Session 7

Question 1

Function of the liver

Answer 1

Catabolism:

RBC breakdown -> biliverdin -> billurubin -> conjugated bilirubin (WATER SOLUBLE glucoronic acid by UDP glucuronyl transferse) -> bile -> SI (stercobillin/ urobilinogen)

Anabolism

• Albumin
• Glycogen
• Numerous coagulation factors
• Haematopoiesis in fetus (can be revived in adult if bone marrow failing)
• cholesterol

Catabolism/breakdown/toxin degredation

• Drugs/poisons (cytochrome P450)
• Hormones
• Haemoglobin
• Can take over removal of aged red cells after splenectomy

4. Storage -> glycogen, triglyceride, protein

Question 2

Liver function tests

Answer 2

Question 3

1. ALP present is present in the ? Thus a raised ALP can be due to ?
2. Using these blood test results state what type of jaundice the patient has
   Blood test results:

Bilirubin 63 (3-17 mol/L) 
Alanine transaminase (ALT) 3100 (3-40 iu/L) 155 
Alkaline phosphotase (ALP) 155 (\<150 iu/L) 
Haemoglobin (Hb) 145 (135-180 g/L)

3. In the diseases in the table state if ALP, ALT or Gamma GT would be inc or dec

Answer 3

1. liver canaliculi, bile ducts & bone

Bone disease, liver disease, particularly with cholestasis or biliary obstruction

Growth

Question 4

Q. Ultrasonography is a key investigation in the investigation of liver disease. Why?

Answer 4

A. – Because it is very sensitive in detecting biliary obstruction

– Because it can detect:

- hepatic fibrosis

– cirrhosis

– fatty infiltration of the liver

– portal hypertension

– ascites

– gallstones in the gallbladder

– Because it can detect liver metastases

Question 5

1. Distinguish pre-hepatic, hepatic and post-hepatic jaundice

Answer 5

1. Pre-hepatic jaundice: Too much bilirubin (e.g. haemolytic anemia)

Intra-hepatic: Failure of hepatocytes to conjugate and/or secrete most of the bilirubin presented to them (e.g hepatitis, cirrhosis). Stasis within the liver is called cholestasis

Post-hepatic jaundice: Failure of the biliary tree to convey the conjugated bilirubin to the doudenum (e.g. biliary tree obstruction)

Question 6

1. Conjugated bilirubin is water soluble and if serum levels are raised it will be excreted in the urine. What is the clinical significance?
2. Can be measured with a dipstick. In which of three types of jaudice will this be seen?

Answer 6

1. Turn the urine dark yellow
2. Post-hepatic jaundice, Excess urobilinogen will not noticeably colour the urine but can be measured with a dipstick.

Question 7

Answer 7

Question 8

1. What are the effects chronic alcohol consumption? (4) Explain how they occur.
2. How do you treat alcohol dependence? Explain how it works.
3. Pathology
4. Causes of hepatitis (4)
5. The underlying pathology is?
6. Hepatitis B – the acute mortality from liver failure is 1%. However?

Answer 8

2. Disulfiram, inhibitor of aldehyde dehydrogenase, acetaldehyde will accumulate causing symptoms of a hangover
3. Inflamed &/or necrotic hepatocytes
4. – Viral (Hepatitis A, B, C etc..) – Acute alcohol intake – Fatty liver disease – Drugs/toxins
5. Inflamed &/or necrotic hepatocytes that cannot function normally
6. 30% of individuals may go on to develop cirrhosis or hepatocellular cancer
   (Risk of dying low but long term condition, where vaccination can prevent cancer)

Question 9

1. Liver failure:
2. Symptoms of hepatitis ( viral, alcoholic, drug and fatty)
3. Typical blood test findings in acute hepatitis

Describe the consequences of cirrhosis of the liver LO

4. Cirrhosis is due to
5. Difference between cirrhosis and fibrosis

Answer 9

1. Increased susceptibility to infections - 80% are bacterial but also fungal. High mortality!
   Increased susceptibility to toxins and drugs
   Increased blood ammonia due to failure to clear ammonia via urea cycle. Ammonia is
   produced by colonic bacteria and deamination of amino acids – AMMONIA CAUSES HEPATIC ENCEPHALOPATHY - toxins accumulate in brain
2. • Feels generally unwell, particularly if viraemic

• Anorexia ( not metabolising absorbs contents)
• Fever (IL6 by macrophages inc CRP and fribrinogen)
• Right upper quadrant pain (impinge on visceral peritoneumj
• Dark urine
• Jaundice

3. • Normal albumin and INR
   • High serum bilirubin
   • Conjugated bilirubin present in the urine
   • Very high serum ALT
   • Normal or only very slightly raised ALP
   • Normal or only very slightly raised Gamma GT
4. liver fibrosis producing a shrunken hard nodular liver
5. Fibrosis is the first stage of liver scarring.
   Scar tissue builds up and takes over most of the liver - cirrhosis.

