Download Abdomen (plate 249) - located between the thorax and the pelvis

Abdomen (plate 249)
- located between the thorax and the pelvis
- surrounded by the abdominal wall
- separated from the thorax by the diaphragm
- continuous inferiorly with the pelvic cavity
Contains:
- peritoneum
- most of the digestive organs
- stomach
- intestines
- gall bladder
- liver
- pancreas
- spleen
- kidneys and adrenal glands
- parts of the ureters
Abdominal Wall
Divided into:
1- 9 Regions (tic tac toe)
- defined by 4 planes
A – Left Midclavicular
B – Right Midclavicular
C – Subcostal – below the 10th costal cartilage and posteriorly through L3
D – Transtubercular – runs through the iliac tubercles posteriorly through L5
Nine Regions
1- Right Hypochondriac
2- Left Hydrochondriac
3- Epigastric (between left and right hypochondriac)
4- Right Lumbar (below right hypochondriac)
5- Right Inguinal (below right lumbar)
6- Left Lumbar
7- Left Inguinal
8- Umbilical (below epigastric)
9- Suprapubic (below umbilical)
Right
Midclavicular
Left
Midclavicular
Right Hypochondriac
Epigastric
Left Hypochondriac
Right Lumbar
Umbilical
Left Lumbar
Right Inguinal
Suprapubic
Left Inguinal
Subcostal
Transtubercular
2- 4 Quadrants
By:
Median Plane – straight down midline
Transumbilical – right through the belly button
Four Quadrants
1- Right Upper Quadrant
2- Right Lower Quadrant
3- Left Upper Quadrant
4- Left Lower Quadrant
Wall of the Abdomen
Anteriolateral Abdominal Wall
Boundaries:
- costal cartilages 7-10 (bilaterally)
- xiphoid process (superiorly)
- inguinal ligaments (bilaterally boarder of femoral triangle) and pelvic bones (inferiorly)
Contains:
- skin
- subcutaneous connective tissue
- muscles
- fascia
- peritoneum
Superficial Fascia (of AL Wall)
- over most of the wall
Consists of:
- a layer with varying amounts of fat
- in the inferior part of the AL Wall, down near the inguinal regions, the fascia is divided into
two layers:
1- Superficial Layer – “camper’s fascia”
- primarily fat tissue
2- Membranous Layer (deep to camper’s fascia) – “scarpas’ fascia”
- only in inferior part
Tranversalis Fascia
- firm membranous sheet
- lines most of the abdominal wall
- covers the deep surface of the transversus abdominus muscle tissue
- continuous with the linear alba on the right and left sides
Parietal Peritoneum
- internal to the transversalis fascia
- separated from it by varying amounts of extra peritoneal fat
Muscles of the Anteriolateral Abdominal Wall
Four Muscles
Of the four muscles, THREE are categorized as being flat, and ONE is vertical
ALL of these muscles function to compress and support the abdominal viscersa
- involved in SOME trunk flexion
(from most superficial to deep)
A - Flat Muscles
1 – External Oblique
- most superficial
- its fibers pass inferiomedially (down and to the mid line)
- interdigitate (mingle) with the fibers of the serratus anterior
- course:
- proximal and distal – from external surface of ribs 5-12, to the linear alba
on both side
- anteriorly – runs down to the iliac crest
2 – Internal Oblique
- intermediate of the flat muscles
- fibers run at right angles to the external oblique
- course:
- starts on the anterior 2/3 of the iliac crest and the inguinal ligament to the
inferior border of ribs 10-12
3 – Transversus Abdominus
- innermost of the three flat muscles
- fibers run horizontally (not at angles)
- course:
- from the interior surfaces of costal cartilages 7-10 and lateral half of the
inguinal ligament to the linear alba bilaterally (on both side)
B – Vertical Muscle
1- Rectus Abdominus
- vertical strap-like muscle
- most of it is enclosed in the rectus sheath
- anterior layer of this sheath – firmly attached to the rectus muscle at
three tendonus insertions
- FIRST - at level of the xiphoid
- SECOND - at level of the umbilicus
- THIRD - midway in between those two
- “six pack”
ALL THREE FLAT MUSCLES end anteriorly in a strong apopneurosis
- this forms the rectus sheath
In addition to providing protection for the abdominal viscera, the 4 muscles INCREASE
intrabdominal pressure
- Aids in:
- force expiration
- defication
- micturition (urination)
- parturition (childbirth)
Nerves of the Anterior Abdominal Wall
Thoracoabdominal Intercostal Nerves
Formed from:
- ventral rami of T7 – T12 and L1
Distribution of nerves
Ventral rami of:
T7 – T9 - supply the skin above the umbilicus
T10 - around the umbilicus
T11, 12 and L1 – below the umbilicus
Vessels of the AL Wall
Superior Epigastric Vessels
- arise from internal thoracic vessels
Inferior Epigastric Vessels
- arise from the external iliac artery
Internal Surface of the AL Wall
- Covered with parietal peritoneum
- the umbilical part of the peritoneum carries remnants of blood vessels from the fetus
Inguinal Canal
- an oblique inferiomedially directed canal (from sides toward midline running downwards)
