SSN Anatomy #2
October 9, 2002
Abdomen Schmabdomen
1 a) Abnormalities of Foregut rotation: (A: 24 II B)
Rotational Abnormality
Possible Sequelae
Pyloric stenosis
Duodenum fails to reopen its lumen 
Duodenal stenosis
Incomplete recanalization
1. b) Abnormalities of Midgut Rotation
Rotational Abnormality
Nonrotation of the gut
Reversed rotation (situs inversus
viscerum)
Malrotation
Withdrawal failure (incomplete retraction
from umbilicus)
Meckel’s Diverticulum
Possible Sequelae
Strangulationnecrosis
Situs inversus
Small intestine may pass behind
ascending or descending colon when it
goes to be retroperitonealstrangulates
small intestineparaduodenal hernia
Congenital umbilical herniation (need to
be careful when cutting umbilicus at
birth, may also cut part of gut)
Gastric mucosa secretioninflammation
of diverticulumulceration of ileum
NOTE: rule of threes
2. Subdivisions of GI Tract: (A:25)
Region
Foregut
Midgut
Structures
1)esophagus
2)stomach
3)duodenum
4)liver
5)spleen
6)pancreas
7)gall bladder
1)jejunum
2)ileum
3)ascending
colon
4)transverse
colon
5)appendix
6)colon
1)Descending
colon
Hindgut
2)Sigmoid
colon
3) rectum
Arterial
Supply
Celiac artery
Hepatic
portal vein
Innervation
Spinal
Level
Parasympathetic:
Vagus n.
Sympathetic:
Greater
Splanchnic
Region of
Referred Pain
Epigastric
T5-T9
(Low central
thorax)
Parasympathetic:
Vagus n.
Superior
mesenteric
artery
Umbilicus
Sympathetic:
Lesser
Splanchnic n.
T10T11
(hypogastric)
Sup.
Mesenteric
vein
Inferior
mesenteric
artery
Parasympathetic:
Pelvic splanchnic
n. (travel
retrograde)
Inf.
Mesenteric
vein
Sympathetic:
Lumbar
splanchnic n
S2,S3
Perineum,
Post. thigh
L1,L2
Pubic and
inguinal
region
3. Somatic Nerves of Posterior Abdomen
Nerve
Motor
Sensory Functions
Functions
Internal
Upper gluteal,
Iliohypogastric oblique,
pubic regions
Transverse
abd. m.
Internal
Upper medial thigh,
Ilioinguinal
oblique,
root of penis or
transverse
mons pubis,
abd. m
anterior labia
majora
Genitofemoral
-Genital
Cremaster
Anterior scrotum
m.
-Femoral
Anterosuperior
thigh
Lateral
Femoral
Lateral thigh
Cutaneous
Femoral
Obturator
Lumbosacral
Trunk
Anterior
thigh
Spinal
Level
T12-L1,
Anterior
Connects lumbar plexus to sacral
plexus – contributes to the sciatic
n. (posterior thigh, leg and foot)
Afferent/efferent
limbs of abd.
reflex
L1,
Anterior
Efferent limb of
cremaster reflex
L1-L2
Anterior
L2-L3
Posterior
Anterior and medial L2-L4,
thigh and leg
Anterior
Medial thigh Medial thigh
Associated Reflex
L2-L4
Anterior
L4-L5
anterior+
posterior
Afferent limb of
cremaster reflex
4.Access to the peritoneal cavity: (A: 23 IV A-B)
Incision
Vertical:
Rectus sheath
Nerve supply cut
Arterial supply cut
Intercostal nerves
supplying muscle
medial to incision
none
none
Many = bloody
Paramedian:
Rectus Sheath
None
None
Vertical:
Linea Alba
none
none
Must avoid
Iliohypogastric n.
