder, and duodenum (irritation of diaphragm)
11. Gallbladder
12. Liver

Comment: Pain afferents from the abdominal viscera pass to the spinal cord largely by following the thoracic and lumbar splanchnic sympathetic nerves (T5-L2). Visceral pain may be perceived as somatic pain (skin and skeletal muscle) over these respective dermatomes and is called referred pain.

The nerve cell bodies of the afferent fibers from the viscera are located in the dorsal root ganglia of the respective spinal cord levels.

Clinical: Most visceral pain is related to irritation from inflammation, ischemia, distention, or compression. Knowing the location to which visceral pain is referred on the body’s surface is important in clinical diagnosis. Some visceral pain (e.g., from the stomach, gallbladder, and spleen) is referred to both the anterior and posterior body walls, as shown in the image.

Question 13

Answer 13

1. Subclavian vein
2. Axillary vein
3. Lateral thoracic vein
4. Anterior intercostal veins
5. Internal thoracic vein
6. Inferior epigastric veins
7. Superficial epigastric vein
8. Superficial epigastric vein
9. Thoraco-epigastric vein
10. Lateral thoracic vein
11. Jugular veins (External; Internal; Anterior)

Comment: The veins of the anterior abdominal wall provide an important superficial anastomotic network of veins that returns blood to the heart. These veins include anastomoses between the superficial epigastric veins, which drain the inguinal region, and the lateral thoracic veins, which drain into the axillary vein. On a deeper plane, the inferior epigastric veins anastomose with the superficial epigastric veins and the internal thoracic (mammary) veins.

In this illustration, a superficial dissection of the veins is shown in the fatty subcutaneous tissue on one side and on a deeper plane of dissection within the abdominal wall musculature on the other side.

Clinical: Just as in the limbs and head and neck regions, the thoracic and abdominopelvic regions have both a superficial and a deep venous arrangement, with numerous interconnections between these veins. These connections (anastomoses) ensure that venous blood can return to the heart via different routes if need be (which is important if a venous route is obstructed).

Question 14

Answer 14

1. Testicular vessels and genital branch of the genitofemoral nerve
2. Inferior epigastric vessels
3. Medial umbilical ligament (occluded part of umbilical artery)
4. Rectus abdominis muscle
5. Median umbilical ligament (urachus)
6. Superficial inguinal rings
7. Intercrural fibers
8. Inguinal ligament (Poupart’s ligament)
9. Cremasteric muscle
10. Spermatic cord
11. Internal spermatic fascia (from transversalis fascia at deep inguinal ring)
12. External abdominal oblique muscle
13. Internal abdominal oblique muscle
14. Transversus abdominis muscle
15. Transversalis fascia
16. Peritoneum

Comment: The inguinal canal extends from the deep inguinal ring to the superficial inguinal ring. In males, the spermatic cord traverses this canal.

Clinical: Indirect inguinal hernias (75% of inguinal hernias) occur lateral to the inferior epigastric vessels, pass through the deep inguinal ring and inguinal canal, and are enclosed within the internal spermatic fascia of the spermatic cord.

Direct inguinal hernias occur medial to the inferior epigastric vessels (Hesselbach’s triangle), pass through the posterior wall of the inguinal canal, and are separate from the spermatic cord.

Question 15

Answer 15

1. Abdominal aorta
2. Celiac trunk
3. Left hepatic artery
4. Cystic artery
5. Hepatic artery proper
6. Right gastric artery
7. Gastroduodenal artery
8. Right gastro-omental (gastro-epiploic) artery
9. Common hepatic artery
10. Left gastro-omental (gastro-epiploic) artery
11. Short gastric arteries
12. Splenic artery
13. Left gastric artery

Comment: Branches of the celiac trunk supply adult derivatives of the embryonic foregut and the spleen, a mesodermal derivative. The celiac trunk gives rise to the left gastric artery, the common hepatic artery, and the splenic artery. These primary branches distribute arterial blood to the liver and gallbladder;portions of the pancreas; and the spleen, stomach, and proximal duodenum.

