Muhammad Sohaib Shahid
(Lecturer & Course Co-ordinator MID)
University Institute of Radiological Sciences &
Medical Imaging Technology (UIRSMIT)
Large Intestine
 The large intestine extends from the ileum to the anus. It is divided into the
cecum, appendix, ascending colon, transverse colon, descending colon, and
sigmoid colon. The rectum and anal canal are considered in the sections on
the pelvis and perineum. The primary function of the large intestine is the
absorption of water and electrolytes and the storage of undigested material
until it can be expelled from the body as feces.
 Cecum
 Location and Description
 The cecum is that part of the large intestine that lies below the level of the
junction of the ileum with the large intestine . It is a blind-ended pouch that is
situated in the right iliac fossa. It is about 2.5 in. (6 cm) long and is completely
covered with peritoneum. It possesses a considerable amount of mobility,
although it does not have a mesentery. Attached to its posteromedial surface is
the appendix. The presence of peritoneal folds in the vicinity of the cecum
creates the superior ileocecal, the inferior ileocecal, and the retrocecal recesses
.
 As in the colon, the longitudinal muscle is restricted to three flat bands, the
teniae coli, which converge on the base of the appendix and provide for it a
complete longitudinal muscle coat. The cecum is often distended with gas and
can then be palpated through the anterior abdominal wall in the living
patient.
 The terminal part of the ileum enters the large intestine at




the junction of the cecum with the ascending colon. The
opening is provided with two folds, or lips, which form
the so-called ileocecal valve . The appendix communicates
with the cavity of the cecum through an opening located
below and behind the ileocecal opening.
Relations
Anteriorly: Coils of small intestine, sometimes part of
the greater omentum, and the anterior abdominal wall in
the right iliac region
Posteriorly: The psoas and the iliacus muscles, the
femoral nerve, and the lateral cutaneous nerve of the
thigh . The appendix is commonly found behind the
cecum.
Medially: The appendix arises from the cecum on its
medial side
Blood Supply
 Arteries
 Anterior and posterior cecal arteries form the ileocolic






artery, a branch of the superior mesenteric artery .
Veins
The veins correspond to the arteries and drain into the
superior mesenteric vein.
Lymph Drainage
The lymph vessels pass through several mesenteric nodes
and finally reach the superior mesenteric nodes.
Nerve Supply
Branches from the sympathetic and parasympathetic
(vagus) nerves form the superior mesenteric plexus.
Ileocecal Valve
 A rudimentary structure, the ileocecal valve consists of
two horizontal folds of mucous membrane that project
around the orifice of the ileum. The valve plays little or
no part in the prevention of reflux of cecal contents into
the ileum. The circular muscle of the lower end of the
ileum (called the ileocecal sphincter by physiologists)
serves as a sphincter and controls the flow of contents
from the ileum into the colon. The smooth muscle tone
is reflexly increased when the cecum is distended; the
hormone gastrin, which is produced by the stomach,
causes relaxation of the muscle tone.
Appendix
 Location and Description
 The appendix is a narrow, muscular tube containing a large amount
of lymphoid tissue. It varies in length from 3 to 5 in. (8 to 13 cm).
The base is attached to the posteromedial surface of the cecum
about 1 in. (2.5 cm) below the ileocecal junction . The remainder of
the appendix is free. It has a complete peritoneal covering, which is
attached to the mesentery of the small intestine by a short
mesentery of its own, the mesoappendix. The mesoappendix
contains the appendicular vessels and nerves.
 The appendix lies in the right iliac fossa, and in relation to the
anterior abdominal wall its base is situated one third of the way up
the line joining the right anterior superior iliac spine to the
umbilicus (McBurney's point). Inside the abdomen, the base of the
appendix is easily found by identifying the teniae coli of the cecum
and tracing them to the base of the appendix, where they converge
to form a continuous longitudinal muscle coat
Common Positions of the Tip of
the Appendix
 The tip of the appendix is subject to a considerable range
of movement and may be found in the following
positions:
(a)hanging down into the pelvis against the right pelvic
wall,
(b) coiled up behind the cecum,
(c) projecting upward along the lateral side of the cecum,
(d) in front of or behind the terminal part of the ileum.
 The first and second positions are the most common sites.
Blood Supply
 Arteries
The appendicular artery is a branch of the posterior cecal artery.
 Veins
The appendicular vein drains into the posterior cecal vein.
 Lymph Drainage
The lymph vessels drain into one or two nodes lying in the
mesoappendix and then eventually into the superior mesenteric
nodes.
