Anatomy abdomen and pelvis

Question 1

Medical Imaging of the abdomen
Identify structures on the axial slice of an abdo CT

Answer 1

Must be able to identify:
● Liver
● Intestines
● Pancreas
● Spleen
● Kidneys
● Descending aorta
● Vertebral body
● Rectus muscle
● Diaphragm
● Inferior vena cava

Question 2

Which structures are retroperitoneal?

Answer 2

Pancreas, kidneys, aorta, IVC

Question 3

Where is the transpyloric plane?

Answer 3

Passes through the lower border of L1

Question 4

What structures lie in the transpyloric plane?

Answer 4

● Pylorus – free on mesentery
● Pancreas- head, neck and body
● Fundus of the gallbladder
● Conus medulla of the spinal cord
● SMA as it leaves the aorta
● Hila of both kidneys
● 9
th costal cartilages
● Liver, spleen

Question 5

The Aorta
Outline the course of the abdominal aorta

Answer 5

● Enters the abdomen through the aortic hiatus at the level of T12
● Left of the midline
● Bifurcation at L4 just below the umbilicus

Question 6

Describe the branches of the abdominal aorta

Answer 6

Unpaired
● Coeliac
● Superior mesenteric
● Inferior mesenteric

Paired
● Suprarenal
● Renal
● Gonadal
● Subcostal
● Inferior Phrenic
● Lumbar
● Common iliacs

Question 7

What is the relationship of the IVC to the aorta?

Answer 7

● IVC lies posterolateral to the right of the aorta
● It leaves the abdomen through the caval opening of the diaphragm at T8 after
draining from the lower limbs and other non-portal blood tributaries.
● These tributaries correspond to the paired vessels of the aorta.

Question 8

Name the branches of the coeliac trunk and what they supply

Answer 8

● Arises at T12
● Branches are left gastric, common hepatic and splenic
● Supplies the liver, stomach, spleen, oesophagus and superior part of the
duodenum and pancreas

Question 9

Describe the arterial blood supply of the small and large intestine

Answer 9

● Small intestine is supplied by the branches which arise from the superior
mesenteric artery
● The large intestine is supplied by both the superior mesenteric and the inferior
mesenteric artery
● SMA supplies the supplies the ascending and the proximal 2/3 of the transverse
colon
● IMA supplies the descending colon and the sigmoid & rectum

Question 10

Describe the course of the iliac arteries

Answer 10

● Common iliacs originate from the aorta at L3
● Follow the medial border of the psoas to the pelvic brim
● Divide at the level of L5/S1 into the internal and external iliacs
● Internal iliac artery enters the pelvis
● External iliac artery follows the iliopsoas and ends at the inguinal ligament, where
it becomes the femoral artery at the mid inguinal point

Question 11

Porto systemic anastomosis
Describe the portosystemic anastomoses

Answer 11

Portosystemic anastamosis is the collateral communication between the portal and the
systemic venous system. There are 4 main sites.

● Oesophageal - oesophageal veins drain into the azygous (systemic) or left
gastric (portal) veins.
● Rectal - inferior and middle rectal veins go into the IVC (systemic) and the
superficial rectal vein goes to the inferior mesenteric vain (portal)
● Umbilical - paraumbilical veins (portal) and epigastric veins on the anterior
abdominal wall (systemic)
● Retroperitoneal - visceral (portal) veins on the bare areas of organs and the
systemic veins on the posterior abdominal wall

Question 12

When do portosystemic anastomosis become clinically significant?

Answer 12

● When there is obstruction to portal flow from something i.e. liver disease that
leads to portal hypertension
● Blood is redirected to the lowe pressure venous system via shunting
● Porto-systemic shunting occurs because there are no valves in the portal system
● Over time, veins can become dilated and can cause major haemorrhage via
rupture - typically in ED this is seen in oesophageal variceal bleeding.