none
Vertical:
Intercostal nerves
Lateral Abdominal
Wall
none
Horizontal:
Rectus Sheath
Transverse:
Ventrolateral
abdominal wall
Other pros & cons
Damage to nerves:
-atrophy of muscle
– poten. site of
ventral herniation
Difficult to suture
 can rip during
valsalva fixation
(eg. sneeze)
Can avoid rectus
abdominus m. by
moving it laterally
after skin incision
1.Doesn’t heal well
b/c no vasc. to area
2.Prone to
epigastric hernia
1.Incision is along
Langer’s lines
2.Can split muscle
fibers after skin
incision to avoid
tearing
1.Damage nerves
loss of innervation
to muscles medial
to incision
atrophy
2.Predisposition to
hernia
5. Potential sites of herniation: (A: 23 VII D-F)
Weakness in
Boundaries
Hernia type
anterior wall
Triangle of
1)Inf. Epigastric a. Direct Hernia
Hasselbach
2)Linea
semilunaris
3)Inguinal
ligament
1)Transversalis +
Indirect hernia
Deep Inguinal Ring int. oblique m
2)Inf. Epigastric a
3)Inguinal ligam.
1)Inguinal
Femoral Ring
ligament
Femoral hernia
2)Femoral vein
3)Lacunar
ligament
4)Pectineal
ligament
Site of emergence
Superficial ring of
inguinal canal
(weakness of ext.
oblique m)
Superficial ring of
inguinal canal
Fossa ovalis of
great saphenous
vein
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
below umbilicus)
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
hepatoduodenal ligament
Coronary ligaments: attach liver to
diaphragm
Falciform ligament: contains round
ligament of the liver
Median umbilical fold: contains urachus,
runs from bladder to umbilicus (clinical:
patent urachus)
Dorsal mesointestine
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
Foramen of Winslow
Subphrenic recess
Boundaries
Sup: caudate lobe of liver
Post: Inf. Vena cava
Inf: superior duodenum
Ant: hepatoduodenal
ligament
Anterior and superior to
liver, beneath diaphragm
Posterior to liver
Pouch of Morrison
Right colic gutter
Lateral to ascending colon
(communicates with
supracolic compartment,
pouch of Morrison and
pelvic cavity)
Clinical Significance
Omental herniation: If
loop passes through, none
of the boundaries can be
incised, bowel must be
deflected and withdrawn
Second most frequently
infected abdominal space,
pulmonary abscess may
erode across diaphragm
When supine it is the
lowest portion of the
abdominal cavity  fluid
will collect here, frequent
site of infection
Route for spread of
infection between pelvis
and upper abdominal
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
important?
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
Right hepatic artery
Right hepatic duct
Left hepatic artery
Left hepatic duct
Liver lobe that is supplied
or drained
Right lobe and half of
caudate lobe
Left lobe (smaller),
Quadrate, and half of
caudate
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
output)
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
Upper abdominal
Least splanchnic n.
ureter
(T12)
Lower abdominal
ureter
Lumbar splanchnic
n. (L1-L2)
Pelvic ureter
Pelvic splanchnic n
(S2-S4)
Refers pain to:
T12 – inguinal ant.
And sup. Thigh,
lower back
L1-L2 – inguinal,
pubic region, sup.
And ant. Thigh
S2-S4 – posterior
thigh, leg,
perineum
Area of narrowing
Renal pelvis to
ureter
Where ureter
crosses over pelvic
brim
Ureter to bladder
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
Clinical Cases
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
structures?
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 
i. appendicitis
ii. Meckel’s diverticulum
iii. volvulus
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?
Lumbar herniation
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
the pelvis.
“Quickies”
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
long.
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.
Kidney:
Which kidney lies lower in the abdominal wall and why? (385)
Right kidney, because of the liver.
Is the kidney supported by mesentary? (385)
No.
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)
Right: IVC
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
vesical arteries.
Internal Structure of the Kidney
Region of Kidney
Contents
Medulla
renal corpuscles, proximal and distal convoluted tubules
12-18 renal pyramids - fuse @ apices to 8-12 renal
papillae
Pelvis
collectes urine from kidney, narrows to ureter
Cortex
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