 Nerve Supply
The appendix is supplied by the sympathetic and parasympathetic
(vagus) nerves from the superior mesenteric plexus. Afferent nerve
fibers concerned with the conduction of visceral pain from the
appendix accompany the sympathetic nerves and enter the spinal
cord at the level of the 10th thoracic segment.
Ascending Colon
 Location and Description
 The ascending colon is about 5 in. (13 cm) long and lies in the
right lower quadrant . It extends upward from the cecum to
the inferior surface of the right lobe of the liver, where it turns
to the left, forming the right colic flexure, and becomes
continuous with the transverse colon. The peritoneum covers
the front and the sides of the ascending colon, binding it to
the posterior abdominal wall.
 Relations
 Anteriorly: Coils of small intestine, the greater omentum,
and the anterior abdominal wall
 Posteriorly: The iliacus, the iliac crest, the quadratus
lumborum, the origin of the transversus abdominis muscle,
and the lower pole of the right kidney. The iliohypogastric
and the ilioinguinal nerves cross behind it
Blood Supply
 Arteries
 The ileocolic and right colic branches of the superior






mesenteric artery supply this area.
Veins
The veins correspond to the arteries and drain into
superior mesenteric vein.
Lymph Drainage
The lymph vessels drain into lymph nodes lying along
course of the colic blood vessels and ultimately reach
superior mesenteric nodes.
Nerve Supply
Sympathetic and parasympathetic (vagus) nerves from
superior mesenteric plexus supply this area of the colon.
the
the
the
the
Transverse Colon
 Location and Description
 The transverse colon is about 15 in. (38 cm) long and extends across the




abdomen, occupying the umbilical region. It begins at the right colic
flexure below the right lobe of the liver and hangs downward, suspended
by the transverse mesocolon from the pancreas. It then ascends to the left
colic flexure below the spleen. The left colic flexure is higher than the
right colic flexure and is suspended from the diaphragm by the
phrenicocolic ligament
The transverse mesocolon, or mesentery of the transverse colon,
suspends the transverse colon from the anterior border of the pancreas .
The mesentery is attached to the superior border of the transverse colon,
and the posterior layers of the greater omentum are attached to the
inferior border . Because of the length of the transverse mesocolon, the
position of the transverse colon is extremely variable and may sometimes
reach down as far as the pelvis.
Relations
Anteriorly: The greater omentum and the anterior abdominal wall
(umbilical and hypogastric regions)
Posteriorly: The second part of the duodenum, the head of the pancreas,
and the coils of the jejunum and ileum
Blood Supply
 Arteries
The proximal two thirds are supplied by the middle colic artery, a
branch of the superior mesenteric artery . The distal third is
supplied by the left colic artery, a branch of the inferior mesenteric
artery .
 Veins
The veins correspond to the arteries and drain into the superior
and inferior mesenteric veins.
 Lymph Drainage
The proximal two thirds drain into the colic nodes and then into
the superior mesenteric nodes; the distal third drains into the colic
nodes and then into the inferior mesenteric nodes.
 Nerve Supply
The proximal two thirds are innervated by sympathetic and vagal
nerves through the superior mesenteric plexus; the distal third is
innervated by sympathetic and parasympathetic pelvic splanchnic
nerves through the inferior mesenteric plexus.
Descending Colon
 Location and Description
 The descending colon is about 10 in. (25 cm) long and lies in the
left upper and lower quadrants. It extends downward from the
left colic flexure, to the pelvic brim, where it becomes
continuous with the sigmoid colon. The peritoneum covers the
front and the sides and binds it to the posterior abdominal wall.
 Relations
 Anteriorly: Coils of small intestine, the greater omentum, and
the anterior abdominal wall
 Posteriorly: The lateral border of the left kidney, the origin of
the transversus abdominis muscle, the quadratus lumborum,
the iliac crest, the iliacus, and the left psoas. The iliohypogastric
and the ilioinguinal nerves, the lateral cutaneous nerve of the
thigh, and the femoral nerve also lie posteriorly.
 Blood Supply
 Arteries
The left colic and the sigmoid branches of the inferior
mesenteric artery supply this area.
 Veins
The veins correspond to the arteries and drain into the
inferior mesenteric vein.
 Lymph Drainage
Lymph drains into the colic lymph nodes and the inferior
mesenteric nodes around the origin of the inferior
mesenteric artery.
 Nerve Supply
The nerve supply is the sympathetic and parasympathetic
pelvic splanchnic nerves through the inferior mesenteric
plexus.
