Download Gastro06-AbWallPeritonealCavityPt2

GI, #6
Mon, Feb. 17, 2:00pm
Dr. Roque
Deana Lanham for Cynthia Schleuter
Page 1 of 4
HUMAN ANATOMY:
Anterior Abdominal Wall and Peritoneal Cavity II
Synopsis of Anatomy Lecture I
1. For the TEST:
a. Remember the different planes and their associated vertebral levels. Review the
transpyloric plane and the structures associated with this plane.
b. Understand the position and significance of the arcuate line. The posterior rectus sheath
is defective below this line. Know and understand the different layers that form the
rectus sheath. (Moore 124, N235).
c. Know also the different structures found in the rectus sheath (Moore 124, N234).
d. It is important to know the lymphatic drainage and where infections or metastasis
may/may not spread. For superficial structures (skin and superficial fascia), the anterior
axillary lymph nodes drain the area above the umbilicus, and the superficial inguinal
nodes drain the area below the umbilicus. Deeper structures have to use more deeper
nodes mostly found inside the abdominal cavity (lumbar nodes, common illiac nodes,
external iliac nodes).
Clinical Relevance: Ruptured Urethra (Moore 122)
1. Scarpa’s fascia, the membranous part of the superficial fascia, attaches just below the groin area
into the deep fascia of the thigh (fascia lata).
2. A space exists between the Scarpa’s fascia and the deep fascia covering the rectus
abdominis. This space connects into the groin and scrotal area inferiorly.
3. Fluid may potentially accumulate in this area. If the urethra ruptures urine will accumulate in
this space. The abdomen will appear reddish due to irritation from the urine.
4. This liquid will NOT EXTEND IN THE THIGH because of the attachment of the Scarpa’s
fascia to the fascia lata a few inches below the inguinal ligament.
Description of the Inguinal Canal and Spermatic Cord (Moore 130-132, N242-245)
1. As the testes descend during development, they must push through the wall of the abdominal
cavity and become surrounded by the different connective tissue layers oderived from the
muscles of the anterior abdominal wall. The spermatic cord (the stalk of the testes) follows and
serves as the main blood supply and nerve source for the testes.
2. The external oblique forms the anterior wall of the inguinal canal. The transversalis fascia and
the conjoint tendon form the posterior wall. The inguinal and lacunar ligaments form the floor.
3. The inguinal canal contains the spermatic cord in males and the round ligament of the uterus
in females.
4. In N236, we are looking at the posterior aspect of the anterior abdominal wall. Here we are
looking at the innermost layer of the abdominal wall. Observe the spermatic cord and the deep
inguinal ring.
5. The deep inguinal ring is the entrance into the inguinal canal and is the outpocketing of the
transversalis fasica posterioly. It is positioned lateral to the inferior epigastric vessels.
6. The superficial inguinal ring is the exit from the inguinal canal anteriorly through the opening in
the external abdominal loblique aponeurosis. It is adjacent to the pubic tubercle.
GI, #6
Mon, Feb. 17, 2:00pm
Dr. Roque
Deana Lanham for Cynthia Schleuter
Page 2 of 4
7. The testes pass through this tunnel (inguinal canal) during its development. The vas deferens,
arteries and nerves to the testes pass through this tunnel to form the spermatic cord. The
ilioinguinal nerve (L1) passes through the canal and exits the superficial ring but does not enter
the deep ring.
8. These anatomical relationships can also be viewed on N243 & N245. Basically, you have two
openings that lead to a tunnel, which is known as the inguinal canal.
Abdominal Hernias
1. Definition: the protrusion of part of the abdominal contents beyond the normal confines of the
abdominal wall
2. Types:
a. Inguinal (most common one and will be discussed in detail)
b. Umbilical
c. Spigelian, along the lateral border of the rectus abdominis (linea semilunaris)
d. Internal
e. Femoral
f. Epigastric
g. Lumbar (at the lumbar triangle or Petit’s triangle)
h. Incisional (iatrogenic, usually following surgery)
i. Separation of the rectus abdominis muscle
Inguinal Hernias (Moore 138)
1. This is associated with the development of the testes in males. This can also occur in females, but
is more common in males.
2. When the testes develop, they develop together with the kidneys inside the abdominal cavity.
3. Due to the high temperature inside the abdominal cavity the testes must migrate to the outside
through the inguinal canal. Sterility will result if the testes do not migrate out, and this is referred
to as “undescended testes” or cryptorchidism.
4. Indirect Inguinal Hernia
a. An incomplete closure of the inguinal canal may cause structures to enter the canal
through the deep ring lateral to the inferior epigastric vessels. These structures may or
may not emerge out of the superficial ring.
i. The intestines, fat, or any other abdominalstructure, such as mesentery, in the
vicinity may form the indirect inguinal hernia.
b. It also has a hernial sac formed by the persistent processus vaginalis (the outpocketing of
the peritoneum which projects into the scrotum.)
c. This is a congenital problem common in CHILDREN, but may also be present in adults.
d. If you palpate the superficial inguinal ring (Moore 131) and ask your patient to cough, the
hernia will start to enlarge due to the increased pressure inside the abdomen.
Sometimes you can even put your finger into the superficial ring and try to push it back.
If you are able to push it then this means that the canal has not completely closed.
