Anatomy of the Abdomen 4

Question 1

What is lumbar lordosis?

Answer 1

Lumbar lordosis - is the inward curve of the lumbar, or lower, spine in the lower back. A small degree of lordosis (inward curvature) is normal, but excessive lordosis can result from underlying disease and conditions of the spine.

Question 2

What articulates with the sacrum?

Answer 2

The 5th lumbar vertebrae articulates with the sacrum

Question 3

Label the bones of the posterior abdominal wall

Answer 3

On image

Question 4

What do muscles on the posterior abdominal wall do?

Answer 4

• These muscles act on the vertebral column and cause the muscles to move: anteriorly (flexion), laterally flex the trunk, posterior extension

Question 5

What does quadratus lumborum do?

Answer 5

• Extension of the trunk is permitted by the muscle called quadratus lumborum. This muscle attaches to the 12th rib and the transverse processes of the lumbar vertebrae

Question 6

What does Psoas major do?

Answer 6

• Psoas major muscle acts to flex the trunk, and flexes the thigh at the hip joint. Distally this muscle is merging with iliacus muscle (which resides within the iliac fossa). Together these muscle muscles unit to form iliopsoas and insert onto the lesser trochanter of the femur

Question 7

What does psoas minor do?

Answer 7

Assists flexion of trunk

Question 8

Is the diaphragm a muscle?

Answer 8

• The diaphragm is a muscle! A fibromuscular sheet of muscle that separates the thorax from the abdomen below. The diaphragm has a central tendon which is closely associated to the heart which sits on top of it.

Question 9

What does the right and left crus of the diaphragm attach to?

Answer 9

• The diaphragm has a right dome and left dome. The right dome is slightly higher as it sits on top of the liver. Posteriorly the diaphragm is attached to the vertebrae via the cress, the right cress attaches to the L3 and left attach to L1/L2.

Question 10

What is the arch between the cresses called?

Answer 10

• The arch between the 2 cresses is called the medium arcuate ligament. The is also medial arcuate ligament (continuous with fascia psoas major and psoas minor) and lateral arcuate ligament (continuous with fascia of quadratus lumborum). The aorta runs posterior to the medium arcuate ligament, therefore this ligament makes up part of the aortic hiatus

Question 11

What do the fibres of the diaphragm cress form?

Answer 11

• The fibres of the diaphragm cress help form the lower oesophageal sphincter. Another hiatus of the diaphragm is the caval opening, as the IVC runs through it

Question 12

Label the lower abdominal muscles

Answer 12

On image

Question 13

Label the diaphragm openings

Answer 13

On image

Question 14

Label the diaphragm

Answer 14

On image

Question 15

Where is the lumbar plexus and what does it innervate?

Answer 15

• If you look into the retroperitoneum you will find a collection of nerves. These are branches from the lumbar plexus.
• The lumbar plexus mainly gives motor and sensory innervation to the thigh and the pelvic region. It also gives motor innervation to the muscles of the abdominal wall and also sensory innervation to the parietal peritoneum.

Question 16

What is the subcostal nerve?

Answer 16

• Subcostal (T12) – this nerve runs under the 12th rib. It arises from the 12th spinal thoracic nerve. It takes a horizontal course over the muscle belly of quadratus lumborum and pierces the muscle: transverse abdominus. It will then run between the plane between the internal oblique muscle and transverse abdominus. Not part of the lumbar plexus.

Question 17

What is the illiohypogastric nerve?

Answer 17

• Iliohypogastric (L1) and Ilioinguinal (L1) – arise from the lateral border of psoas major. They take an oblique course around the abdominal wall within the neurovascular plane, giving innervation to the muscles and skin. The Ilioinguinal nerve passes distally it will enter the inguinal canal and will pass out of the superficial inguinal ring. It will continue as the anterior labial nerve, that gives innervation to the skin over the root of the penis/anterior scrotum or the mons pubis and labia for females

Question 18

What is the genitofemoral nerve?

