SSN Anatomy #2 October 9, 2002
1 a) Abnormalities of Foregut rotation: (A: 24 II B)
Rotational Abnormality Possible Sequelae
Duodenum fails to reopen its lumen Pyloric stenosis
Incomplete recanalization Duodenal stenosis
1. b) Abnormalities of Midgut Rotation
Rotational Abnormality Possible Sequelae
Nonrotation of the gut Strangulationnecrosis
Reversed rotation (situs inversus Situs inversus
Malrotation Small intestine may pass behind
ascending or descending colon when it
goes to be retroperitonealstrangulates
small intestineparaduodenal hernia
Withdrawal failure (incomplete retraction Congenital umbilical herniation (need to
from umbilicus) be careful when cutting umbilicus at
birth, may also cut part of gut)
Meckel’s Diverticulum Gastric mucosa secretioninflammation
of diverticulumulceration of ileum
NOTE: rule of threes
2. Subdivisions of GI Tract: (A:25)
Region Structures Arterial Innervation Spinal Region of
Supply Level Referred Pain
2)stomach Celiac artery Vagus n. Epigastric
Foregut 4)liver Hepatic Sympathetic: T5-T9 (Low central
5)spleen portal vein Greater thorax)
2)ileum Vagus n.
3)ascending Superior Umbilicus
Midgut colon mesenteric Sympathetic: T10-
4)transverse artery Lesser T11 (hypogastric)
colon Splanchnic n.
colon Inferior Pelvic splanchnic S2,S3 Perineum,
mesenteric n. (travel Post. thigh
Hindgut 2)Sigmoid artery retrograde)
Inf. Sympathetic: L1,L2 Pubic and
3) rectum Mesenteric Lumbar inguinal
vein splanchnic n region
3. Somatic Nerves of Posterior Abdomen
Nerve Motor Sensory Functions Spinal Associated Reflex
Internal Upper gluteal, Afferent/efferent
Iliohypogastric oblique, pubic regions T12-L1, limbs of abd.
Transverse Anterior reflex
Internal Upper medial thigh,
Ilioinguinal oblique, root of penis or L1,
transverse mons pubis, Anterior
abd. m anterior labia
Genitofemoral Efferent limb of
-Genital Cremaster Anterior scrotum cremaster reflex
-Femoral Anterosuperior Anterior Afferent limb of
thigh cremaster reflex
Femoral Lateral thigh L2-L3
Femoral Anterior Anterior and medial L2-L4,
thigh thigh and leg Anterior
Obturator Medial thigh Medial thigh L2-L4
Lumbosacral Connects lumbar plexus to sacral L4-L5
Trunk plexus – contributes to the sciatic anterior+
n. (posterior thigh, leg and foot) posterior
4.Access to the peritoneal cavity: (A: 23 IV A-B)
Incision Nerve supply cut Arterial supply cut Other pros & cons
Damage to nerves:
Vertical: Intercostal nerves none -atrophy of muscle
Rectus sheath supplying muscle – poten. site of
medial to incision ventral herniation
Rectus Sheath none Many = bloody Difficult to suture
can rip during
Paramedian: None None Can avoid rectus
Rectus Sheath abdominus m. by
moving it laterally
after skin incision
Vertical: none none 1.Doesn’t heal well
Linea Alba b/c no vasc. to area
Transverse: 1.Incision is along
Ventrolateral Must avoid none Langer’s lines
abdominal wall Iliohypogastric n. 2.Can split muscle
fibers after skin
incision to avoid
Vertical: Intercostal nerves none 1.Damage nerves
Lateral Abdominal loss of innervation
Wall to muscles medial
5. Potential sites of herniation: (A: 23 VII D-F)
Weakness in Boundaries Hernia type Site of emergence
Triangle of 1)Inf. Epigastric a. Direct Hernia Superficial ring of
Hasselbach 2)Linea inguinal canal
semilunaris (weakness of ext.
3)Inguinal oblique m)
1)Transversalis + Indirect hernia Superficial ring of
Deep Inguinal Ring int. oblique m inguinal canal
2)Inf. Epigastric a
Femoral Ring ligament Femoral hernia Fossa ovalis of
2)Femoral vein great saphenous
6.a) How is the arcuate line formed? (A: 28 III C)
Above the arcuate line, the rectus sheath consists of an antrerior portion (external
oblique aponeurosis and half of the internal oblique aponeurosis) and a posterior
portion (half of the internal oblique aponeurosis and the transverse aponeurosis).
Below the arcuate line, all aponeurotic layers pass anterior to the rectus abdominus
muscle. The lower free edge of the posterior sheath is the arcuate line –( 1-2 inches
b) What is its clinical significance?