Question 13

The Liver
Anatomy of the Liver

Answer 13

Name the lobes (left and right, caudate, quadrate)
● Vascular stuff – IVC, hepatic artery, portal vein
● Biliary – common hepatic duct, gallbladder
● Ligaments – ligamentum teres, diaphragm

Question 14

What are the anatomical relations of the liver?

Answer 14

● Located in the right upper portion of the abdominal cavity
● Lies adjacent to the chest wall and ribs - makes it vulnerable during rib fractures
and one of the possible complications associated with low placement of a chest
tube
● Superiorly it abuts the right hemidiaphragm
● Inferiorly it contacts the right kidney, right adrenal gland, right colic flexure,
transverse colon, the first part of the duodenum and the stomach

Question 15

Describe the anatomy of the biliary tree

Answer 15

● Left and right hepatic ducts run into common hepatic duct
● Joined by cystic duct from the gallbladder to become the common bile duct which
joins with the pancreatic duct and both empty into the duodenum

Question 16

What is the blood supply of the liver?

Answer 16

● Hepatic artery
● Portal vein
● 3 hepatic veins

Question 17

The Pancreas
What are the anatomical relationships of the pancreas?

Answer 17

*Posteriorly – portal vein, right renal artery and vein, bile duct, superior mesenteric
vessels, aorta, L2 vertebrae, L kidney, L adrenal
● Medial – duodenum makes a C shape around the head
● Laterally the hilum of the spleen at the tail of the pancreas
● Anterior – stomach, peritoneum, lesser omentum, bowel

Question 18

What are the parts of the duodenum?

Answer 18

● 1st part (“superior”) - runs to the right, superiorly and posteriorly from the
pylorus, anterior to L1 vertebra
● 2nd part (“descending”)- covered by the peritoneum in front and crossed by the
transverse mesocolon, crosses downward and over the hilum of the right kidney
● 3rd part (“horizontal”) - curves forwards over the right psoas and over the IVC
and aorta to reach the left psoas
● 4th part (“ascending”) - ascends to the left of the aorta to lie on the left psoas and
sympathetic trunk. Reaches back up to the lower border of the pancreas

Question 19

What is the blood supply of the duodenum?

Answer 19

● 1st 2cm of the first part, blood from everywhere
● Hepatic artery, the gastroduodenal artery (usually the one that ulcerates and
bleeds) supraduodenal artery, right gastric and right gastroepiploic arteries
● The most of the rest is supplied via the coeliac trunk via the gastroduodenal
artery and SMA via the inferior pancreatic/duodenal arteries

Question 20

SPLEEN
Describe the anatomical relationships of the spleen

Answer 20

● Lies deep to and along the plane of the 9/10/11
th
ribs in the left upper quadrant of
the abdomen
● Inferiorly there is the left kidney and the splenic flexure of the colon
● Superiorly and laterally is the diaphragm
● Medially is the stomach and pancreas
● Deep is the splenic artery and veins

Question 21

The Renal Tract
Describe the relations of the right kidney

Answer 21

● Surrounded by perinephric fat
● Superior – right adrenal + liver + portal vein
● Superolaterally – right lobe of liver
● Medially – psoas and vertebrae
● Posteriorly – 12
th
rib + abdo muscles, deep back muscles
● Anteriorly – gallbladder + duodenum + ascending colon
● Anteromedially – right renal vein, IVC, pancreas

Question 22

Please outline the course of the ureters

Answer 22

● Originate at the renal hilum – approx. L1- L2
● Run inferiorly over the psoas
● Just medial to the tips of transverse process of lumbar vertebrae
● Cross the pelvic brim over the SI joint
● Travel anterior to the bifurcation of common iliac arteries
● Lie on the lateral wall of the pelvis
● Travel medially to the bladder at the ischial spines
● Short intramural path at VUJ

Question 23

What are the three narrowest points of the ureters?

Answer 23

● PUJ
● VUJ
● Pelvic brim

Question 24

What is the arterial blood supply of the ureter?