Answer 18

• Genitofemoral (L1 – L2) - Runs on the anterior surface of psoas major. It will branch into a femoral branch (which supplies cutaneous innervation to the anterior thigh) and a genital branch (it courses along the ilioinguinal nerve and travels within the inguinal canal. As it passes out through the superficial inguinal ring it will give cutaneous innervation to the anterior scrotum or labia majora and motor innervation to the cremaster muscle (covering of the scrotum)

Question 19

What is the lateral femoral nerve?

Answer 19

• Lateral femoral cutaneous nerve of thigh (L2 –L3) – supplies cutaneous innvervation to the lateral thigh

Question 20

What is the femoral and obturator nerve?

Answer 20

• Femoral (L2 – L4) – motor and sensory innervation to the thigh, it arises on the lateral border of psoas major
• Obturator (L2 – L4) – arises from the medial aspect of psoas major and supplies the thigh

Question 21

Label the somatic nerves on the posterior abdominal wall

Answer 21

On image

Question 22

What is the root, sensory and motor function of the illiohypogasrtic, illioinguinal nerve and genitofemoral nerve?

Do the same for motor function

Answer 22

On table

Question 23

What ligament does the aorta pass through?

What level does it bifurcate into the common iliac arteries?

Answer 23

• This travels through the aortic hiatus through the median arcuate ligament and descends 13cm before it bifurcates into the common iliac arteries at L4.

Question 24

What do unpaired branches of the aorta supply?

What does the celiac trunk supply and arise from? What branches does it give off?

What are the paired branches of the aorta?

Answer 24

• Along the course of the aorta it gives of paired branches, from the left and right hand side.
• Unpaired branches of the aorta supply the structures of the abdominal cavity.
• Celiac trunk (unpair T12 branch) – this supplies the organs of the foregut. It will then give off 3 main branches: left gastric artery (passes along the lesser curvature of the stomach), splenic artery and common hepatic artery
• Superior mesenteric artery (L1) – supplies the organs of the midgut.
• Inferior mesenteric artery (L3) – supplies the organs of the hindgut
• The paired arteries of the aorta include: inferior phrenic arteries (supply the under surface of the diaphragm), the middle suprarenal arteries (supply renal glands on top of kidneys), renal arteries, gonadal arteries (travel to the pelvis – testes and ovaries) and the lumbar arteries

Question 25

What is an aortic aneurysm?

Answer 25

• This is when there is weakening in the aorta
• The aorta is under high pressure, as it is receiving blood directly from the heart
• Dilation of blood vessel
• Weakening of aortic wall
• If ruptured 90% mortality rate
• Endovascular stent grafting, or endovascular aneurysm repair (EVAR), is a newer / less invasive treatment

Question 26

What forms the inferior vena cava?

Where does it pierce the diaphragm?

What does the left and right gonadal veins drain into?

What veins drain into the IVC from the liver?

Answer 26

• Formed by the joining of the common iliac veins at the level of L5, it travels superiorly and pierces the diaphragm at the level of T8 and will drain into the right atrium
• Formed at L5 by union of common iliac veins.
• Pierces diaphragm at the caval opening at the level of T8
• Drains blood from lower limbs and abdomen and pelvis
• Right godadal veins drains into IVC and right drains into and left gonadal vein drains into the left renal vein
• IVC branches in the liver to form the left, right and middle hepatic veins which drain into the IVC

Question 27

Label the abdominal CT scans

Answer 27

• Image 1: The branch coming of the aorta is likely to be the superior mesenteric vessel because it runs behind the neck of the pancreas
• Image 2: we can see the left renal vein coming off the inferior vena cava and draining the substance of the kidney. If there is an aneurysm of the aorta is can cause a blockage of this path

Question 28

What type of glands are the Suprarenal Glands (adrenal glands)?

Where do they lie?

What are they surrounded by?

Answer 28

• Endocrine glands
• Lie on upper pole of kidney
• Surrounded by renal fascia

Question 29

What is the yellow cortex and brown medulla derived from?

What do they each secrete?

Answer 29

Yellow cortex
• Derived from mesoderm
• Secretes corticosteroids and androgens

Brown medulla
• Derived from neural crest
• Main source of catecholamines (adrenaline and noradrenalin)

Question 30

What is the arterial supply to the Suprarenal Glands?