Differences Between the Small and Large
Intestine
 External Differences
 The small intestine (with the exception of the duodenum) is





mobile, whereas the ascending and descending parts of the colon
are fixed.
The caliber of the full small intestine is smaller than that of the
filled large intestine.
The small intestine (with the exception of the duodenum) has a
mesentery that passes downward across the midline into the right
iliac fossa.
The longitudinal muscle of the small intestine forms a
continuous layer around the gut. In the large intestine (with the
exception of the appendix) the longitudinal muscle is collected
into three bands, the teniae coli.
The small intestine has no fatty tags attached to its wall. The large
intestine has fatty tags, called the appendices epiploicae.
The wall of the small intestine is smooth, whereas that of the large
intestine is sacculated.
Internal Differences
 The mucous membrane of the small intestine has
permanent folds, called plicae circulares, which are
absent in the large intestine.
 The mucous membrane of the small intestine has villi,
which are absent in the large intestine.
 Aggregations of lymphoid tissue called Peyer's
patches are found in the mucous membrane of the
small intestine; these are absent in the large intestine.
Pancreas
 Location and Description
 The pancreas is both an exocrine and an endocrine gland.
The exocrine portion of the gland produces a secretion that
contains enzymes capable of hydrolyzing proteins, fats, and
carbohydrates. The endocrine portion of the gland, the
pancreatic islets (islets of Langerhans), produces the
hormones insulin and glucagon, which play a key role in
carbohydrate metabolism.
 The pancreas is an elongated structure that lies in the
epigastrium and the left upper quadrant. It is soft and
lobulated and situated on the posterior abdominal wall
behind the peritoneum. It crosses the transpyloric plane.
The pancreas is divided into a head, neck, body, and tail .
 The head of the pancreas is disc shaped and lies within the
concavity of the duodenum . A part of the head extends to
the left behind the superior mesenteric vessels and is called
the uncinate process.
 The neck is the constricted portion of the pancreas and
connects the head to the body. It lies in front of the beginning
of the portal vein and the origin of the superior mesenteric
artery from the aorta
 The body runs upward and to the left across the midline . It is
somewhat triangular in cross section.
 The tail passes forward in the splenicorenal ligament and
comes in contact with the hilum of the spleen .
 Relations
 Anteriorly: From right to left: the transverse colon and the
attachment of the transverse mesocolon, the lesser sac, and
the stomach
 Posteriorly: From right to left: the bile duct, the portal and
splenic veins, the inferior vena cava, the aorta, the origin of the
superior mesenteric artery, the left psoas muscle, the left
suprarenal gland, the left kidney, and the hilum of the spleen
Pancreatic Ducts
 The main duct of the pancreas begins in the tail and
runs the length of the gland, receiving numerous
tributaries on the way . It opens into the second part of
the duodenum at about its middle with the bile duct on
the major duodenal papilla. Sometimes the main duct
drains separately into the duodenum.
 The accessory duct of the pancreas, when present,
drains the upper part of the head and then opens into
the duodenum a short distance above the main duct on
the minor duodenal papilla . The accessory duct
frequently communicates with the main duct.
Blood Supply
 Arteries
The splenic and the superior and inferior
pancreaticoduodenal arteries supply the pancreas.
 Veins
The corresponding veins drain into the portal system.
 Lymph Drainage
Lymph nodes are situated along the arteries that
supply the gland. The efferent vessels ultimately drain
into the celiac and superior mesenteric lymph nodes.
 Nerve Supply
Sympathetic and parasympathetic (vagal) nerve fibers
supply the area.
Spleen
 Location and Description
 The spleen is reddish and is the largest single mass of lymphoid
tissue in the body. It is oval shaped and has a notched anterior
border. It lies just beneath the left half of the diaphragm close to
the 9th, 10th, and 11th ribs. The long axis lies along the shaft of the
10th rib, and its lower pole extends forward only as far as the
midaxillary line and cannot be palpated on clinical examination .
 The spleen is surrounded by peritoneum , which passes from it at
the hilum as the gastrosplenic omentum (ligament) to the greater
curvature of the stomach (carrying the short gastric and left
gastroepiploic vessels). The peritoneum also passes to the left
kidney as the splenicorenal ligament (carrying the splenic vessels
and the tail of the pancreas).
Relations
 Anteriorly: The stomach, tail of the pancreas, and left
colic flexure. The left kidney lies along its medial border
 Posteriorly:
The diaphragm;
left pleura (left
costodiaphragmatic recess); left lung; and 9th, 10th, and
11th ribs (
 Blood Supply
 Arteries
 The large splenic artery is the largest branch of the celiac
artery. It has a tortuous course as it runs along the upper
border of the pancreas. The splenic artery then divides into
about six branches, which enter the spleen at the hilum.