Question 10

1. Portal hypertension is defined as portal venous pressure > 20mmHg. It can be caused by?
2. Alcohol, viral hep, fatty liver disease -> Fibrosis leads to (-> cirrhosis) how does this lead to portal hypertension?
3. Sites of portosystemic anastomoses
4. Associated pathology hypertension may lead to?
5. What is the problem with having oesophageal varices ?
6. What is this image showing

Answer 10

1. o Obstruction of the portal vein
   Congenital, thrombosis or extrinsic compression
   o Obstruction of flow within the liver
   Cirrhosis, hepatoportal sclerosis, Schistosomiasis, sarcoidosis)
2. Pressure & occlusion of the hepatic sinusoids -> portal hypertension -> portosystemic shunting, including oesophageal varices. Portosystemic shunting also diverts nutrient-carrying blood away from the liver.
3. Image
4. Haemorrhoids,
   Oesophageal varices
   Caput Medusa
5. Can get Bleeding oesophageal varices -> INR is prolonged (same with haemorrhoids)
6. Caput Medusa (blood flowing in different directions in ligamentum teres

Question 11

1. Blood goes from Portal -> Systemic state the veins the blood backs up through to form
   oesophageal varices, rectal varices, caput medusae
2. Symptoms of cirrhosis (8)
3. Typical blood test findings in cirrhosis
4. Fibrosis leads to:

Answer 11

1. Left Gastric -> Azygous/Oesophageal = Oesophageal Varices
   Superior rectal -> Inferior rectal = Rectal Varices
   Paraumbilical -> Small epigastric of abdominal wall = Caput Medusae

Colic/Splenic/Portal -> Retroperitoneal veins of posterior abdominal wall or diaphragm
Portal veins here are on the posterior aspects (bare areas) of secondarily retroperitoneal viscera or the liver.

2. •Fatigue/weakness
   •Bleeding and bruising easily
   •Swollen abdomen (ascites) (Dec albumin, inc venous pressure)
   •Swollen legs (hypoproteinaemia)
   •Weight loss ( to absorb nutrient)
   •Jaundice
   •Haematemesis and or melaena (dark black stools)
   •Confusion, drowsiness and slurred speech (hepatic encephalopathy) (so much ammonia in blood)
3. • normal!!
   • low albumin and or prolonged INR
   • raised bilirubin
   • rise in ALT
   • Alk Phos usually normal or very mildly raised if a degree of cholestasis
   • Gamma GT may be raised if the underlying problem is alcohol & gamma GT has been induced by alcohol
4. • Pressure on bile canaliculi: reduced ability to excrete toxins, bilirubin

• Replacement of hepatocytes by fibrous tissue : reduced albumin & clotting factors
• Ascites - The high pressure in the portal venous system means blood is backed up into the abdomen. The increase in hydrostatic pressure in the abdomen means less fluid is reabsorbed into blood vessels at the end of capillary beds. If the liver is damaged, reduced oncotic pressure inside the vessels, due to lack of plasma proteins, may also contribute.
• Splenomegaly – Due to subsequent increased B.P. in the spleen

Question 12

Hep, fibrosis, cirrhosis -> causes, pathology, symptoms, typical blood test finding,

Answer 12

Question 13

Describe the causes and consequences of gallstones LO

1. What are the causes of gallstones (think of composition)
2. Biliary duct obstruction. The two main causes are:
3. What are the typical laboratory findings in gallstones which obstruct the biliary tract?

Answer 13

1. 4/5 = excess cholesterol
   1/5 = excess levels of bilirubin
2. – Gallstones migrating from the gallbladder into the common bile duct
   – Carcinoma of the head of pancreas
3. • Tests for hepatocyte inflammation/necrosis (serum ALT) normal or very slightly raised
   • Serum bilirubin very high
   • Conjugated bilirubin present in the urine
   • Tests for bile duct cell dysfunction raised (Alk phos & Gamma GT)

Question 14

1. What is the consequence of the gallstone obstructing the common bile duct?
2. Why is bilary colic worse after eating?
3. What is Acute cholecystitis?