- provides a passageway for the spermatic cord through the inferior part of the anterior
abdominal wall
- lies parallel to and just superior to the medial half of the inguinal ligament
Contents:
- spermatic cord (in males)
- round ligament of the uterus (in females)
- ilioinguinal nerves (in males AND females)
The Canal has:
- an anterior wall – formed from fibers of the external and internal oblique muscles
- a posterior wall – formed from the transversalis fascia and the conjoint tendon (formed from
the internal oblique and the transversalis abdominus)
- roof – formed from the transversalis muscle and the internal oblique
- floor – formed the superior surface of the inguinal ligament
**The deep inguinal ring is an outpouching (little pouch) that is formed from the transversalis
fascia at the midpoint of the inguinal ligament
- there are hernias associated with the deep inguinal ring
Spermatic Cord
- suspends the testes in the scrotum
- contains structures that are running TO and FROM the testes
- Begins at the deep inguinal ring
- it is lateral to the inferior epigastric artery
- passes through the inguinal canal and ends on the posterior border of the testes within the
scrotum
- surrounded by fascia from the abdomen
Three Layers (of fascia):
1- internal spermatic fascia – from the transversalis fascia
- innermost – it is from the innermost muscle (transversalis fascia)
2- cremasteric fascia – from the internal oblique
- contains muscle fibers which compose the cremastor muscle
- when it contracts - draws the testes superiorly within the scrotum
3- external spermatic fascia – from the external oblique
Dartos muscle – within the wall
- helps regulate temperature in the testes – by shrinking the testes
Contents: (of spermatic cord):
- ductus deferens (vas deferens)
- testicular artery – arise from the abdominal aorta
- artery to the ductus deferens – comes off vesicular artery
- cremasteric artery – comes off inferior epigastric
- pampinoform plexus – venous network
- sympathetic and parasympathetic fibers on the vas deferens
- genital nerves
- lymphatic vessels
Reproductive Physiology
Parasympathetic Division – erection
Sympathetic Division – ejaculation
Pneumonic Device – “Point and Shoot”
Scrotum
- a cutaneous sac
Consists of two layers:
1- skin
2- superficial fascia
- contains fibers of the dartos muscle
- contracts in response to cold temperature – helping to regulate the
internal temperature in the scrotum
Arteries to the Scrotum
Branches of:
- internal pudental
- external pudental right off the femoral artery
- inferior epigastric
Scrotal Veins
- parallel the arteries of the same name
Nerves
- pudental nerves branches – arises from S2, S3, S4
-genitofemoral nerves from L1 and L2
-illioinguinal nerves from L1
Testes
Function:
- spermatogenesis
- testosterone synthesis
Surface of each testi is covered by:
- a double layered peritoneal sac called the tunica vaginalis
- epididymus – collects the sperm as its being produced
- directs it to the vas deferens
Testicular Artery
- arises from the abdominal aorta, right below the renal arteries
Veins from the Testes
- join at the pampiniform plexus
Testes Contain:
Parasympathetic Fibers – vagal in origin
Sympathetic Fibers – from T7
Terms Used to Describe Peritoneum and Structures Associated with Peritoneum w/in Abdominal
Cavity
Peritoneum – transparent, continuous serous membrane
Consists of two layers:
1- Parietal Peritoneum
- lines the abdominal cavity
2- Visceral Peritoneum
- covers the viscera (physically on the viscera)
Peritoneal Cavity – space between the layers
- a potential space – because the organs are very tightly packed in the abdomen
All serous membranes – have serous fluid (lubricating) - to allow movement of organs over
eachother
The peritoneal cavity is:
- CLOSED in males
- OPEN in females where the uterine tubes, uterus, and vagina are located
The peritoneum and ALL viscera are within the abdominal cavity
Intraperitoneal Organs
- covered by visceral peritoneum
Extraperitoneal (Retroperitoneal) Organs
(kidneys, pancreas, ascending and descending colon)
- these viscera located between the parietal peritoneum and the posterior abdominal wall
Various terms are used to describe parts of the peritoneum
Mesentery – a double layer of peritoneum that begins as an extension of visceral peritoneum on
an organ
- covers visceral organs
- connects an organ to a body wall
- have a core of connective tissue – connects structures to body wall
- Contain:
- blood vessels
- lymphatic vessels
- nerves
- fat
- lymph nodes
Viscera within a mesentery are mobile
- amount of movement depends on length of mesentery
Omentum
- specific to the stomach
- double layered extension of visceral peritoneum
- runs from the stomach to the proximal part of the duodenum and then to another organ or
structure
A- Lesser Omentum