Clinical: This epigastric region of the abdominal cavity is clinically important because pain secondary to pathophysiologic processes is common in this area. Vital structures, such as the stomach, duodenum, spleen, pancreas, liver, and gallbladder, all reside in this general region or refer pain to this region and to dermatomes related to the T5-9 or T10 spinal levels. Because
so many structures and vessels are in this epigastric region, physicians must obtain a thorough history and perform a physical examination to localize the site(s) of epigastric pain.

Question 16

Answer 16

1. Superior mesenteric artery
2. Middle colic artery
3. Straight arteries (arteriae rectae)
4. Marginal artery
5. Right colic artery
6. Ileocolic artery (Colic branch; Ileal branch)
7. Appendicular artery
8. Superior rectal artery
9. Sigmoid arteries
10. Left colic artery
11. Inferior mesenteric artery
12. Jejunal and ileal (intestinal) arteries

Comment: The superior mesenteric artery supplies blood to the adult gastrointestinal tract derivatives of the embryonic midgut. These include arteries to a portion of the pancreas, the distal duodenum, all of the small intestine, the appendix, the ascending colon, and most of the transverse colon.

The inferior mesenteric artery supplies the embryonic hindgut derivatives:the distal transverse colon, descending and sigmoid colon, and superior portion of the rectum.

Clinical: Anastomotic channels exist between the branches of the superior and inferior mesenteric arteries. If the blood flow from one bowel region is compromised, collateral flow from anastomotic branches usually can assist in supplying blood to the compromised region.

Question 17

Answer 17

1. Inferior phrenic arteries
2. Celiac trunk with common
3. hepatic, left gastric, and
4. splenic arteries
5. Middle suprarenal artery
6. Right renal artery
7. 1st to 4th right lumbar arteries
8. Common iliac arteries 7. Internal iliac artery
9. External iliac artery
10. Inferior epigastric artery
11. Inferior mesenteric artery 11. Abdominal aorta
12. Testicular (ovarian) arteries
13. Superior mesenteric artery

Comment: The abdominal aorta enters the abdomen via the aortic hiatus (T12 vertebral level) in the diaphragm and divides into the common iliac arteries anterior to the L4 vertebra.

The abdominal aorta supplies blood to the abdominopelvic viscera and posterior abdominal wall. The 3 unpaired vessels supplying the gastrointestinal tract are the celiac artery and the superior and inferior mesenteric arteries. Paired branches to glandular structures include the middle suprarenal, renal, and gonadal arteries. Parietal branches to the posterior abdominal wall include the inferior phrenic arteries, 4 pairs of lumbar arteries, and a small median sacral artery.

Clinical: Aneurysms (arterial wall bulges) of large arteries may occur for a variety of reasons. The abdominal aorta inferior to the origin of the renal arteries and above the aortic bifurcation is a common site for aortic aneurysms. The iliac arteries also are often involved. Surgical repair is usually warranted, especially if there is a danger of rupture.

Question 18

Answer 18

1. Right middle suprarenal artery
2. Right renal artery and vein
3. Abdominal aorta
4. Superior mesenteric artery (cut)
5. Left testicular (ovarian) artery and vein
6. Left inferior suprarenal artery
7. Left inferior phrenic artery
8. Esophagus

Comment: The abdominal aorta gives rise to 3 paired arteries that supply glandular structures of the abdominopelvic cavity. The paired arteries are the middle suprarenal arteries, the left and right renal arteries, and the left and right gonadal (ovarian or testicular) arteries.

As endocrine glands, the suprarenal glands receive a rich arterial supply from inferior phrenic arteries, directly from middle suprarenal arteries arising from the aorta, and from inferior suprarenal arteries arising from the renal vessels.