Answer 14

1. • ascending cholangitis
     - bilary colic
     - Acute cholecystitis
2. Move into the neck of the gall bladder/ biliary tree, inflammation (Cholecystitis) and infection of the Gall Bladder. Pain from Gallstones can be worse after eating, as the secretion of cholecystokinin (CCK) will cause the gall bladder to contract.
3. • If a gallstone obstructs the cystic duct then there is stasis of the gallbladder contents – infection risk!!

• The infecting organism is usually E. Coli

Patient presents with severe gall bladder pain but in addition:
– Is systemically unwell

• pyrexic

Question 15

1. The liver is a common site for metastases. Why? And from which organs?
2. Laboratory findings in liver metastases

Describe the causes & consequences of acute pancreatitis LO

3. Comment on prevalence, cause, problems, pathology of acute/chronic pancreatitis

Answer 15

1. Dual blood supply, breast, colon, lung
2. • Raised serum bilirubin
   • Conjugated bilirubin present in the urine
   • Raised Alk Phos
   • ALT and Gamma GT may be slightly raised
   • Serum albumin and INR usually normal
3. Erythema ab igne

Question 16

1. Image?
2. Explain how alcohol and gallstones cause acute pancreatitis

Answer 16

1. Pancreatic pseudocyst: collection of fluid around the pancreas, cyst contains pancreatic enzymes, blood, and necrotic tissue, typically located in the lesser sac of the abdomen.

(usually complications of acute/chronic pancreatitis)

2. • Alcohol - alters the balance between proteolytic enzymes & protease inhibitors, thus triggering enzyme activation, autodigestion and cell destruction

• Gallstones - obstruction in the ampulla of vater/pancreatic duct & a toxic effect of bile salts contribute to activation of pancreatic proteases

Question 17

1. Symptoms of acute pancreatitis
2. Diagnosis of acute pancreatitis
3. • Raised serum amylase or serum lipase
   • CT scan may be used in moderate/severe cases to look for pancreatic necrosis/ pseudocyst
4. Treatment of acute pancreatitis

Describe the presentation of carcinoma of the pancreas LO

4. Carcinoma of the pancreas
   • Nearly all are ?
   • ? % are in the head of the pancreas
   Why is there a 1 year survival 20% and 5 year survival 3%?

Answer 17

1. • Epigastric pain that goes through to the back
   • Vomiting

(Severe: Grey-Turner’s sign (hemorrhagic discoloration of the flanks), Cullen’s sign (hemorrhagic discoloration of the umbilicus))

3. • Analgesia, supportive treatment, in particular fluid resuscitation because these patients can sequester many litres of fluid in their retroperitoneum
   - treat underlying cause
   - nutrition
4. ductal adenocarcinomas, 70, Metastasises early, presents late

Question 18

Q. Clinical presentation of pancreas cancer LO

Answer 18

A. • Anorexia, malaise , fatigue
• Significant weight loss
• Epigastric and/or back pain
• Dark urine (conjugated billirubin)
• Pale stools (bile does not go into gut)
• Pruritis (bile salts)
PRESENTS LIKE EXTRA HEPATIC JAUNDICE
(last 3 can be due to common bile duct obstruction and/or liver metastases)
Over age of 40

Question 19

1. The liver is located where?
2. What surfaces does the liver have?
3. Why is the posteroinferior surface irregular & flat?

Identify and describe the position of: the falciform ligament and ligamentum teres, the coronary, right and left triangular ligaments & the bare area of the liver LO

4. What are the Ligaments of the Liver
5. Function of the falciform ligament?
6. What is the function of the Coronary ligaments (anterior and posterior folds) & Triangular ligaments (left and right)
7. Function of the Lesser omentum

Answer 19

1. right hypochondrium, epigastric areas, extending into the left hypochondrium
2. the diaphragmatic (anterosuperior) & the visceral (posteroinferior)
3. Contact: oesophagus, right kidney, right adrenal gland, right colic flexure, duodenum, gallbladder and the stomach.
4. Falciform ligament, Coronary ligaments (anterior and posterior folds), Triangular ligaments (left & right), Lesser omentum, hepatogastric ligament
5. attaches the anterior surface of the liver to the anterior abdominal wall (the free edge of this ligament contains the ligamentum teres, a remnant of the umbilical vein)
6. attach the superior surface of the liver to the diaphragm
7. hepatoduodenal ligament & hepatogastric ligament

Question 20

1. What is the bare area?
2. The visceral surface of the liver is covered with peritoneum, except at the?

Answer 20

1. The Diaphragmatic surface of the liver is covered with visceral peritoneum, except posteriorly in the Bare Area of the liver, where it lies in direct contact with the diaphragm. There is a deep groove in the bare area, where the inferior vena cava travels.
2. • fossa for the gallbladder
     - porta hepatis a transverse fissure where vessels (hepatic portal vein, hepatic artery and lymphatics) that supply and drain the liver enter & leave it.