- connects the lesser curvature of the stomach and the proximal part of the
duodenum to the liver
B- Greater Omentum
- arises from the greater curvature of the stomach and the first part of the
duodenum, descends, and then folds back up to attach to the transverse colon
Ligaments (associated with peritoneum and viscera)
1- Falciform Ligament
- connects the liver to the anterior abdominal wall
2- Stomach is connected to:
A- inferior surface of the diaphragm by the gastrophrenic ligament
B- spleen by the gastrosplenic ligament
C- transverse colon by the gastrocolic ligament
Arterial Supply to the Abdominal Viscera
Through three main branches of the abdominal aorta:
1- ciliac trunk
Divides into:
a- hepatic artery
b- spleenic artery
c- gastric artery
2- superior mesenteric artery
3- inferior mesenteric artery
These vessels are SINGULAR vessels (only one)
Portal Vein
- main channel of the portal system of veins, which collect blood from the abdominal part of the
GI tract, the gall bladder, pancreas, and spleen and carries it to the liver
Esophagus
- MUSCULAR tube
- about 25cm long
- runs from the larynx to the stomach
- follows the curve of the vertebral column as it descends through the neck and the posterior
mediastrinum
- pierces the diaphragm, just to the left of the median plane (superior and inferior)
- enters the cardia region of the stomach at about the level of the 7th costal cartilage (at level of
about the 10th thoracic vertebrae)
- enclosed by an esophageal plexus of nerves
- covered anterior and laterally in the abdomen by peritoneum, but the esophagus is
retroperitoneal
Arterial Supply
Via:
- the gastric branch of the ciliac trunk
- inferior phrenic artery
Venous Drainage
- left gastric vein – which drains into the azygos vein
Innervation
Via:
- posterior gastric nerves (from the Vagus)
Stomach
Contains:
- a lesser curvature forming its concave border
- a greater curvature forming the large convex border
- a sharp indentation, about 2/3 of the way down the lesser curvature – angular notch of the
stomach
- this notch represents to point where the body of the stomach CHANGES into the
pyloric region of the stomach
Parts of the Stomach
- cardia – is all the way up on top near the opening of the esophagus
- fundis – dilated upper part that is in contact with the dome of the diaphragm
- body – between the fundis and the pyloric region
- pyloric region – below the angular notch, ends at the pyloric sphincter (a thickened band of
muscle controlling discharge of stomach contents into the duodenum)
- The stomach is covered with peritoneum, EXCEPT for the region where the esophagus ends
(the back of the cardia region) and along the curvatures where some vessels are located
The anterior surface of the stomach is in contact with:
- the diaphragm
- the left lobe of the liver
- anterior abdominal wall
The stomach bed (which stomach lies on when lying on your back) is formed by:
- the posterior wall of the omentum
- structures between that omentum (piece of mesentery) and the posterior abdominal wall
(diaphragm, transverse colon, pancreas, spleen, ciliac trunk and its three branches, as well as the
left kidney and the left adrenal gland)
Gastric arteries arise from ciliac trunk:
-Left and right gastric arteries and gastro omental arteries
Gastric veins parallel the arteries
The left and right gastric vein drain into the portal vein
The gastro-omental (aka. epiploic) vein drains into the spleenic vein, which joins the superior
mesenteric vein to form the portal vein
Nerves
Parasympathetic Nerves
- innervation is by vagal trunks
Sympathetic Nerves
- from T6 – T9, which join the ciliac plexus, and then are distributed along the gastric arteries
Small Intestine
Small intestine extends from the pylorus to the iliac secal valve
Three Parts:
1- Duodenum
- shortest, widest, and most FIXED part of the small intestine
- follows a “C” shaped course around the head of the pancreas
- begins at the pylorus, on the right side
- ends at the duodenojejunal junction on the left side
Divided into 4 parts:
A- Superior Part
- anteriolateral to the body of the 1st lumbar vertebrae
- 5 cm in length
B- Descending Part
- about 8-10 cm in length
- descends along the right side of L1, L2, L3
C- Horizontal Part
- about 7-8 cm in length
- crosses in front of the body of L3
D- Ascending Part
- about 5 cm
- begins on the left side of L3 and rises to the superior border of L2
First 2cm of duodenum – duodenal cap
- it is covered with mesentery
- most MOBILE part of the duodenum
- fixed, but a little bit of movement – where chyme is being pushed into stomach
The rest of the duodenum - retroperitoneal
Bile duct and the pancreatic duct enter the posterior medial wall of the duodenum and form the
hepatopancreatic duct
- these ducts usually UNITE to form the **heptopancreatic ampula** (swelling) and
enter the duodenum on it’s posterior medial wall.