The suprarenal (adrenal) glands and the kidneys are retroperitoneal organs. The right kidney lies slightly lower than the left kidney, owing to the presence of the liver on the right side. The right adrenal gland usually is pyramidal, and the left adrenal gland is usually semilunar.

Clinical: Because of the segmental development of the kidneys and their lobulated appearance, it is not uncommon for there
to be several renal arteries and/or veins associated with the kidneys. Therefore, surgeons operating in this region of the abdomen must be aware of the variability in the renal vessels.

Question 19

Answer 19

1. Inferior phrenic veins
2. Inferior vena cava
3. Right renal vein
4. 1st to 4th right lumbar veins
5. Common iliac vein
6. External iliac vein
7. Internal iliac vein
8. Common iliac vein
9. Ascending lumbar veins
10. Ovarian (testicular) veins

Comment: The inferior vena cava pierces the diaphragm at the level of the T8 vertebra and enters the right atrium of the heart. Just inferior to the diaphragm, 2 or 3 hepatic veins drain blood from the liver into the inferior vena cava.

Principal tributaries of the inferior vena cava correspond to many of the arterial branches arising from the abdominal aorta. Commonly, these tributaries include the common iliac veins, pairs of lumbar veins, gonadal (testicular or ovarian) veins, renal veins, azygos vein, suprarenal veins, inferior phrenic veins, and hepatic veins. Veins draining the gastrointestinal tract and spleen form the portal venous system.

Clinical: Veins vary in number and arrangement and possess numerous connections with veins lying superficial or deep, as well as with veins of specialized systems such as the portal system draining the gastrointestinal tract. These veins do not have valves, and blood flow may occur in either direction depending on the pressure gradient propelling the blood.

Question 20

Answer 20

1. Para-umbilical veins
2. Right gastric vein
3. Hepatic portal vein
4. Superior mesenteric vein
5. Middle colic vein
6. Right colic vein
7. Ileocolic vein
8. Inferior rectal veins
9. Middle rectal veins
10. Left and right superior rectal veins
11. Left colic vein
12. Inferior mesenteric vein
13. Splenic vein
14. Left gastric vein
15. Esophageal veins

Comment: The hepatic portal vein is formed by the union of the splenic vein and superior mesenteric vein.

Clinical: Important portosystemic anastomotic sites include sites around the esophagus, the para-umbilical region, the rectum, and where portions of the gastrointestinal tract are in a retroperitoneal position.

If portal blood flow is decreased or prevented from flowing through the liver, the venous blood still can reach the heart via these important portosystemic anastomoses. Likewise, if the inferior vena cava is partially compressed or obstructed, venous blood can flow via the portosystemic anastomoses into the portal system of veins.

Question 21

Answer 21

1. Greater omentum (turned up)
2. Transverse colon (turned up)
3. Right colic (hepatic) flexure
4. Small intestine (jejunum and ileum)
5. Ascending colon
6. Cecum
7. Urinary bladder

Comment: The abdominopelvic cavity is a potential space. Parietal peritoneum lines the inner aspect of the abdominal walls and reflects onto the viscera as visceral peritoneum.

Portions of the ascending, transverse, and descending colon can be seen framing the small bowel, which consists of the jejunum and ileum in this illustration. The fatty greater omentum is turned up but remains attached to the bowel margin.

Clinical: If a portion of the peritoneal cavity or its contents becomes inflamed, the greater omentum can migrate to the site of inflammation and wall off the site by forming an adhesion, potentially protecting the remainder of the cavity. Because of its ability to wall off an infection site, the greater omentum is sometimes referred to as the abdomen’s “policeman.”

Also, the greater omentum often is a site for the metastatic spread of cancer from multiple primary sites.

Question 22

Answer 22

1. Stomach (posterior surface)
2. Probe in omental (epiploic) foramen
3. Gallbladder
4. Descending (2nd) part of duodenum
5. Head of pancreas (retroperitoneal)
6. Transverse mesocolon
7. Left colic (splenic) flexure
8. Spleen
9. Left suprarenal (adrenal) gland (retroperitoneal)

Comment: The greater omentum has been severed in this illustration, and the stomach has been elevated to show the lesser sac (the remainder of the abdominopelvic cavity is called the greater sac) residing posterior to the stomach and anterior to the retroperitoneal pancreas.