Question 21

Identify & describe the position of the left, right, caudate and quadrate lobes of the liver LO

1. The liver is split into what lobes?
2. The attachment of the ? divides the Right Lobe from the much smaller Left Lobe.
3. On the visceral surface, the right and left sagittal fissures split the right lobe with the porta hepatis into the
4. Describe in more detail the location of the caudate lobe
5. Describe in more detail the location of the quadrate lobe
6. What are the three types of hepatic recesses?

Answer 21

1. Two anatomical ( R&L) & two accessory lobes (caudate and quadrate)
2. Falciform ligament
3. Quadrate (anterior and inferiorly)

Caudate Lobe (posteriorly and superiorly)

4. Between the IVC & a fossa produced by the ligamentum venosum (a remnant of the fetal ductus venosus)
5. between the gallbladder and a fossa produced by the ligamentum teres (a remnant of the fetal umbilical vein)
6. Subphrenic spaces (left and right), Subhepatic space, Morisons pouch

Question 22

1. Where is the subphrenic recess located?
2. Where is the subhepatic space recess located?
3. Where is Morisons pouch located?
4. Clinical significance

Answer 22

1. between the diaphragm and liver, either side of the falciform ligament
2. between the inferior surface of the liver & the transverse colon
3. Posterosuperior aspect of the right subhepatic space,

Between the visceral surface of the liver & the right kidney

4. Deepest part of the peritoneal cavity when supine (lying flat), and this is where fluid is likely to collect in a bedridden patienty

Question 23

Identify and describe the structures (such as the hepatic portal vein, hepatic artery & bile duct) in the porta hepatis LO

1. Where is the location of the porta hepatis?
2. The liver has a unique dual blood supply:

Answer 23

2. Hepatic artery proper – supplies the liver with arterial blood. It is derived from the coeliac trunk.
   Hepatic portal vein – deoxygenated blood, nutrients (detoxification, metabolism)

Q. Which main veins drain into the hepatic portal vein?

Question 24

1. Which main veins drain into the hepatic portal vein?
2. The Porta hepatis transmits the following (anterior to posterior order)

Answer 24

• common hepatic duct (leaving) - anterior, right
• hepatic artery proper (entering) - left
• hepatic portal vein (entering) - behind, between duct and artery

nerves and lymphatics

Sympathetic nerves - these provide afferent pain impulses from the liver and gall bladder to the brain. Pain may be referred to the lower pole of the right scapula (T7).

Hepatic branch of the vagus nerve (CN X).

Question 25

Q. The hepatic veins are the veins that drain de-oxygenated blood from the liver into the IVC. There are usually **three upper hepatic veins** draining from the left, middle, & right parts of the liver. These are larger than the group of lower hepatic veins that can number from six to twenty. All of the hepatic veins drain into the inferior vena cava. They are one of two sets of veins connected to the liver, the others are the portal veins. The large hepatic veins arise from smaller veins found within the liver, and ultimately from numerous ? None of the hepatic veins have ? Describe the gross anatomy of the gallbladder LO 2. The gallbladder is a pear-shaped sac, with a storage capacity of 30-50ml. It is typically divided into three parts:

Answer 25

1. central veins of the liver lobules, valves 2. **Fundus**: The rounded, end portion of the gallbladder; which projects into the inferior surface of the liver. **Body**: The largest part of the gallbladder. It is occasionally in contact with the transverse colon and proximal duodenum. **Neck**: Here, the gallbladder tapers to become continuous with the **cystic duct**, leading to the biliary tree. The neck contains a **mucosal fold**, known as **_Hartmann͛s Pouch_**. This is a common location for **gallstones** to become lodged, causing **cholestasis**.