Where the arcuate line meets the linea semilunaris is a potential site for herniation =
lateral ventral (spigelian hernia)
7. Primary derivatives of ventral and dorsal mesenteries. (A: 24 II A)
Ventral Mesentery Dorsal Mesentery
Lesser omentum: between stomach and Dorsal mesogastrium: contains
liver. gastrosplenic, gastrophrenic and greater
2 parts: gastrohepatic ligament, omentum
Coronary ligaments: attach liver to Dorsal mesointestine
Falciform ligament: contains round
ligament of the liver
Median umbilical fold: contains urachus,
runs from bladder to umbilicus (clinical:
8. Peritoneal subdivisions. (A: 338 Table 24-1)
Explain what each term means and give an example of each:
Retroperitoneal –develops outside peritoneum. Can be converted to adventitia or
peritoneum (Eg. Thoracic esophagus, rectum)
Peritoneal – has mesentery
(Eg. Transverse colon, jejunum, ileum)
Secondarily retroperitoneal –develops with mesentery and then it fuses with peritoneum
(Eg. Ascending and descending colon)
9. Peritoneal landmarks (A: 24 III B)
Peritoneal Structure Boundaries Clinical Significance
Sup: caudate lobe of liver Omental herniation: If
Foramen of Winslow Post: Inf. Vena cava loop passes through, none
Inf: superior duodenum of the boundaries can be
Ant: hepatoduodenal incised, bowel must be
ligament deflected and withdrawn
Anterior and superior to Second most frequently
Subphrenic recess liver, beneath diaphragm infected abdominal space,
pulmonary abscess may
erode across diaphragm
Posterior to liver When supine it is the
Pouch of Morrison lowest portion of the
abdominal cavity fluid
will collect here, frequent
site of infection
Lateral to ascending colon Route for spread of
Right colic gutter (communicates with infection between pelvis
supracolic compartment, and upper abdominal
pouch of Morrison and region.
12. a)Which vessels contribute to the marginal artery of the colon? (A p.377, Netter plate
287)The superior and inferior mesenteric arteries
b) What are three clinical significance points of the marginal artery and why are they
There is not a lot of collateral circulation at these three points:
1.splenic flexure – middle colic a. and descending left colic a.
2.rectosigmoid junction – rectosigmoid a. and superior rectal a.
3. ileocecal junction – ileal branch od sup. Mes. A. and ilealcolic a.
13. Liver vasculature and biliary drainage. (A: 25 II D)
Arterial Supply Biliary Drainage Liver lobe that is supplied
Right hepatic artery Right hepatic duct Right lobe and half of
Left hepatic artery Left hepatic duct Left lobe (smaller),
Quadrate, and half of
14. Trace the sympathetic and afferent innervation of the kidney:
Sympathetic: Preganglionic (T12-L2) – least splanchnic n – aorticorenal ganglion
(near renal a.) – postganglionic via renal plexus to kidney (function: decreased urinary
Afferent (Sensory): principal path follows symp. Pathway back via white rami
communicantes to T12, secondary path is through lumbar splanchnics to L1-L2
15. Ureter innervation (A: p. 390)
Part of Ureter Innervation Refers pain to: Area of narrowing
Upper abdominal Least splanchnic n. T12 – inguinal ant. Renal pelvis to
ureter (T12) And sup. Thigh, ureter
Lower abdominal Lumbar splanchnic L1-L2 – inguinal, Where ureter
ureter n. (L1-L2) pubic region, sup. crosses over pelvic
And ant. Thigh brim
Pelvic ureter Pelvic splanchnic n S2-S4 – posterior Ureter to bladder
(S2-S4) thigh, leg,
16. From where does the adrenal vasculature supply arise and to where does the venous
drainage empty? ( A p. 392)
Arterial: 1)Inferior phrenic a.- Superior suprarenal a.
2)aorta – middle suprarenal a.
3)renal a. – inferior suprarenal a.
Venous: 1)Right suprarenal v. - IVC
2)Left suprarenal v. – left renal v. – IVC
1. One day, a 48-year-old nurse practitioner comes to your office, complaining of a
“colicky” pain in the epigastric region. She notices that eating foods that are high in
fat exacerbates the pain. When you examine her, you find that she is jaundiced.
Upon taking her history, you also find that she has two children and that she had been
slightly obese until she started her “Deal-a-Meal” program a couple of months ago.
a. What do her symptoms and history indicate as a diagnosis?
Inflammation of the gall bladder = cholecystitis
(Predisposing factor: “Four F’s.” Female, fat, forty, and fertile.)
b. Upon further testing, you decide that a gallbladder removal is indicated. After
entering the peritoneum, what should you locate before clamping or severing any
Triangle of Calot.
c. What are the boundaries of this structure?
Cystic duct, liver, hepatic duct.
d. What is its significance?
There is a lot of variability in the arteries within the Triangle of Calot (e.g. cystic
artery, right hepatic artery, accessory bile duct). Structures should be clearly identified
before clamping or ligating.