A probe enters the lesser sac through the epiploic foramen of Winslow. Anterior to the epiploic foramen lies the hepatoduodenal ligament, which is a portion of the lesser omentum (the other part is the hepatogastric ligament). Within the hepatoduodenal ligament one finds the hepatic artery proper, the common bile duct, and the portal vein.

Only a portion of the 2nd part of the duodenum is visible in this illustration. Similar to the pancreas, the duodenum is secondarily retroperitoneal.

Clinical: A perforated gastric ulcer in the posterior wall of the stomach could spill gastric contents into the lesser sac, and its acidic juices may erode into the pancreas. Likewise, cancer of the pancreas could invade the duodenum, stomach, or spleen because of its close proximity to these structures.

Question 23

Answer 23

1. Inferior vena cava
2. Omental (epiploic) foramen (of Winslow)
3. Portal triad (Common bile duct; Hepatic portal vein; Hepatic artery proper)
4. Omental bursa (lesser sac)
5. Pancreas
6. Stomach
7. Spleen
8. Left kidney
9. Splenic vein
10. Abdominal aorta

Comment: The omental bursa, or lesser sac, resides posterior to the stomach and anterior to the pancreas, which lies retroperitoneally. Access to the lesser sac is through a small foramen called the epiploic foramen of Winslow. The rest of the abdominopelvic cavity is referred to as the greater sac.

The portal triad lies within the hepatoduodenal ligament, which is part of the lesser omentum (the other part is the hepatogastric ligament). Just posterior to this triad, one can access the inferior vena cava (the inferior vena cava and aorta are retroperitoneal).

Clinical: Note the location of the pancreas and its close proximity to a number of important epigastric structures, including the duodenum, stomach, spleen, left kidney and adrenal gland, and aorta and inferior vena cava. Cancer from or trauma to the pancreas can have implications for any one of these structures that lies close to this important retroperitoneal organ.

Question 24

Answer 24

1. Common hepatic duct
2. Cystic duct
3. Superior (1st) part of duodenum
4. Hepatic ducts (Right; Left)
5. Cystic duct (Spiral fold; Smooth part)
6. Common bile duct
7. Pancreatic duct
8. Hepatopancreatic ampulla (of Vater)

Comment: Bile leaves the liver by the right and left hepatic ducts, draining into a common hepatic duct. The latter drains via the cystic duct into the gallbladder, which concentrates and stores bile. When stimulated by autonomic nerves and cholecystokinin, the gallbladder contracts, sending bile down the cystic duct. The bile flows through the common bile duct to the major duodenal papilla, which empties into the descending duodenum. At this location, the common bile duct joins the main pancreatic duct to form the hepatopancreatic ampulla of Vater.

Clinical: Gallstones occur in 10% to 20% of adults;risk factors include increased age, obesity, and being female. About 80% of gallstones are cholesterol stones, and about 20% are pigment (bilirubin calcium salts) stones. Gallstones can block the flow

of bile from the gallbladder to the duodenum and cause inflammation (cholecystitis) or block the hepatopancreatic ampulla and impede exocrine secretion from the pancreas. The pain of acute cholecystitis may be felt in the right upper abdominal quadrant, radiating laterally just beneath the right breast to the back just below the inferior angle of the right scapula.

Question 25

Answer 25

1. Coronary ligament
2. Fissure for ligamentum venosum
3. Porta hepatis
4. Gallbladder
5. Quadrate lobe
6. Bare area
7. Round ligament (ligamentum teres) of liver (obliterated umbilical vein) forming free border of falciform ligament
8. Falciform ligament

Comment: Visceral peritoneum reflects off the liver in the form of the falciform ligament and the coronary ligaments, which reflect off the right and left lobes of the liver and onto the underlying diaphragm. The bare area of the liver marks the portion of the liver not covered by visceral peritoneum because it is in direct contact with the diaphragm.