GI, #6
Mon, Feb. 17, 2:00pm
Dr. Roque
Deana Lanham for Cynthia Schleuter
Page 3 of 4
5. Direct Inguinal Hernia
a. A direct inguinal hernia is through a weakened conjoint tendon in the inguinal triangle,
and it is medial to the inferior epigastric vessels.
b. It is more common in ADULTS, especially in older males.
c. The conjoint tendon is a joint aponeurosis of the internal abdominal oblique and
transversus abdominis muscles. Netter refers to the conjoint tendon as the Inguinal falx.
d. Normally it is strong, but in adults it can become weakened. For example, if you are
lifting weights and you increase your abdominal pressure, then your intestine can bulge
through this area.
e. The problem with this is that sometimes you have a sac where the intestine can rotate
around and cause strangulation.
f. This bulges DIRECTLY through the anterior abdominal wall. It does not pass
through the inguinal canal.
Other Types of Hernias
1. The rectus abdominis can become weakened, particularly along the linea semilunaris. This can be
a site where the abdominal contents can penetrate through, resulting in a Spigelian hernia.
2. An incisional hernia is when a patient has abdominal surgery and it was not correctly done,
which then leads to a hernia.
3. The lumbar triangle, which is formed by the iliac crests, latisimus dorsi, and the external
abdominal oblique, is also a common site for a lumbar hernia.
Organ Classification (N329)
1. It is very important to understand how the structures develop and form within the abdominal wall
and viscera.
2. The organs are classified as either intraperitoneal (“peritonealized”) or retroperitoneal. Dr. Roque
prepared a visual demonstration in order for us to understand this better. Below is an explanation
of these demonstrations.
3. Demonstration: INTRAPERITONEAL ORGANS
a. Imagine you are holding a large Ziploc bag. The outside of the Ziploc bag represents the
outermost layer of the abdominal wall, or the skin. The inside of the bag represents the
ninth layer of the abdominal wall, or the extraperitoneal fatty layer. Thus, the Ziploc bag
represents the 9 layers of the abdominal wall.
b. A plastic bag that is CLOSED on both sides represents the 10th layer, or the
parietal peritoneum. It does not contain anything inside of it expect a small amount of
fluid, which is why textbooks often refer to it as a “potential space.”
c. Put this closed bag into the Ziploc bag and bunch it up. You now have 9 layers
(represented by the Ziploc bag) plus the 10th layer of the abdominal wall (represented by
the plastic bag).
d. Where are the organs? If you put an organ (represented by a small ball) into the Ziploc
bag along with the plastic bag, you would find that THE ORGANS ARE NOT INSIDE
THE PERITONEAL CAVITY. The peritoneum is a closed system and a potential
space. The organ is considered to be INSIDE the abdominal cavity but OUTSIDE of
the peritoneal cavity.
GI, #6
Mon, Feb. 17, 2:00pm
Dr. Roque
Deana Lanham for Cynthia Schleuter
Page 4 of 4
e. This is because during development organs develop in the extraperitoneal fatty layer from
mesenchymal tissue.
f. When the organs start to enlarge during development they grow inward and become
surrounded by the peritoneal cavity. Imagine if the ball in the Ziploc bag enlarged. It
would appear that the plastic sac would be
Intraperitoneal
Retroperitoneal
covering the entire organ. In this case,
are the organs inside the peritoneal
Stomach
Duodenum (rest)
cavity? NO.
Duodenum
(first)
Ascending colon
g. However, the organs are still covered by
Jejunum/ileum
Descending Colon
the peritoneum, and this is referred to as
V. appendix
Rectum
visceral peritoneum. These organs are
Cecum
Pancreas
now called INTRAPERITONEAL
Transverse Colon
Kidneys/Adrenals
ORGANS. Notice that the prefix is
Sigmoid Colon
Ureters
“intra” and not “inter.”
Liver/gall bladder
Major Vessels
Spleen
(Aorta, IVC)
h. In histology, the tunica serosa is actually
the visceral peritoneum.
4. Demonstration: RETROPERITONEAL ORGANS
a. On one side the organs will be covered by peritoneum and on the other side they are not
covered by peritoneum, and are thus considered to be partially covered.
b. Imagine our Ziploc bag with the plastic bag inside of it. Only one side of the organ is
covered by the peritoneum (plastic sac), but the other side is pressed up against the inner
wall of the Ziploc bag.
c. Keep these categories in mind when you dissect the various organs.
Note: The rest of the powerpoints for this lecture will be covered on Wednesday, February 19th.
The last part of the lecture dealt with a discussion on the dissector and various laboratory
procedures.
Dissector/Lab Discussion
1. The dissector has histology slides on it. Please look at these slides for the test.
2. It also has an upper and lower GI series and CAT Scans.
3. Most importantly, it contains lecture notes from Dr. Roque, and these will be posted on our
course website so we can print them. The lecture notes contain more information on them than
the powerpoints.
4. If there are ever any conflicts of the checklist, or the list of items that we are responsible for,
always refer to the written dissector as the final authority. If they are not on the checklist then
they will not be tested.
5. As far as the dissection procedures, make your first incision in the midline. Go around the
umbilicus, and go directly to the muscle layer. Don’t worry about dissecting the superficial
fascia. Refer to the dissector for the other dissection procedures.