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					SSN Anatomy #2                                            October 9, 2002

                            Abdomen Schmabdomen

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                      Strangulationnecrosis
Reversed rotation (situs inversus           Situs inversus
viscerum)
Malrotation                                 Small intestine may pass behind
                                            ascending or descending colon when it
                                            goes to be retroperitonealstrangulates
                                            small intestineparaduodenal 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 secretioninflammation
                                            of diverticulumulceration of ileum
                                            NOTE: rule of threes
2. Subdivisions of GI Tract: (A:25)

  Region        Structures        Arterial       Innervation       Spinal      Region of
                                  Supply                           Level     Referred Pain
              1)esophagus                      Parasympathetic:
              2)stomach        Celiac artery   Vagus n.                     Epigastric
              3)duodenum
 Foregut      4)liver          Hepatic         Sympathetic:        T5-T9    (Low central
              5)spleen         portal vein     Greater                      thorax)
              6)pancreas                       Splanchnic
              7)gall bladder
              1)jejunum                        Parasympathetic:
              2)ileum                          Vagus n.
              3)ascending      Superior                                     Umbilicus
  Midgut      colon            mesenteric      Sympathetic:        T10-
              4)transverse     artery          Lesser              T11      (hypogastric)
              colon                            Splanchnic n.
              5)appendix       Sup.
              6)colon          Mesenteric
                               vein
              1)Descending                     Parasympathetic:
              colon            Inferior        Pelvic splanchnic   S2,S3    Perineum,
                               mesenteric      n. (travel                   Post. thigh
 Hindgut      2)Sigmoid        artery          retrograde)
              colon
                               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
                   Functions                            Level
                 Internal       Upper gluteal,                     Afferent/efferent
Iliohypogastric oblique,        pubic regions          T12-L1,     limbs of abd.
                 Transverse                            Anterior    reflex
                 abd. m.
                 Internal       Upper medial thigh,
  Ilioinguinal   oblique,       root of penis or       L1,
                 transverse     mons pubis,            Anterior
                 abd. m         anterior labia
                                majora
Genitofemoral                                                      Efferent limb of
     -Genital    Cremaster      Anterior scrotum                   cremaster reflex
                 m.                                    L1-L2
    -Femoral                    Anterosuperior         Anterior    Afferent limb of
                                thigh                              cremaster reflex
      Lateral
     Femoral                    Lateral thigh          L2-L3
   Cutaneous                                           Posterior

   Femoral       Anterior       Anterior and medial L2-L4,
                 thigh          thigh and leg       Anterior

  Obturator      Medial thigh Medial thigh             L2-L4
                                                       Anterior
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
   Horizontal:
  Rectus Sheath       none                   Many = bloody          Difficult to suture
                                                                     can rip during
                                                                    valsalva fixation
                                                                    (eg. sneeze)
  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
                                                                    2.Prone to
                                                                    epigastric hernia
   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
                                                                    tearing
     Vertical:    Intercostal nerves         none                   1.Damage nerves
Lateral Abdominal                                                   loss of innervation
       Wall                                                         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       Site of emergence
    anterior wall
     Triangle of          1)Inf. Epigastric a. Direct Hernia         Superficial ring of
     Hasselbach           2)Linea                                    inguinal canal
                          semilunaris                                (weakness of ext.
                          3)Inguinal                                 oblique m)
                          ligament
                          1)Transversalis +     Indirect hernia      Superficial ring of
Deep Inguinal Ring int. oblique m                                    inguinal canal
                          2)Inf. Epigastric a
                          3)Inguinal ligam.
                          1)Inguinal
  Femoral Ring            ligament              Femoral hernia       Fossa ovalis of
                          2)Femoral vein                             great saphenous
                          3)Lacunar                                  vein
                          ligament
                          4)Pectineal
                          ligament

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           Dorsal mesointestine
diaphragm
Falciform ligament: contains round
ligament of the liver
Median umbilical fold: contains urachus,
runs from bladder to umbilicus (clinical:
patent urachus)
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.
                               pelvic cavity)


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           Liver lobe that is supplied
                                                                         or drained
Right hepatic artery           Right hepatic duct               Right lobe and half of
                                                                caudate lobe
Left hepatic artery            Left hepatic duct                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             Refers pain to:         Area of narrowing
Upper abdominal        Least splanchnic n.     T12 – inguinal ant.     Renal pelvis to
ureter                 (T12)                   And sup. Thigh,         ureter
                                               lower back
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,
                                               perineum

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

Cortex                             renal corpuscles, proximal and distal convoluted tubules
                                   12-18 renal pyramids - fuse @ apices to 8-12 renal
Medulla                            papillae

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

				
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