2. In the ER, you are presented with a 13 y/o girl who complains of diffuse, colicky pain
in the umbilical region. Her dad says she is just faking a stomachache because she
wants to avoid going to a family reunion. You feel her abdomen and it shows no
guarding (i.e. no muscle contraction to protect peritoneum upon touch).
a. What is her differential diagnosis?
Umbilical region T10
ii. Meckel’s diverticulum
Due to several trauma cases that take you away, the girl and her father end up waiting for
three hours in the ER. The next time you come in, the girl is doubled over, her abdomen
displays guarding, and she shrieks when you press the lower-right quadrant.
a. Explain the guarding and the localized pain, and how this affects your diagnosis.
The infection has moved to the parietal peritoneum ( guarding or contraction of the
abdominal muscles to protect the peritoneum) and the pain has localized to a specific
region of the peritoneum. Diagnosis: appendicitis.
3. A 48 y/o male alcoholic visits his physician asking for treatment of painful
hemorrhoids. The patient’s liver is found to be enlarged, and a diagnosis of portal
hypertension is made.
a. What causes portal hypertension?
Cirrhosis of the liver
b. Name three other manifestations of portal hypertension.
i. Esophogeal varices
ii. Veins of Retzius (veins connect secondarily retroperitoneally to IVC)
iii. Caput medusae (in falciform ligament) = enlarged paraumbilical anastomoses.
c. What surgical means are used to circumvent portal hypertension?
i. Anastomose splenic and left renal vein to IVC
ii. Anastomose portal vein to IVC.
4. You’re a third-year medical student in the ER and a 50 y/o male comes in
complaining of lower back pain. You suspect kidney stones.
a. Given the location of his pain, where do you think the stone has lodged?
Lower back T12 renal pelvis to ureter narrowing
b. What is the best way to access the kidney at the renal pelvis?
Surgical access to the kidney is best via the lumbar trigone. The abdominal wall is thin
at this point. Boundaries: posteriolateral edge of external oblique, anterolateral border
of latissimus dorsi, superior aspect of iliac crest.
c. What complication is associated with this structure?
d. Upon surgical access to the kidney it is found that there is no stone, but rather an
acute kidney infection. How can this infection spread to other parts of the body?
Inferiorly, the renal fascia (=false fascia or Gerota’s fascia) is open. It forms
periureteral sheaths around each ureter. Infection can spread within the sheaths to
What’s the difference between the falx inguinalis and the conjoined tendon? (324)
Falx inguinalis: the lower, curving portion of the transverse abdominis muscle
and its aponeurosis. (sickle-shaped)
Conjoined tendon: the fusion between the internal oblique and the transverse
abdominis aponeurosis as they form the anterior wall of the rectus sheath.
What’s the “rule of 3’s” regarding a Meckel’s diverticulum? (365)
Occurs in 3% of adults, within 3 feet of iliocecal junction, and is less than 3 inches
What are the “lineas” that surround the rectus abdominis?
Lateral: Linea Semilunaris
Medial: Linea Alba
What three muscles comprise the posterior abdominal wall? (393)
Diaphragm, Quadratus Lumborum, and Iliopsoas
What’s the significance of the “bloodless line” at the gastroduodenal junction? (348)
Poor collateral circulation; to surgically remove the duodenum, you have to take out
the distal stomach.
Which kidney lies lower in the abdominal wall and why? (385)
Right kidney, because of the liver.
Is the kidney supported by mesentary? (385)
Name the three structures at the renal hilus. (386)
Renal pelvis, renal artery, and renal vein.
Where do the left and right gonadal and phrenic veins empty? (388)
Left: Left renal vein
Where is the kidney vascular and parenchymal pain principally referred? (388)h
T12: Least splanchnic nerve
The vascular supply of the ureters comes from: (390)
Everywhere. (Twigs from renal arteries, aorta, small arteries in the posterior
abdominal wall, gonadal arteries, common iliac arteries, internal iliac arteries, inferior
Internal Structure of the Kidney
Region of Kidney Contents
Cortex renal corpuscles, proximal and distal convoluted tubules
12-18 renal pyramids - fuse @ apices to 8-12 renal
Pelvis collectes urine from kidney, narrows to ureter
What is the 1-3-3 rule for internal kidney structure?
1 pelvis receives from 3 major calyces, each of which receives urine from 3 minor calyces
(each of which receive from 1-3 renal papillae
What are two relatively common variations in renal arterial supply?
1. Polar artery – arises directly from aorta
2. Hilar artery – arises from renal artery, usually smaller than polar artery
Renal Developmental Anomalies
Name of Developmental
Anomaly Effect of Anomaly
polycystic kidney collecting tubules don't join to form a calyx
horseshoe kidney 2 kidneys join across midline
lobated kidney maintain fetal segmentation (rarely a health problem)
ectopic kidney located in pelvis