Question 26

1. Hepatocytes produce bile continuously, secreting it into? The canaliculi drain into the ? & then into the ?, which in turn merge to form the ? Shortly after leaving the porta hepatis, these hepatic ducts unite to form the ? which is joined on the right side by the ? to form the ?, which conveys the bile to the duodenum, through the ? Shortly before this, the Pancreatic Duct joins the bile duct.

Answer 26

1. canaliculi, small interlobular biliary ducts, large collecting bile ducts, right & left hepatic ducts common hepatic duct, cystic duct, bile duct, Ampulla of Vater,

Question 27

Answer 27

Question 28

The jejunum is the second part of the small intestine, beginning at the ? where the digestive tract resumes an intraperitoneal course. The third part of the small intestine, the ileum, ends at the ? SI & large

Answer 28

duodenojejunal flexure, ileocaecal junction

Question 29

Jejunum & duodenum

Answer 29

Question 30

1. The Jejunum and Ileum are both derived from the ? As such their blood supply is derived from the ? 2. The **SMA** usually arises from the abdominal aorta at the level of the **L1 vertebra,** approximately 1cm inferior to the celiac trunk, & runs between the layers of mesentery, sending 15-18 branches to the jejunum and ileum. These arteries unite to form loops or arches called ? which gives rise to straight arteries called ?

Answer 30

1. Midgut, Superior Mesenteric Artery, via the Jejunal and Ileal arteries Abdominal Aorta -\> SMA -\> Jejunal Abdominal Aorta -\> SMA -\> Ileal 2. arterial arcades, vasa recta

Question 31

Describe the parts, appearance & blood supply of the large intestine LO The large intestine can be distinguished from the small intestine by:

Answer 31

Question 32

1. What is the cecum? 2. Where is it located? 3. Why may the caecum may be palpable through the anterolateral abdominal wall. 4. What is the relationship of the caecum to the inguinal ligament & the peritoneum.

Answer 32

1. It is a blind intestinal pouch, approximately 7.5cm in both length & breadth 2. Iliac Fossa of the Right Lower Quadrant of the abdomen 3. Gas,feaces 4. - lies within 2.5cm of the inguinal ligament - **Almost entirely enveloped by peritoneum & is mobile - no mesentery = relative freedom, it may be displaced from the iliac fossa, but is commonly bound to the lateral abdominal wall by one or more cecal folds of peritoneum**

Question 33

Appendix 1. What is the appendix and what does it contain? 2. The appendix arises from? 3. What is its relationship to the mesentery/ peritoneum

Answer 33

1. The appendix is a blind intestinal **diverticulum** (6-10cm in length) that contains **masses of lymphoid tissue.** 2. The posteromedial aspect of the caecum inferior to the ileocaecal junction. It is usually retrocaecal, but its position is variable. 3. - short, **triangular** mesentery, the **Mesoappendix**, which derived from the posterior side of the mesentery of the terminal ileum. - The mesoappendix attaches to the caecum and the proximal part of the appendix.

Question 34

1. Right Colic Flexure/ hepatic flexure - flexure lies deep to the ? 2. Relationship of the ascending colon to the peritoneum 3. How does the left colic flexure differ from the right? 4. The transverse colon and its mesentery, loops down often inferior to the level of the iliac crests. The mesentery is adherent to or fused with the posterior wall of the omental bursa. The root of the transverse Mesocolon lies along the inferior border of the pancreas and is continuous with the parietal peritoneum posteriorly. o Being freely movable, the transverse colon is variable in position, usually handing to the level of the umbilicus (L3), but in tall, thin people it may extend down into the pelvis.

Answer 34

1. 9th and 10th ribs and is overlapped by the inferior part of the liver 2. - **ascending colon is narrower than the caecum** - secondarily retroperitoneal (peritoneum anteriorly & on its sides) - separated from the anterolateral abdominal wall by the **greater omentum** * *3. Left Colic Flexure (splenic flexure): - more superior - more acute - less mobile than the right.** It lies anterior to the inferior part of the left kidney and attaches to the diaphragm through the Phrenicocolic Ligament.

Question 35

_Descending Colon_ 1. Relationship to the peritoneum 2. Relationship to the left kidney _Sigmoid Colon_ 1. The sigmoid colon, characterised by its S-Shaped loop of variable length, links the Descending colon & the rectum, running from the iliac fossa to the S3 vertebra. 2. What anatomical changes indicated the rectosigmoid junction? 3. Relationship with the mesentery? Clinical significance? 4. The root of the sigmoid Mesocolon has an inverted V-shaped attachment, extending medially & superiorly along the external iliac vessels to the anterior aspect of the sacrum. 5. The left ureter & the division of the left common iliac artery lie Retroperitoneally, posterior to the apex of the root of the sigmoid Mesocolon.