The duodenum joins the jejunum at the duodenojejunal flexure
- this region is supported by a fibromuscular band called the suspensory muscle of the
duodenum (Ligament of Treitz)
- muscle
- contains contractile fibers
- when they contract, they facilitate movement of material through the
lumen
-The duodenum is supplied by superior and inferior pancreatoduodenal arteries
-Duodenal veins drain the duodenum and enter the portal vein
-Duodenum receives BOTH parasympathetic (vegas) and sympathetic nerve fibers (these come
off a plexus that run along the duodeno arteries)
-**95% of duodenal ulcers occurs in the 1st part of the duodenum (superior part that receives the
chyme and is mostly acidic-why most ulcers occur here)
- if the ulcer perforates the duodenal wall, it’s contents will enter the peritoneal space and
it could cause peritonitis**
- due to the proximity of the pancreas and the liver to the 1st part of the duodenum, ulcers
could affect those organs as well**
**If there is erosion of the gastroduodenal artery, which is posterior to the 1st part of the
duodenum, there will be significant hemorrhaging into the peritoneal cavity
2, 3- Jejunum & Ileum
- begins at the duodenojejunal flexure
- ends at the iliosecal valve
Together, the jejunum and the ileum, are approximately 6-7 meters long
About 40% is jejunum
Ileum is the balance – longer
Most of the jejunum is in the umbilical region
Most of the ileum is in the suprapubic and right inguinal regions
There is NO clear demarcation between the jejunum and the ileum
Mesentery attaches most of the small intestine to the posterior abdominal wall
Superior mesenteric artery supplies the jejunum and the ileum
Veins of the same name (superior mesenteric vein) drain the jejunum and the ileum
Sympathetic Nerves to the Jejunum and the Ileum
- from T5 – T9
Parasympathetic Nerves to the Jejunum and the Ileum
- from vagal trunks
Sympathetic stimulation:
- DECREASE motility
- DECREASE secretions
- Vasoconstrictor
Parasympathetic stimulation is the OPPOSITE:
- INCREASE motility
- INCREASE secretions
- Vasodilator
The intestine is NOT sensitive to most pain stimuli
- including cutting and burning
- But it IS sensitive to distension, which is perceived as pain
Occlusion of the vasorecta of the SMA results in ischemia to the affected intestine. IF the
ischemia is sever any where in the body, necrosis could occur. Ilius is severe pain usually
accompanied by nausea, vomiting and dehydration and if Dx early enough, then obstructed
vessels can be cleared. Dx by arteriogram
Large Intestine
Consists of:
- cecum
- vermiform (appendix)
- colon
- rectum
- anal canal
- Easy to distinguish from small intestine because the large intestine has THREE thick bands of
muscle called the tenae choli
- Has segments between the tenae choli - haustra
The large intestine has small pouches of omentum filled with fat called omental (epiploic)
appendages
Cecum
-separated by the ilium via the iliosecal valve. The ilium actually invaginates into the cecum at
this point.
- first part of the large intestine
- continuous with the ascending colon
- located in the right upper quadrant
- rests in the iliac fossa (indentation on the ileum)
- surrounded by peritoneum - But has NO mesentery
Appendix (Vermiform Appendix)
- worm-shaped blind (goes no place) tube that joins the cecum inferior to the iliosecal junction
- has a short triangular mesentery called the meso-appendix – that suspends the appendix from
the mesentery of the ileum
- is usually retrocecal
****The base of the appendix lies just underneath to McBernie’s Point
- located 1/3 the way along an oblique line that joins the right anterior superior iliac
spine to the umbilicus
The Cecum is supplied by:
- the iliocolic artery – branch of the SMA (superior mesenteric artery)
The Appendix is supplied by:
- the appendicular artery – branch of the iliocolic artery
Acute Inflammation of the Appendix
Results in:
- acute abdominal pain
- digital pressure over McBernie’s Point usually indicates the region of the MOST tenderness
Appendicitis
- caused by the obstruction of the appendix by fecal matter, preventing the appendix’s secretions
from draining
 appendix swells and stretches
- most notably – stretches the visceral peritoneum
Pain (associated with acute appendicitis)
- starts as dull pain in the periumbilical region because the afferent pain fibers enter the spinal
cord at the level of T10
- later on, pain develops in the right lower quadrant – caused by irritation of the peritoneum
Colon
Ascending Colon
- passes superiorly from the cecum on the right side to the liver, where it turns to the left at the
right colic flexure [hepatic flexure] (where the ascending colon becomes transverse)
- retroperitoneal
- supplied by branches of the SMA
Transverse Colon
- LARGEST and MOST mobile part of the large intestine
- crosses from right to left across the abdomen