Answer 24

● Renal arteries supply the upper portion
● Gonadal vessels can supply some of the upper part
● Mid portion comes from branches of the abdominal aorta
● Inferiorly by branches of common iliacs
● Venous drainage is via the renal and gonadal vessels

Question 25

BLADDER
Please describe the motor innervation of the bladder
Innervation is via both autonomic and somatic arms of the nervous system

Answer 25

● Sympathetic fibres travel via the hypogastric nerve plexus to excite the internal
urethral sphincter and cause relaxation of the detrusor muscle. This promotes
urinary retention
● Parasympathetic fibres travel via the pelvic nerve and are the motor supply to the
detrusor. They also provide inhibitory signals to the internal urethral sphincter.
This promotes micturition.
● Somatic innervation is via the pudendal nerve. It innervates the external urethral
sphincter providing voluntary control over micturition

Question 26

Please describe the stretch reflex of the bladder

Answer 26

● Is a primitive spinal reflex arc
● Bladder fills with urine, and the bladder wall is stretched. Sensory nerves detect
the stretch and and transmit the information to the spinal cord
● Interneurons within the spinal cord relay the signal to the parasympathetic
efferent fibres (the pelvic nerve)
● Pelvic nerve acts to contract the detrusor muscle to stimulate micturition
● This reflex arc is overridden during the process of toilet training of children but
can be important to consider in spinal injuries (where descending inhibition
cannot reach the bladder) and in neurodegenerative diseases where the brain is
unable to generate inhibition

Question 27

What is the blood supply to the uterus?

Answer 27

● Uterine artery from the anterior division of the internal iliac artery
● Crosses above the ureter on its course to the uterus (bridge over water)
● Commonly anastomoses with the vaginal and ovarian arteries

Question 28

What are the potential spaces within the female pelvis where free fluid may
accumulate?

Answer 28

● Rectouterine pouch
● Vesicouterine pouch

Question 29

What are the boundaries, relations and the significance of the recto-uterine
pouch?

Answer 29

● Inferior most extension of the peritoneal cavity
● Important because it is a potential space for fluid collection
● Between the anterior rectum and the posterior uterus
● Close to the cervix and the posterior fornix of the vagina
● Open superiorly to the peritoneum

Question 30

What are the contents of the spermatic cord?

Answer 30

● Ductus deferens
● Artery of the ductus deferens
● Testicular artery
● Testicular vein and pampiniform plexus
● Lymphatics
● Autonomic nerves (both sympathetic and parasympathetic)

Question 31

Using the model, identify the components that make up the male urogenital
system

Answer 31

Bladder, ureter, prostate gland, seminal gland, spermatic cord, testis, epididymis, penis

Question 32

What are the components of the male urethra?

Answer 32

● Intramural component – in the base of the bladder wall
● Prostatic component in the prostate
● Membranous component (short, narrow section surrounded by the external
sphincter)
● Spongy component (length of the corpus spongiosum)

Question 33

What is the innervation of the urethra in a male?

Answer 33

● Prostatic nerve plexus arising from the inferior hypogastric plexus to the first
three parts
● Then the dorsal nerve of the penis to the spongy part

Question 34

What is the lymphatic drainage of the male genitalia?

Answer 34

● Testicles – lymph drains back along the path of the testicular artery to para-aortic
nodes
● Skin from the scrotum and penis drains to inguinal nodes

Question 35

Inguinal Canal
What is the difference between a direct and indirect hernia?

Answer 35

Direct hernia is acquired - goes “directly” through the muscle
● Secondary to weakness in the anterior wall
● Traverses the medial third of the inguinal canal
● Exits superficial ring lateral to the cord
● Rarely enters the scrotum

Indirect hernia is a congenital condition
● Occurs due to a patent processus vaginalis (allows communication between the
peritoneum and the scrotum)
● Traverses the entire canal - from internal to external riung
● Travels inside the cord and into either the scrotum in males or the external labia
in females