 Veins
The splenic vein leaves the hilum and runs behind the
tail and the body of the pancreas. Behind the neck of
the pancreas, the splenic vein joins the superior
mesenteric vein to form the portal vein.
 Lymph Drainage
The lymph vessels emerge from the hilum and pass
through a few lymph nodes along the course of the
splenic artery and then drain into the celiac nodes.
 Nerve Supply
The nerves accompany the splenic artery and are
derived from the celiac plexus.
Supernumerary Spleen
 In 10% of people, one or more supernumerary spleens
may be present, either in the gastrosplenic omentum
or in the splenicorenal ligament. Their clinical
importance is that they may hypertrophy after removal
of the major spleen and be responsible for a recurrence
of symptoms of the disease for which splenectomy was
initially performed.
Kidneys
Introduction:
 The two kidneys function to excrete most of the
waste products of metabolism. They play a major
role in controlling the water and electrolyte balance
within the body and in maintaining the acid-base
balance of the blood. The waste products leave the
kidneys as urine, which passes down the ureters to
the urinary bladder, located within the pelvis. The
urine leaves the body in the urethra.
Anatomy
 The kidneys are reddish brown and lie behind the
peritoneum high up on the posterior abdominal
wall on either side of the vertebral column; they are
largely under cover of the costal margin .
 The right kidney lies slightly lower than the left
kidney because of the large size of the right lobe of
the liver. With contraction of the diaphragm during
respiration, both kidneys move downward in a
vertical direction by as much as 1 in. (2.5 cm).
 On the medial concave border of each kidney is a
vertical slit that is bounded by thick lips of renal
substance and is called the hilum .
 The hilum extends into a large cavity called the renal
sinus.
 The hilum transmits, from the front backward, the
renal vein, two branches of the renal artery and the
ureter. (VAU). Lymph vessels and sympathetic fibers
also pass through the hilum.
Renal Structure
 Each kidney has a dark brown outer cortex and a light brown
inner medulla.
 The medulla is composed of about a dozen renal pyramids, each
having its base oriented toward the cortex and its apex, the renal
papilla, projecting medially .
 The cortex extends into the medulla between adjacent pyramids
as the renal columns. Extending from the bases of the renal
pyramids into the cortex are striations known as medullary rays.
 The renal sinus, which is the space within the hilum, contains
the upper expanded end of the ureter, the renal pelvis. This
divides into two or three major calyces, each of which divides
into two or three minor calyces . Each minor calyx is indented by
the apex of the renal pyramid, the renal papilla.
Coverings





The kidneys have the following coverings :
Fibrous capsule: This surrounds the kidney and is closely
applied to its outer surface.
Perirenal fat: This covers the fibrous capsule.
Renal fascia: This is a condensation of connective tissue that
lies outside the perirenal fat and encloses the kidneys and
suprarenal glands; it is continuous laterally with the fascia
transversalis.
Pararenal fat: This lies external to the renal fascia and is
often in large quantity. It forms part of the retroperitoneal fat.
The perirenal fat, renal fascia, and pararenal fat support the
kidneys and hold them in position on the posterior abdominal
wall.
Important Relations, Right Kidney
 Anteriorly: The suprarenal gland, the liver, the
second part of the duodenum, and the right colic
flexure
 Posteriorly: The diaphragm; the
costodiaphragmatic recess of the pleura; the 12th
rib; and the psoas, quadratus lumborum, and
transversus abdominis muscles. The subcostal
(T12), iliohypogastric, and ilioinguinal nerves (L1)
run downward and laterally
Important Relations, Left Kidney
 Anteriorly: The suprarenal gland, the spleen, the
stomach, the pancreas, the left colic flexure, and coils of
jejunum
 Posteriorly: The diaphragm; the costodiaphragmatic
recess of the pleura; the 11th (the left kidney is higher)
and 12th ribs; and the psoas, quadratus lumborum, and
transversus abdominis muscles. The subcostal (T12),
iliohypogastric, and ilioinguinal nerves (L1) run
downward and laterally.
Blood Supply
Arteries
 The renal artery arises from the aorta at the level of the second
lumbar vertebra. Each renal artery usually divides into five
segmental arteries that enter the hilum of the kidney. They
are distributed to different segments or areas of the kidney.