- at the left colic flexure [splenic flexure], it turns inferiorly to become the descending colon
- the left colic flexure lies on the inferior part of the left kidney
- it is attached to the diaphragm by the phrenocolic ligament
The Transverse Mesocolon
- mesentery associated with the transverse colon
- most mobile part
- position varies - usually hangs down the to level of the umbilicus
- arterial supply – from branch of the SMA
- receives innervations from both divisions of the ANS
Descending Colon
- passes retroperitoneally from the left colic flexure into the left iliac fossa, where it’s continuous
with the sigmoid colon
- descends right next to the border of the left kidney
- peritoneum on its anterior and lateral surfaces bind it to the posterior abdominal wall
Sigmoid Colon
- “S” shaped loop
- links the descending colon to the rectum
- descends to the third segment of the sacrum, where it joins the rectum
- the termination of the last of the tenae cholae, marks the beginning of the rectum
- the Rectosigmoid Junction - about 15cm from the anus
- this region of the gut (sigmoid colon) is supplied by the IMA (inferior mesentery artery)
- has BOTH sympathetic and parasympathetic nerve supply
Spleen
- the LARGEST lymphatic organ
- located in the right upper quadrant
- its diaphragmatic surface is convexly curved to fit into the dome of the diaphragm
- contains a large volume of blood that is periodically expelled by muscle contraction into the
circulation
- attached to the stomach by the gastrospleenic ligament
- attached to the left kidney by the splenorenal ligament
- EXCEPT at the hilum of the spleen, where the spleenic artery enter and the spleenic vein
leaves, the spleen I enclosed in peritoneum
- the hilum of the spleen is right next to the tail of the pancreas
The Spleenic Artery
- LARGEST branch of the ciliac trunk
- it divides into five branches as it enters the hilum of the spleen
- the spleenic vein unites with the superior mesenteric vein in forming the portal vein
- the spleen is often injured and bleeds profusely because its capsule is very thin and its
parenchyma (tissue it’s composed of) is very soft and pulpy
- CAN’T sew it back together
 removed (spleenectomy)
Pancreas
- an elongated digestive and endocrine organ
- lies transversely along the posterior abdominal wall behind the stomach
- produces an endocrine secretion, pancreatic juice, that enters the duodenum via the pancreatic
ducts
- produces hormones, exocrine secretions, that enter the vascular system DIRECTLY (no ducts)
Head of the Pancreas
- located in the curve of the duodenum
- has a prolongated region, uncinate process
- lies behind the superior mesenteric vessels
- lies on the IVC (inferior vena cava)
- in contact with the right renal artery and vein and the left renal vein
- Common Bile Duct
- lies in a groove on the posterior superior surface on the head of the pancreas
Neck of the Pancreas
- right next to the pyloric sphincter
Body of the Pancreas
- extends to the left across the aorta and the 2nd lumbar vertebrae
Anterior Surface of the Pancreas
- covered by peritoneum
- forms part of the bed of the stomach
Posterior Surface of the Pancreas
- has NO peritoneum
- is in contact with:
- the aorta
- SMA (superior mesenteric artery)
- left kidney
- adrenal gland
- renal vessels
Tail of the Pancreas
- passes between the layers of the spleenorenal ligament
- contacts the hilum of the spleen
Pancreatic Duct
- begins in the tail of the pancreas and runs through the gland, where it turns (downward)
inferiorly next to the CBD (common bile duct)
-Common Bile Duct + Pancreatic Duct  Hepatopancreatic Ampula. This ampula opens into
the duodenum
-Before it unites to CBD - Sphincter at end of the pancreatic duct – pancreatic duct sphincter
-Distal to the hepatopancreatic ampulla – is the Sphincter of Oddi (hepatopancreatic duct
sphincter)
Hepatopancreatic ampulla – enlargement right where CBD and PD unite
Prior to the duodenum, you have the Sphincter of Oddi
Sphincter of Oddi – has to be relaxed for anything in those ducts to get into the duodenum
*In about 9% of the population, there is an excessive pancreatic duct that arises from the
unsinate (a little extension on the head of the pancreas) process and enters the duodenum alone*
Pancreas has a RICH arterial supply
Via:
- the splenic artery (largest branch of the ciliac trunk)
- branches of the gastroduodenal artery
Surface Anatomy of the Spleen and Pancreas
Spleen
Spleen lies on the left side between the 9th and 11th ribs
The long axis of the spleen rests on the left colic flexure
Pancreas
The tail of the pancreas touches the hilum of the spleen
The body of the pancreas lies at the level of the disc between T12 and L1
Liver
- LARGEST gland in the body
- mainly in right upper quadrant
- protected by some degree by thoracic cage
- pyramidal in shape
- base to the right
- apex to the left
- extends inferiorly to the right costal margin
