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Lecture 4

ZOO 3733C Lecture Notes - Lecture 4: Sickle-Cell Disease, Pyelonephritis, Gluten

Course Code
ZOO 3733C
Mohtashem Samsam

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Abdominal cavity:
4 important cavities within the body: the cranium, the thoracic, the abdomen + the pelvic cavity
The abdomen, is the largest cavity that has a lot of flat sheet like muscles with aponeurosis.
Fascia aid in structural protection, which can hinder us during clinical points
The Abdominal cavity
Is a closed cavity + within it, there is a two membrane system, the lining of the cavity is called
the peritoneum this is another serous membrane, the parietal peritoneum + the visceral
peritoneum are the components
Surface Anatomy
Quadrants: Right Upper Quadrant, Left Upper Quadrant, Left Lower Quadrant, Right Lower
Regions: there are 9 of them, using the belly button there is an umbilical region, right + left
lumbar, above the umbilical is epigastric region (above the belly), on the left + right of the
epigastric is hypochondriac regions (below costal cartilage of the ribs), hypogastric (below the
belly), left + right side of hypogastric, is the inguinal region
The inguinal regions, are areas of vulnerability
In males, the spermatic cord runs through the inguinal canal
In females, tendons run through the inguinal canal that are important later in life
Transpyloric plane: where umbilical stops, + epigastric starts
Left + right lateral lines
The abdominal cavity has NO bones, only spinal cord which helps with posture + a passageway
for nerves
Unique Muscles of the Abdomen
Medial lateral
3 muscles help the structural support:
The oblique muscles: external oblique muscles, they run pointing toward the pubic symphysis,
then is the internal oblique which run pointing toward the sternum + the transverse abdominis
muscle which runs horizontally
These have large sheaths + have large attachment areas, they are called aponeurosis which
extend past the obliques + transverse abdominis + meet up at the linea albathe anchor for all
these muscles is called the rectus sheath
Rectus abdominis, is another muscle found here
Pyrimidalis is inferior to the belly button
All of these muscles are innervated by the 6 intercostal nerves + L1, which help with the
compression of the viscera
The wet weight for intestines in a healthy adult is between 12-20 pounds
These muscles are also important for expiration
External abdominal oblique, the origin is the 5th and the 12th ribs, the rest is continuous with
the aponeurosis + meet up at the linea alba
The bottom of the aponeurosis is the iliac crest and is called the inguinal ligament. These can
fold + roll uniquely on themselves, which is important for tethering muscle to the iliac crest
Superficial inguinal ring: goes all they way down into the abdominal ring, inside of this will pass
is the inguinal canal; the medial crus or crust or superior/ interior crust which is broad + thin +
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attaches to the pubis symphysis while the inferior crust is for insertion of pubic tubercle
together is formed the superficial portion of inguinal ring
Internal oblique muscle origin is iliac crest, insertion on lower margin of last 3 ribs + onto the
rectus abdominis muscle
The aponeurosis of the external abdominal oblique goes over the rectus abdominis muscle, the
internal oblique has a thin layer over + under the rectus abdominis **this vulnerability is called
a hernia
The caudal portion of the internal oblique muscle, continues all the way down and in the male it
becomes a part of the spermatic cord called the cremaster muscle. This muscle allows the
testicles to relax further away from the body or when the muscle contracts it pulls the testes
closer to the body
For fertility, it is important to know that the testes need to be kept 5 degrees cooler than the
body temperature or else sperm will die.
Increase in temp further away
Decrease in temp closer
In females the caudal portions of the internal oblique muscle continues as the round ligament
of the uterus, this has an insertion at pectineal line or pectin pubis
Cremaster muscle, attaches to testes + is innervated by the genital branch of the genitofemoral
nerve because of how it is innervated in males with the upper portion of the thigh if it is
stroked, the cremaster muscle will contract and pull the testes up which is called the
cremaster reflex
Clinical abnormalities, if the inner portion of the thigh is stroked and there is no contraction
then there is some nerve damage whether it may be compressed or if there is a mass
Rectus Sheath is the aponeurosis of the external + internal abdominal obliques, increases
structural integrity
It is also for a protective area for some nerves + blood vessels, organs are suspended + nerves
need to be protected from compression, we use fibrous connective tissue as anchoring points,
inferior + superior epigastric nerves, arteries, + veins + 5 lower intercostal nerves + subcostal
Superior epigastric artery origin is internal thoracic which is subclavian which is arch of aorta
Inferior epigastric artery is from external iliac which is from common iliac
Superior + inferior epigastric arteries anastomose, these connects or restores a collateral
circulation between subclavian + iliac arteries or veins, ** we have two nerves the
iliohypogastric + ilioinguinal which do not sit in this area of the rectus sheath, which innervate
the pubic area + medial portion of the thigh
Othe fasia, is fist Cape’s fasia hih is a suutaeous fatt lae, it is ipotat fo
insulation, protection + under extreme circumstances it aids in some energy consumption
Net is “apa’s fasia
On posterior wall, of anterior portion of the abdominal cavity, there are unique folds of
ligaments, there are 5 of them: median, medial, lateral; these are kickbacks of embryonic
development becuasein utero our waste is rerouted. In median, urical cord, median umbilical
fold or middle umblical fold. The urical cord is the remnant of the bladder and the alantose,
which is an extra embryonic membrane. The medial ligaments are remnants of the umbilical
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Within this fascia, there are superficial veins + arteries, the most important one is the umbilical
veinous plexus, that drains into the portal systemaka the liver. This gives drainage for
lymphatics as well
Portal hypertension, increase in BP starting from the portal vein, because of the unique
circulation that can be caused by the excess BP running through it then that blood will get
aked up + go ito othe aeas, he that BP aks up eough it’ll eah the eious pleus
because they are connected + this becomes engorged, in late stage liver disease + cirrhosis,
there is the head of medusa looking veins (caput medusa)
Vulnerabilities are tears in aponeurosis, like the linea alba or the lateral line which is where the
rectus abdominis is. Hernia is a break where small or large intestine pushes out.
Aponeurosis are avascular, therefore it is difficult for a wound to heal
The initial break, a scar will form and there is possibility for a second hernia
Increase in abdominal pressure, congenital
Ex: pregnancy
The Abdominal cavity
Although the abdomen and pelvis are considered separately, their walls, their contents,
and cavities are continuous with each other.
Their upper and lower limits are muscular
Superiorly, the diaphragm separates the abdominal cavity from the thoracic cavity.
Inferiorly, the pelvic diaphragm separates the pelvis from the perineum
Large part of the abdominal wall is muscular, especially anteriorly and laterally
Posteriorly, the lumbar vertebrae are in the mid-line.
The pelvic walls are bony and are covered by muscles.
Transpyloric Plane
Crosses tips of 9th costal cartilages anteriorly and lower 1st lumbar vertebra posteriorly
The organs found in this level:
o Pylorus, superior part of the duodenum, duodenojejunal flexure, fundus of
Abdominal wall and the inguinal region
Superficial abdominal muscles
Lateral group:
o External and internal abdominal oblique muscles and the transverse abdominis
o External abdominal oblique muscles
The aponeurosis of the right and left muscles are interwoven and form
the linea alba
The lowest portion of this aponeurosis is continuous with the inguinal
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