Lobar arteries arise from each segmental artery, one for each
renal pyramid. Before entering the renal substance, each lobar
artery gives off two or three interlobar arteries . The
interlobar arteries run toward the cortex on each side of the
renal pyramid. At the junction of the cortex and the medulla,
the interlobar arteries give off the arcuate arteries, which
arch over the bases of the pyramids . The arcuate arteries give
off several interlobular arteries that ascend in the cortex.
The afferent glomerular arterioles arise as branches of the
interlobular arteries
Veins
 The renal vein emerges from the hilum in front of the
renal artery and drains into the inferior vena cava.
Lymph Drainage
 Lymph drains to the lateral aortic lymph nodes around
the origin of the renal artery.
Nerve Supply
 The nerve supply is the renal sympathetic plexus. The
afferent fibers that travel through the renal plexus
enter the spinal cord in the 10th, 11th, and 12th thoracic
nerves.
NEPHRON
 Each nephron is composed of a glomerular capsule,
glomerulus, proximal convoluted tubule, loop of Henle
and distal convoluted tubule.
 The renal corpuscle includes the glomerular capsule and
the glomerulus.
 The renal tubule is the part of the nephron that directs
the filtrate away from the glomerular capsule and includes
the proximal convoluted tubule, loop of Henle, distal
convoluted tubule and the collecting duct. The collecting
duct is not considered part of the nephron as many
nephrons drain into one collecting duct.
Component
Glomerular (Bowman)
capsule
Description
•The start of the nephron.
•It is a double-walled chamber
that looks as if the wall of the
nephron had been pushed in on
itself.
•The walls of the glomerular
capsule are thin, but only allow
water and small ions to pass
through.
•Filtrate (water and small
molecules) which is similar to
blood plasma passes into the
capsular space of the glomerular
capsule.
•The glomerular capsule
continues as the proximal
Function
Filtration
Component
Description
•A tiny capillary network that
lies within a glomerular capsule.
•The glomerulus receives blood
at high pressure from a tiny
branch of the renal artery, called
the afferent arteriole.
•The filtered blood (blood cells,
Glomerulus
proteins and large molecules)
leaves the glomerulus via the
efferent arteriole which goes
on to form a capillary
plexus around the PCT, before
draining into a tiny branch of the
renal vein.
Function
Filtration
Component
Proximal convoluted
tubule (PCT)
Description
•Originating from the glomerular
capsule the PCT is a highly twisted
and coiled tubule that descends
through the cortex.
•It is the part of the nephron
responsible for most of the
reabsorption of the filtrate.
•Water, glucose, amino acids and
salts are reabsorbed from the
PCT back into the blood.
•Drugs, toxins and solutes such as
bicarbonate, hydrogen and
potassium ions and urea are
secreted into the PCT.
•It continues as the loop of Henle.
Function
Reabsorption &
Secretion
Component
Loop of Henle
Description
•A tubule with a long hairpin turn,
its descending limb enters the
medulla, where it makes a 180
degree turn so that its ascending
limb enters the cortex.
•Salts are reabsorbed from the
loop of Henle into the medulla of
the kidney (making the medulla
very salty compared to the
filtrate).
•It ends in the cortex as the distal
convoluted tubule (DCT).
Function
Reabsorption
Component
Distal convoluted
tubule (DCT)
Description
•A highly coiled tubule located
in the cortex and surrounded
by capillaries.
•Salts such as sodium
are actively absorbed from the
DCT under the control of a
hormone called aldosterone.
•Hydrogen and potassium
ions are actively secreted into
the DCT to regulate ph.
•The rate of absorption and
secretion in the DCT are
controlled by hormones.
•It empties into the collecting
tubule (CT).
Function
Active Secretion
Component
Collecting tubule
(CT)
Description
Function
•They pass through the
medulla forming the pyramids
of the kidneys.
•Bicarbonate, potassium and
hydrogen ions, are secreted
into the CT to regulate ph.
•Water and salts
are reabsorbed from the urea
in the CT under the control of
Reabsorption,
two hormones (one of them Secretion & Transport
being anti-diuretic hormone
that increases the
CT permeability to water).
•Each CT opens into a minor
calyces at the apex of the renal
pyramid.
•From here urine flows via
 Filtration
FUNCTIONS
 Filtration at the glomerulus is under pressure as the
afferent arteriole is so close to the abdominal aorta. The
fluid that passes through the wall of the glomerular capsule
into the nephron is called the glomerular filtrate and is
similar in composition to plasma. Blood and protein cannot
pass into the filtrate but small waste molecules can.
 600 ml of blood will pass through the glomerulus each
minute, 125 ml of which will be absorbed into the nephron
as glomerular filtrate.