- easily palpated when the patient inspires due to the inferior movement of the diaphragm
(diaphragm pushes it down)
- in addition to many metabolic activities:
- stores glycogen
- S & S (synthesizes and secretes bile)
- bile – directed through hepatic duct  cystic duct  gall bladder (concentrated
by reabsorption of water)
- diaphragmatic surface of the liver – smooth and dome shaped
- conforms to the concavity of the dome of the diaphragm
- separated from the diaphragm by the subphrenic recess (below the diaphragm)
- which is a reflection of the peritoneum
- potentional area for spread of infection
- covered by peritoneum, EXCEPT posteriorly in the bare area, where it is in direct contact with
the diaphragm
Because of weight of liver, reinforced by a series of ligaments
Ligaments
Bare area (not covered with peritoneum and in contact with diaphragm)
- surrounded by the anterior (upper) and posterior (lower) coronary ligaments
The coronary ligaments (upper and lower)
- merge to form the right triangular ligament
The anterior layer of the coronary ligament is continuous on the left with the right layer of the
falciform ligament
The posterior layer of the coronary ligament is continuous with the right lesser omentum
The falciform ligament and the lesser omentum meet to form the left triangular ligament
Helps segment liver into lobes and support weight of the liver
Visceral Surface of the Liver
- covered with peritoneum, EXCEPT at the location of the gallbladder (gallbladder fossa) and at
the porta hepatis (doorway – analogous to hilum),
- related to the right side of the stomach, the superior part of the duodenum, the lesser omentum,
the right colic flexure, the right kidney, and the right adrenal gland
Hepatorenal Recess
- region between the visceral surface of the right lobe of the liver and the right kidney
Lobes of the Liver
Divided into functionally independent right and left lobes (analogous to lobes of the lung)
Each lobe has its own:
- blood supply from hepatic artery and portal vein
- venous drainage
- billiary drainage
The Right Lobe
- demarcated from the left by the gallbladder fossa and by the indentation for the IVC on the
visceral surface of the liver
The Left Lobe
- Further divided into:
- caudate lobe
- quadrate lobe
The Lesser Omentum
- enclosing the portal triad, at the porta hepatic, attaches to the lesser curvature of the stomach
**Portal Triad
Include:
1- Portal Vein
2- Bile Duct
3- Hepatic Artery
Part of the lesser omentum between the liver and the stomach – hepatogastric ligament
Part of the lesser omentum between the liver and the duodenum – hepatoduodenal ligament
Liver receives blood from two sources:
1- 30% from the hepatic artery
2- 70% from the portal vein
Hepatic Artery
- brings oxygen rich blood to the cells of the liver
- comes off the abdominal aorta
Portal Vein
- carries oxygen deficient blood from the liver to the GI tract
At the porta hepatis, the hepatic artery and portal vein EACH bifurcate, thereby sending a branch
to each lobe of the liver, right and left lobe
A horizontal plane through each lobe divides into 8 vascular segments
- hepatic veins drain the segments
- drain into the IVC, just inferior to the diaphragm
- attachment of these veins to the IVC helps to hold the liver in position
Nerves of the Liver
- derived from the hepatic plexus
- LARGEST plexus that arises from the ciliac plexus
- consists of both sympathetic and parasympathetic fibers
Bile
- continually synthesized and secreted by hepatocytes
- drain through a series of ducts into the right and left hepatic duct
- after leaving the porta hepatis, the right and left bile duct unite to form the
Common Bile Duct (CBD)
- the CBD descends to the superior part of the duodenum
- lies in a groove on the posterior surface of the head of the pancreas
- at the distal part of the bile duct is a thickened muscle band – choledochal sphincter
- when this sphincter contracts, bile is backed dup to the gallbladder, where it is
concentratede
- has extensive arterial supply primarily through:
- cystic artery
- right hepatic artery
- gastro duodeno artery
- pancreatoduodeno artery
- venous drainage is via veins with the same name
Gall Bladder
- lies in the gallbladder fossa on the visceral surface of the liver
- peritoneum holds it against the liver
- this tiny little sac
- described as having three parts:
1- Fundis
- widest part
- located at the tip of the right 9th costal cartilage in the midclavicular line
2- Body
- in contact with the visceral surface of the liver, transverse colon, and superior
part of the duodenum
3- Neck
- narrowest part
- directed toward the porta hepatis
- joins the cystic duct
- the mucosa over the neck of the gall bladder is shaped into a spiral fold, which is
called the spiral valve of the gallbladder
- this spiral valve helps to keep the cystic duct open