The round ligament of the liver is the obliterated umbilical vein. It
is visible in the free margin of the falciform ligament. The round ligament joins the ligamentum venosum, which is the fused ductus venosus from the fetus. Before birth, this passageway allows umbilical blood coming from the placenta to bypass the liver and drain directly into the inferior vena cava and pass to the fetal heart.

The liver is the largest solid organ in the body (the skin is the largest nonsolid organ) and functions in the production and secretion of bile; storage of nutrients;production of cellular fuels, plasma proteins,
and clotting factors;and detoxification and phagocytosis.

Clinical: Cirrhosis is a largely irreversible disease of the liver. Causes include alcoholic liver disease (60% to 70% of cases), viral hepatitis, biliary diseases, genetic hemochromatosis, and cryptogenic cirrhosis.

Question 26

Answer 26

1. Anastomotic loop (arcade) of jejunal arteries
2. Straight arteries (arteriae rectae)
3. Circular folds (valves of Kerckring)
4. Anastomotic loops (arcades) of ileal arteries
5. Serosa (visceral peritoneum)
6. Aggregate lymphoid nodules (Peyer’s patches)

Comment: The small intestine includes the duodenum (secondarily retroperitoneal), the jejunum (mesenteric), and the ileum (mesenteric). The jejunum constitutes the proximal two-fifths and the ileum the distal three-fifths of the mesenteric small intestine.

Several gross characteristics distinguish the jejunum from the ileum. The jejunum is larger in diameter and has longer straight arteries branching from its arterial arcades. It also has less fat in its mesentery and prominent circular folds of mucosa (plicae circulares) in its interior wall. More distally in the small bowel, the concentration of aggregated lymphoid nodules (Peyer’s patches) increases.

Clinical: Crohn’s disease is an idiopathic inflammatory bowel disease that may affect any segment of the gastrointestinal tract but usually involves the small intestine and colon. The disease presents with abdominal pain (in the periumbilical region or lower right quadrant), diarrhea, fever, and several other symptoms and is most common between the ages of 15 and 30 years.

Question 27

Answer 27

1. Greater omentum (cut away)
2. Transverse colon
3. Omental (epiploic) appendices (fat)
4. Ascending colon
5. Ileal orifice
6. Cecum
7. Appendix
8. Rectum
9. Sigmoid mesocolon
10. Sigmoid colon
11. Taeniae coli
12. Descending colon
13. Haustra
14. Semilunar folds

Comment: The large intestine includes the cecum (and the appendix), ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anal canal.

Sacs of fat (omental appendices), longitudinal smooth muscle bands called taeniae coli (3 bands exist), and haustra are characteristic features of the colon. Functionally, the colon is responsible for dehydration and compaction of indigestible materials for elimination. The reabsorption of water and electrolytes and provision of host defense mechanisms also are important functions.

The transverse and sigmoid colon are intraperitoneal and are tethered by a mesentery.

Clinical: Colorectal cancer is 2nd only to lung cancer in site-specific mortality rates and accounts for almost 15% of cancer-related deaths in the United States.

Question 28

Answer 28

1. Cortex
2. Medulla (pyramids)
3. Renal papilla
4. Medullary rays
5. Ureter
6. Minor calices
7. Renal pelvis
8. Major calices
9. Renal column

Comment: At the gross level, the interior of the human kidney is divided into an outer cortical layer and inner medullary layer.

At its apex, each medullary pyramid has a renal papilla in which the collecting ducts of the nephron deliver urine to minor and major calices. Several major calices coalesce to form the renal pelvis, which exits the kidney at its hilum and forms the ureter. The ureter conveys urine to the urinary bladder.