Reabsorption
 The tubule of the nephron functions to reabsorb most of the
glomerular filtrate. The cells of the tubule reabsorb vital
nutrients and water back into the blood, while retaining the
waste products that the body needs to eliminate. The plexus
formed by the efferent arteriole (from the glomerulus) passes
closely to the proximal convoluted tubule, allowing direct
transfer into the blood. In the loop of Henle the filtrate is
further concentrated. Water is absorbed by osmosis, being
transported down its concentration gradient.
 The amount of water reabsorbed is controlled by an antidiuretic hormone secreted by the posterior lobe of the
pituitary gland. The amount of salts reabsorbed is controlled by
aldosterone secreted by the cortex of the suprarenal glands.
These hormones are increased or decreased according to the
needs of the body
Active secretion
 During active secretion, wastes that were not initially
filtered out of the blood in the glomerular capsule such
as ammonia and certain drugs and toxins are removed
from the capillaries into the distal convoluted tubule.
Ureters
 The ureters are two tubes that drain urine from the renal
pelvis into the trigone of the bladder. They are 25 to 30
cm long with a diameter of approximately 3 mm.
 Each ureter descends on the surface of psoas major, behind
the ovarian or testicular vessels before entering the lesser
pelvis and running along its lateral wall, to finally turn
medially and enter the trigone of the bladder.
 The ureters have an outer fibrous layer, two muscular layers
and an inner mucous layer. Urine is passed down to the
bladder by peristaltic waves of the smooth muscle walls.
Clinical Considerations
Ureteric calculus
The lumen of the ureters become narrower in three
places; at the junction with the renal pelvis, where they
cross the brim of the lesser pelvis and where they pass
through the bladder wall. These restrictions can be the site
of impaction of a stone.
Suprarenal Glands
 Location and Description
 The two suprarenal glands are yellowish retroperitoneal organs that lie on the upper
poles of the kidneys. They are surrounded by renal fascia (but are separated from
the kidneys by the perirenal fat). Each gland has a yellow cortex and a dark brown
medulla.
 The cortex of the suprarenal glands secretes hormones that include mineral
corticoids, which are concerned with the control of fluid and electrolyte balance;
glucocorticoids, which are concerned with the control of the metabolism of
carbohydrates, fats, and proteins; and small amounts of sex hormones, which
probably play a role in the prepubertal development of the sex organs. The medulla
of the suprarenal glands secretes the catecholamines epinephrine and
norepinephrine.
 The right suprarenal gland is pyramid shaped and caps the upper pole of the right
kidney . It lies behind the right lobe of the liver and extends medially behind the
inferior vena cava. It rests posteriorly on the diaphragm.
 The left suprarenal gland is crescentic in shape and extends along the medial border
of the left kidney from the upper pole to the hilus . It lies behind the pancreas, the
lesser sac, and the stomach and rests posteriorly on the diaphragm.
 Blood Supply
 Arteries
The arteries supplying each gland are three in number:
inferior phrenic artery, aorta, and renal artery.
 Veins
A single vein emerges from the hilum of each gland and
drains into the inferior vena cava on the right and into the
renal vein on the left.
 Lymph Drainage
The lymph drains into the lateral aortic nodes.
 Nerve Supply
Preganglionic sympathetic fibers derived from the
splanchnic nerves supply the glands. Most of the nerves end
in the medulla of the gland.
 Cushing's Syndrome
Suprarenal cortical hyperplasia is the most common
cause of Cushing's syndrome, the clinical
manifestations of which include moon-shaped face,
truncal obesity, abnormal hairiness (hirsutism), and
hypertension; if the syndrome occurs later in life, it
may result from an adenoma or carcinoma of the
cortex.
 Addison's Disease
Adrenocortical insufficiency (Addison's disease),
which is characterized clinically by increased
pigmentation, muscular weakness, weight loss, and
hypotension, may be caused by tuberculous
destruction or bilateral atrophy of both cortices.
Nerves on the Posterior Abdominal Wall
 Lumbar Plexus
 The lumbar plexus, which is one of the main nervous pathways supplying the lower
limb, is formed in the psoas muscle from the anterior rami of the upper four
lumbar nerves . The anterior rami receive gray rami communicantes from the
sympathetic trunk, and the upper two give off white rami communicantes to the
sympathetic trunk. The branches of the plexus emerge from the lateral and medial
borders of the muscle and from its anterior surface.