Label them

Label the venous drainage

Answer 30

• There are 3 main arteries of the suprarenal glands:
• Superior suprarenal glands – arise from the inferior phrenic arteries (a paired branch from the abdominal aorta)
• Middle suprarenal artery – a paired branch from the abdominal aorta
• Inferior suprarenal artery – arising from the renal arteries

Question 31

What are the functions of the kidneys?

Answer 31

• Excretes most of waste products of metabolism
• Controls water and electrolyte balance of body
• Maintains acid-base balance of body
• Secretes hormones and renin into the blood stream
• Kidneys filter approx. 113 to 144 pints of blood every hour
• Filters all blood 400 times a day!
• Blood flow higher than in heart!

Question 32

Describe the development of the kidneys

Answer 32

• The kidneys develop in the pelvis and as the foetus elongates, the kidneys ascends to reside underneath the floating ribs.
• During their initial development they are supplied by the median sacral artery that arises from the bottom of the aorta and then develop a new blood supply from the renal arteries
• Pelvic or ectopic kidneys have not migrated properly

Question 33

Describe the peritoneum of the kidneys

Answer 33

• The kidneys are primary retroperitoneal organs

Question 34

What levels are the kidneys found?

Answer 34

• The left kidney is slightly higher than the right kidney due to the presence of the liver on the on the right hand side
o Superior pole of left kidney: 11th and 12th rib (T12-L3)
o Superior pole of right kidney 12th rib (T12-L3)

Question 35

Label the posterior kidney relations

Answer 35

On image

Question 36

Label the cross section of the kidney

Answer 36

On image

Question 37

Label the internal anatomy of the kidney

Answer 37

Internally, the kidneys have an intricate and unique structure. The renal parenchyma can be divided into two main areas – the outer cortex and inner medulla. The cortex extends into the medulla, dividing it into triangular shapes – these are known as renal pyramids (loops of nephrons and collecting ducts which collect urine from filtered blood).
The apex of a renal pyramid is called a renal papilla. Each renal papilla is associated with a structure known as the minor calyx, which collects urine from the pyramids. Several minor calices merge to form a major calyx. Urine passes through the major calices into the renal pelvis, a flattened and funnel-shaped structure. From the renal pelvis, urine drains into the ureter, which transports it to the bladder for storage.
The medial margin of each kidney is marked by a deep fissure, known as the renal hilum. This acts as a gateway to the kidney – normally the renal vessels and ureter enter/exit the kidney via this structure. Vein is the most anterior structure, then renal artery then ureter.
Sympathetic fibres and lymphatics also pass through the hilum
Perinephric fat extends into kidney to form the renal sinus

Question 38

Name the structures of the renal hilum from anterior to posterior, what else runs through the hilum?

Answer 38

• Renal Hilum
• Transmits, from anterior to posterior, the renal vein, renal artery & the ureter (VAU).
• Lymph vessels & sympathetic fibers also pass through the hilum.

Question 39

What is the renal sinus?

Answer 39

• Contains the renal pelvis: upper expanded part of the ureter.
• Perinephric fat is continues into the hilum and the sinus and surrounds all these structures.

Question 40

Label the arterial supply of the kidneys

Answer 40

On image

Question 41

Label the venous supply of the kidneys

Answer 41

On image

Question 42

What do the ureters do?

How long are they?

What are the walls made of?

Answer 42

• Urine that is produced in the kidney then has to be in the bladder, it will pass through the ureter
• 25-30cm long
• Walls are made of smooth muscle that creates a peristalic wave to propel the urine down into the bladder. They are 3mm in diameter

Question 43

Describe the course of the ureters

Answer 43

Copy

Question 44

What are renal stones are where do they lodge?

Answer 44

• Kidney stones that stretch the walls of the ureter
• Common clinical problem
• May cause distension of muscular tube
• Complete or intermittent obstruction of urinary flow
• Pain referred from ‘loin to groin’
• Ureteric colic is severe intermittent pain due to contraction of ureteric muscles to overcome an obstruction, usually due to stone or clot formation

Question 45

What are the 3 points of ureteric constrictions?

Answer 45

The ureter has constrictions at three points which are potential sites of obstruction and stone impaction:

1. Ureteropelvic junction
2. Crossing of common iliac artery
3. Site of entrance to bladder