- the cystic artery supplies both the gallbladder and the cystic duct
Portal Vein
- main channel for the portal system of veins
- collects blood from the abdominal part of the GI tract and carries it to the liver
The Portal Venous System
- **communicates with the systemic venous system in the following way:
1- From the left gastric vein (portal) and esophageal vein, blood is directed toward the
azygos vein (systemic)
2- Between the rectal vein draining into the IVC (systemic) and the inferior mesenteric
(portal)
The Portal Systemic Anastomosis (connections) – is very important because:
- when the portal circulation is obstructed, which usually occurs when there is liver disease,
blood can still reach the right side of the heart via the IVC
- this system works ONLY because the portal veins and all of the branches have NO VALVES
- therefore, blood can flow in a reverse direction to the IVC if there is an obstruction
Kidneys
- retroperitoneal
- located on the posterior abdominal wall on either side of the vertebral column
- between T12 and L3 bilaterally
- right kidney is a little bit lower than the left kidney (because of right lobe of the liver being so
large)
- each kidney has an:
- anterior and posterior surface
- medial and lateral margin
- superior and inferior pole
- superiorly, each kidney is right next to the diaphragm and rib 12
- inferiorly, each kidney lies on the quadratis lumborum muscle (around L3, L4)
Subcostal vessels and the iliohypogastric and ilioinguinal nerves
- pass over the posterior surface of each kidney
Anterior to the right kidney:
- liver,
- duodenum
- ascending colon
Left kidney is right next to:
- stomach
- spleen
- pancreas
- descending colon
Medial surface of each kidney has a cleft (hilum)
- anything that enters or leaves the kidney passes
- renal vein is anterior to the artery
- artery is anterior to the renal pelvis (expanded end of the ureter)
Renal Fascia
- fibrous tissue that surrounds each kidney
- sends collagen fibers through the fat to hold vessels, ureters, and kidneys in position. (renal
ptosis- where the kidneys slip down and cause a kink in the ureters, stopping flow of urine)
- is separated from the parenchyma of the kidney itself by a layer of fat called the perirenal fat
- external to the fascia, is pararenal fat
- these layers of fat:
- protect the kidney
- allows a little bit of movement of kidney during ventilation
- Collagen fibers that arise from the fascia and pass through the pararenal fat to attach the
kidneys to the posterior abdominal wall, preventing:
- free mobility
 preventing a bend in the ureters
- renal fascia ascends to cover the suprarenal glands (adrenal glands)
- inferior to the kidney, the renal fascia is replaced by loose connective tissue
Ureters
- muscular ducts with narrow lumens that carry urine from the kidney to the bladder
- expanded end – renal pelvis
- abdominal part adheres to the parietal peritoneum and is retroperitoneal (right behind it)
- runs inferiomedially along the transverse processes of the lumbar vertebrae
- then cross the external iliac arteries just below the common iliac bifurcation
Adrenal Glands
- suprarenal (above the kidney)
- lie on the superiomedial border of each kidney
- each gland is enclosed in a fibrous capsule, which is then enclosed by the renal fascia
The Right Gland
- anterior to the diaphragm
- makes contact with the IVC and the liver
The Left Gland
- in contact with:
- the spleen
- stomach
- pancreas
- diaphragm
Endocrine gland are DUCTLESS glands
- dump product directly into vascular system
Medulla
- associated with catecholamines (NE and Epi)
Cortex
Three Zones
- each secrets a classification of hormomes
- glucorticoids, androgens, mineralocorticoids
Renal Arteries
- off the abdominal aorta, at about L1 and L2, each enters a hilum of a kidney , then divides into
many many branches supplying the kidney tissue
- the kidneys are drained by renal veins
- each renal vein drains into the IVC directly
The Adrenal Glands
- has a profuse blood supply from:
1- Superior Suprarenal Arteries
- comes off the inferior phrenic arteries
2- Middle Suprarenal Arteries
- comes directly off the abdominal aorta
3- Inferior Suprarenal Arteries
- come off the renal arteries
Each gland is drained by a large suprarenal vein
Blood Supply of Ureters
- from branches of:
- renal artery
- gonadal artery
Nerve Supply (to the adrenal glands, kidneys, ureters)
- from the renal plexus, containing both sympathetic and parasympathetic fibers to the kidneys,
adrenal, and ureters
Thoracic Diaphragm
- a musculotendonous partition between the thoracic and abdominal cavities
- principle muscle of inspiration
- forms the convex floor of the thorax
- forms the concave roof of the abdomen
- ONLY the domes of the diaphragm move during inspiration
- because the peripheral parts of the diaphragm are attached to the inferior thoracic cage
and to the lumbar vertebrae