 The iliohypogastric nerve, ilioinguinal nerve, lateral cutaneous nerve of the thigh,
and femoral nerve emerge from the lateral border of the psoas, in that order from
above downward . The iliohypogastric and ilioinguinal nerves (L1) enter the lateral
and anterior abdominal walls . The iliohypogastric nerve supplies the skin of the
lower part of the anterior abdominal wall, and the ilioinguinal nerve passes
through the inguinal canal to supply the skin of the groin and the scrotum or
labium majus. The lateral cutaneous nerve of the thigh crosses the iliac fossa in
front of the iliacus muscle and enters the thigh behind the lateral end of the
inguinal ligament . It supplies the skin over the lateral surface of the thigh. The
femoral nerve (L2, 3, and 4) is the largest branch of the lumbar plexus. It runs
downward and laterally between the psoas and the iliacus muscles and enters the
thigh behind the inguinal ligament and lateral to the femoral vessels and the
femoral sheath. In the abdomen it supplies the iliacus muscle.
 The obturator nerve and the fourth lumbar root of the
lumbosacral trunk emerge from the medial border of the
psoas at the brim of the pelvis. The obturator nerve (L2, 3,
and 4) crosses the pelvic brim in front of the sacroiliac joint
and behind the common iliac vessels. It leaves the pelvis by
passing through the obturator foramen into the thigh. (For a
description of its course in the pelvis and in the thigh . The
fourth lumbar root of the lumbosacral trunk takes part in the
formation of the sacral plexus. It descends anterior to the ala
of the sacrum and joins the first sacral nerve.
 The genitofemoral nerve (L1 and 2) emerges on the
anterior surface of the psoas. It runs downward in front of
the muscle and divides into a genital branch, which enters
the spermatic cord and supplies the cremaster muscle, and a
femoral branch, which supplies a small area of the skin of the
thigh. It is the nervous pathway involved in the cremasteric
reflex, in which stimulation of the skin of the thigh in the
male results in reflex contraction of the cremaster muscle
and the drawing upward of the testis within the scrotum.
Branches
Distribution
Iliohypogastric nerve External oblique, internal oblique, transversus abdominis muscles of
anterior abdominal wall; skin over lower anterior abdominal wall and
buttock
Ilioinguinal nerve
External oblique, internal oblique, transversus abdominis muscles of
anterior abdominal wall; skin of upper medial aspect of thigh; root of
penis and scrotum in the male; mons pubis and labia majora in the
female
Lateral cutaneous
nerve of the thigh
Skin of anterior and lateral surfaces of the thigh
Genitofemoral nerve
(L1, 2)
Cremaster muscle in scrotum in male; skin over anterior surface of
thigh; nervous pathway for cremasteric reflex
Femoral nerve (L2, 3, Iliacus, pectineus, sartorius, quadriceps femoris muscles, and
4)
intermediate cutaneous branches to the skin of the anterior surface of
the thigh and by saphenous branch to the skin of the medial side of
the leg and foot; articular branches to hip and knee joints
Obturator nerve (L2, 3, Gracilis, adductor brevis, adductor longus, obturator externus,
4)
pectineus, adductor magnus (adductor portion), and skin on medial
surface of thigh; articular branches to hip and knee joints
Segmental branches
Quadratus lumborum and psoas muscles
Peritoneum
 General Arrangement
 The peritoneum is a thin serous membrane that lines the walls




of the abdominal and pelvic cavities and clothes the viscera .
The peritoneum can be regarded as a balloon against which
organs are pressed from outside.
The parietal peritoneum lines the walls of the abdominal and
pelvic cavities, and the visceral peritoneum covers the
organs.
The potential space between the parietal and visceral layers,
which is in effect the inside space of the balloon, is called the
peritoneal cavity.
In males, this is a closed cavity, but in females, there is
communication with the exterior through the uterine tubes,
the uterus, and the vagina.
 The peritoneal cavity is the largest cavity in the body




and is divided into two parts:
The greater sac and the lesser sac .
The greater sac is the main compartment and extends
from the diaphragm down into the pelvis.
The lesser sac is smaller and lies behind the stomach.
The greater and lesser sacs are in free communication
with one another through an oval window called the
opening of the lesser sac, or the epiploic foramen .
The peritoneum secretes a small amount of serous
fluid, the peritoneal fluid, which lubricates the
surfaces of the peritoneum and allows free movement
between the viscera.
Intraperitoneal and Retroperitoneal Relationships
 An organ is said to be intraperitoneal when it is almost
totally covered with visceral peritoneum. The stomach,
jejunum, ileum, and spleen are good examples of
intraperitoneal organs.
 Retroperitoneal organs lie behind the peritoneum and
are only partially covered with visceral peritoneum. The
pancreas and the ascending and descending parts of
the colon are examples of retroperitoneal organs.