Clinical: Kidney stones (renal stones, nephrolithiasis) can form in the kidney and enter the urinary collecting system, where they may cause renal colic (loin to groin pain) and obstruction of the flow of urine from the kidney to the urinary bladder. The 3 most common sites of obstruction occur at the ureteropelvic junction at the hilum of the kidney, where the ureter crosses the common iliac vessels, at the pelvic brim, and at the ureterovesical junction as the ureter passes through the bladder’s detrusor muscle wall.

Question 29

Answer 29

1. Liver
2. Lesser omentum
3. Omental bursa (lesser sac)
4. Transverse mesocolon
5. Transverse colon
6. Small intestine
7. Urinary bladder
8. Rectum
9. Inferior (horizontal, or 3rd) part of duodenum
10. Pancreas

Comment: Reflections of the parietal and visceral peritoneum and their intervening mesenteries can be seen in this sagittal section.
The stomach, small intestine (jejunum and ileum portions), transverse colon, and sigmoid colon are suspended in the peritoneal cavity by mesenteries. The other portions of the gastrointestinal tract are secondarily retroperitoneal.

Clinical: The abdominopelvic cavity is a potential space, normally containing only a small amount of serous lubricating fluid that allows the viscera to glide easily over one another during gastrointestinal peristalsis. The abnormal accumulation of serous fluid in this potential space is called ascites. Ascites can occur for a variety of reasons. In liver cirrhosis, the sinusoidal hypertension (portal hypertension) can contribute up to 10-20 L/day of weeping hepatic lymph that may collect in the peritoneal cavity and greatly distend the abdomen.

Question 30

Answer 30

1. Liver
2. Falciform ligament
3. Portal vein
4. Inferior vena cava
5. Omental bursa (lesser sac)
6. Right kidney
7. Abdominal aorta
8. Left suprarenal (adrenal) gland
9. Splenorenal ligament with splenic vessels
10. Spleen
11. Gastrosplenic ligament with short gastric vessels
12. Stomach
13. Rectus abdominis muscle (in rectus sheath)
14. Lesser omentum

Comment: In this cross section of the abdomen, the intraperitoneal viscera are represented by the liver, stomach, and spleen. Retroperitoneal viscera lying beneath the parietal peritoneum in the posterior abdominal wall include the right and left kidneys, suprarenal (adrenal) glands, aorta, and inferior vena cava.

Within the hepatoduodenal portion of the lesser omentum, one can see the portal vein, common bile duct, and hepatic artery proper.

Clinical: Note that the kidneys and adrenal glands are retroperitoneal organs, which lie posterior to the parietal peritoneum covering the posterior abdominal wall. Therefore, in some instances, these organs may be accessed surgically without entering the peritoneal cavity, thus reducing the chance for intra-abdominal infection.

Question 31

Answer 31

1. Ileum
2. Ascending colon
3. Right paracolic gutter
4. Psoas major muscle
5. Inferior vena cava
6. Abdominal aorta
7. Intervertebral disc (between L2 and L3 vertebral bodies)
8. Descending colon
9. Loops of jejunum
10. Internal oblique muscle
11. Greater omentum
12. Omental appendices (fat)
13. Linea alba
14. Transverse colon

Comment: This cross section of the lower abdominopelvic cavity shows the loops of the small bowel suspended by a mesentery. Also visible are portions of the ascending, transverse, and descending colon. The ascending and descending colon are secondarily retroperitoneal, having been pushed against the posterior abdominal wall during embryonic development of the gastrointestinal tract.

Clinical: Note the relationships of the abdominal viscera to
the posterior, lateral, and anterior abdominal wall muscles. The greater omentum drapes over the intestines like a fatty apron and can “wall off” sites of inflammation within the peritoneal cavity by forming adhesions to protect the rest of the viscera. The adhesions develop as the inflamed visceral peritoneum scars and forms connective tissue with adjacent peritoneal surfaces. The adhesions may become significant and limit bowel motility, leading to reduced or obstructed flow through a bowel segment.