Answer 35

1. **secondarily retroperitoneal** 2. As it descends, the colon passes anterior to the lateral border of the left kidney. 1. 2. Termination of teniae coli 3. Has a long mesentery ͚Sigmoid Mesocolon͛ - considerable mobility - Volvulus of the Sigmoid Colon

Question 36

Vasculature of the Colon 1. State the derivatives of the Ascending Colon, and Right Colic Flexure 2. Describe the blood supply 3. State the venous drainage of the colon

Answer 36

1. Midgut 2. Abdominal Aorta -\> SMA -\> Ileocolic Abdominal Aorta -\> SMA -\> Right Colic Arteries anastomose with each other, & with the right branch of the **Middle Colic artery.** This forms the first of a series of **anastomotic arcades**, that continues round the large intestine to form a continuous arterial channel, the **Marginal Artery.** 3. Ileocolic & Right Colic Veins -\> SMV -\> portal vein.

Question 37

1. State the derivatives of the transverse colon 2. State its blood supply 3. Venous drainage of the transverse colon is through the?

Answer 37

1. Midgut 2/3 & Hindgut 1/3 2. Abdominal Aorta -\> SMA -\> **Middle Colic (main )** Abdominal Aorta -\> SMA -\> Right Colic (by way of the marginal artery) Abdominal Aorta -\> IMA -\> Left Colic (by way of the **marginal artery**) 3. Middle Colic Vein, which drains into the SMV & subsequently the portal vein

Question 38

1. The descending and sigmoid colon are both derived from? 2. State there blood supply 3. State the venous drainage from the descending & sigmoid colon 1. Relationship of the rectum to the peritoneum 2. The rectum is continuous with the sigmoid colon at the level of S3 vertebra. At this point, the rectosigmoid junction, the teniae coli of the sigmoid colon does what?

Answer 38

1. Hindgut 2. Abdominal Aorta -\> IMA -\> Left Colic Abdominal Aorta -\> IMA -\> Sigmoid 3. Left Colic & Sigmoid Veins -\> IMV -\> Splenic & Portal Veins 1. fixed, primarily retroperitoneal and subperitoneal **First Third - Peritoneum covers the anterior & lateral surfaces Middle Third - Peritoneum only covers the anterior surface Final third No covering, as it is subperitoneal** 2. spread to form continuous outer longitudinal layer of smooth muscle.

Question 39

Vasculature of the Rectum 1. The proximal rectum is derived from? 2. State its blood supply 3. Describe its venous drainage. Clinical significance.

Answer 39

1. Hindgut 2. **Aorta -\> IMA -\> Superior Rectal -\> R+L Branch** Aorta -\> Common Iliac -\> R+L Internal Iliac -\> **R+L Middle Rectal (distal rectum)** Aorta -\> Common Iliac -\> R+L Internal Iliac -\> **Inferior Pudendal -\> R + L Inferior Rectal (distal rectum)** 3. Superior, Middle & Inferior Rectal Veins **Superior Rectal Vein -\> IMV -\> Splenic & Portal vein** **The Middle and Inferior Rectal veins -\> systemic system**

Question 40

1. Anal canal begins? Ends? 2. The anal canal, surrounded by internal and external anal sphincters, descends posteroinferiorly between the? 3. The canal is collapsed, except during the passage of faeces. Both sphincters must relax before defecation can occur. Internally, the superior half of the mucous membrane of the anal canal is characterised by a series of longitudinal ridges called **anal columns**. These columns contain the terminal branches of the **superior rectal artery and vein**.

Answer 40

1. where the Rectal Ampulla narrows at the level of the U-shaped sling formed by the puborectalis muscle, and ends at the Anus. 2. anococcygeal ligament and the **perineal body** 3.

Question 41

Describe the derivatives of the anal canal Describe the blood supply of the anal canal Innervation of the Anal Canal

Answer 41

Above the Pectinate line -\> Hindgut IMA -\> Superior Rectal artery Below the Pectinate line -\> Endoderm Two Inferior Rectal Arteries Middle -\> anastomoses Above Pectinate line (stretching) -\> parasympathetic -\> ganglia S2-S4 (referred pain) Below: pudendal -\> pain, touch and temperature, and pain is well localised