 No organ, however, is actually within the peritoneal
cavity. An intraperitoneal organ, such as the stomach,
appears to be surrounded by the peritoneal cavity, but it
is covered with visceral peritoneum and is attached to
other organs by omenta.
Peritoneal Ligaments
 Peritoneal
ligaments are two-layered folds of
peritoneum that connect solid viscera to the
abdominal walls. The liver, for example, is connected
to the diaphragm by the falciform ligament, the
coronary ligament, and the right and left
triangular ligaments
Omenta
 Omenta are two-layered folds of peritoneum that
connect the stomach to another viscus.
 The greater omentum connects the greater curvature of
the stomach to the transverse colon . It hangs down like
an apron in front of the coils of the small intestine and
is folded back on itself to be attached to the transverse
colon .
 The lesser omentum suspends the lesser curvature of
the stomach from the fissure of the ligamentum
venosum and the porta hepatis on the undersurface of
the liver . The gastrosplenic omentum (ligament)
connects the stomach to the hilum of the spleen
Mesenteries
 Mesenteries are two-layered folds of peritoneum connecting parts of







the intestines to the posterior abdominal wall, for example, the
mesentery of the small intestine, the transverse mesocolon, and the
sigmoid mesocolon .
The peritoneal ligaments, omenta, and mesenteries permit blood,
lymph vessels, and nerves to reach the viscera.
Duodenal Recesses
Close to the duodenojejunal junction, there may be four small
pocketlike pouches of peritoneum called the superior duodenal,
inferior duodenal, paraduodenal, and retroduodenal recesses .
Cecal Recesses
Folds of peritoneum close to the cecum produce three peritoneal
recesses called the superior ileocecal, the inferior ileocecal, and the
retrocecal recesses .
Intersigmoid Recess
The intersigmoid recess is situated at the apex of the inverted, Vshaped root of the sigmoid mesocolon ; its mouth opens downward.
 Paracolic Gutters
 The paracolic gutters lie on the lateral and medial sides of the ascending and
descending colons, respectively .
 The subphrenic spaces and the paracolic gutters are clinically important
because they may be sites for the collection and movement of infected
peritoneal fluid.
 Nerve Supply of the Peritoneum
 The parietal peritoneum is sensitive to pain, temperature, touch, and
pressure. The parietal peritoneum lining the anterior abdominal wall is
supplied by the lower six thoracic and first lumbar nerves”that is, the same
nerves that innervate the overlying muscles and skin. The central part of the
diaphragmatic peritoneum is supplied by the phrenic nerves; peripherally,
the diaphragmatic peritoneum is supplied by the lower six thoracic nerves.
The parietal peritoneum in the pelvis is mainly supplied by the obturator
nerve, a branch of the lumbar plexus.
 The visceral peritoneum is sensitive only to stretch and tearing and is not
sensitive to touch, pressure, or temperature. It is supplied by autonomic
afferent nerves that supply the viscera or are traveling in the mesenteries.
Overdistention of a viscus leads to the sensation of pain. The mesenteries of
the small and large intestines are sensitive to mechanical stretching.
Functions of the Peritoneum
 The peritoneal fluid, which is pale yellow and somewhat viscid, contains leukocytes. It is
secreted by the peritoneum and ensures that the mobile viscera glide easily on one
another. As a result of the movements of the diaphragm and the abdominal muscles,
together with the peristaltic movements of the intestinal tract, the peritoneal fluid is not
static. Experimental evidence has shown that particulate matter introduced into the
lower part of the peritoneal cavity reaches the subphrenic peritoneal spaces rapidly,
whatever the position of the body. It seems that intraperitoneal movement of fluid
toward the diaphragm is continuous , and there it is quickly absorbed into the
subperitoneal lymphatic capillaries.
 This can be explained on the basis that the area of peritoneum is extensive in the region
of the diaphragm and the respiratory movements of the diaphragm aid lymph flow in the
lymph vessels.
 The peritoneal coverings of the intestine tend to stick together in the presence of
infection. The greater omentum, which is kept constantly on the move by the peristalsis
of the neighboring intestinal tract, may adhere to other peritoneal surfaces around a
focus of infection. In this manner, many of the intraperitoneal infections are sealed off
and remain localized.
 The peritoneal folds play an important part in suspending the various organs within the
peritoneal cavity and serve as a means of conveying the blood vessels, lymphatics, and
nerves to these organs.
 Large amounts of fat are stored in the peritoneal ligaments and mesenteries, and
especially large amounts can be found in the greater omentum.