- the right dome is HIGHER than the left dome (because of the liver)
- the level of the domes of the diaphragm varies, based on:
- the phase of ventilation
- posture
- size and distension of the abdominal viscera
Composed of:
- peripheral muscular part
- central apneustic part (central tendon of the diaphragm)
- muscle fibers radiate toward the central tendon
- divided into three sections:
1- sternal
- attached to the posterior area of the xiphoid
2- costal
- attached to the inferior 6 ribs
3- lumbar
- attached to the lumbar vertebrae
Central Tendon
- the tendon of ALL muscular fibers of the diaphragm
- fused with the inferior surface of the fibrous pericardium
- ** has NO bony attachments
Diaphragmatic Apertures (opening)
- openings that allow structures to pass between the thorax and the abdomen
Vena Caval Aperture (foramen)
- opening for the IVC
- is WITHIN the central tendon
- about the level of T8 and T9
- the outer surface of the IVC is adherent (attached) to the margin of the foramen
 when you inspire and the diaphragm descends, it widens (dilates) the IVC, which
facilitates venous return
Esophageal Hiatus
- aperture for the esophagus
- is IN THE RIGHT CRUST of the diaphragm at the level of T10
 the esophagus is constricted when the diaphragm contracts during inspiration
- vagal trunks and gastric vessels pass through the esophageal hiatus
Aortic Hiatus
- BEHIND the diaphragm
 blood flow through the aorta is not affected by diaphragmatic movements
- provides passageway (transmits) for thoracic duct and the azygos vein
Posterior Abdominal Wall
Composed of:
- muscles
- fat
- that are attached to the vertebrae, hip bones, and ribs
Also contains:
- fat
- nerves
- lymph nodes
- vessels
Three Paired Muscles on the Posterior Abdominal Wall
1- Psoas Major
- runs from the transverse processes of the lumbar vertebrae to the lesser trochanter on
the femur
- hip flexor
2- Quadratis Lumborum
- runs from the lumbar vertebrae to the iliac crest
- trunk extensor
3- Iliacis
- runs from the iliac fossa to the lesser trochanter
- hip flexor
Iliacis and Psoas has common distal attachment on lesser trochante (different proximal
attachments) – sometimes referred to Iliopsoas muscle
- the posterior abdominal wall is covered with a continuous layer of fascia that lies between the
parietal peritoneum and the muscle
- that fascia is named based on location
- Ex: Psoas Fascia – near Psoas muscle
Nerves of Posterior Abdominal Wall
- primarily subcostal nerves
- mainly from ventral rami of T12 that supply the muscles and the skin of the posterior
abdominal wall
- lumbar nerves – have sensory and motor fibers to the posterior abdominal wall
**Lumbar Plexus
- located within the psoas major muscle
- formed from the ventral rami of **L1, L2, L3, L4
Major Nerves include: (larger)
1- Obturator Nerve (L2, L3, L4)
- supplies the adductors of the thigh
2- Femoral Nerve (L2, L3, L4)
- supplies the iliacis muscle and the extensors of the thigh
3- Lumbosacral Trunk (L4, L5)
- descends into the pelvis to participate in the formation of the Sacral Plexus,
along with S1, S2, S3, S4
Autonomic Nerves
- sympathetic and parasympathetic
- come off ganglia that run along the abdominal aorta
- most of the arteries of the posterior abdominal wall come off the abdominal aorta
Branches of the Abdominal Aorta
Described as either being:
- Visceral or Parietal
- Paired or Unpaired
Ex: Unpaired Visceral – ciliac trunk (go to stomach and spleen), SMA and IMA (supply parts of
the small and large intestine)
Paired Visceral – renal arteries, suprarenal (adrenal), gonadal arteries
Paired Parietal – inferior phrenics and lumbars
Unpaired Parietal – median sacral artery (arises at the bifurcation of the aorta)
Venous Drainage of the Posterior Abdominal Wall
- via tributaries of the IVC (inferior vena cava) with the exception of the gonadal veins
There are three collateral roots in the circulatory tree available for venous return if IVC is
obstructed:
1- Anastomosis in the Abdomen and the Pelvis
- allowing venous blood to reach the superior and inferior epigastric veins
 blood then ascends through these vessels to the thoracoepigastric
veins
 from there into the SVC
2- Through tributaries of the IVC that anastomosis with the vertebral and azygos veins
- azygos vein loops around to drain into the SVC
3- Via the Lateral Thoracic
- connects the circumflex iliac veins to the axillary vein
 axillary vein back to the SVC
Lots of lymphatics around the IVC and aortic vessels. Lymph drains to cysternae cylii (a thin
walled sac at the inferior end of the thoracic duct, and located in front of bodies L1 and L2)
Thoracic duct
- receives all lymph from areas inferior to the diaphragm and returns lymph to the vascular
system at the junction of the left subclavian vein and left internal jugular vein. It also returns
lymph from the upper half of the body.
- 75% of lymph from the body returns via the thoracic duct