Anatomy Overview I

Question 1

Define ‘peritoneum’.

Answer 1

A thin (singles cell thick) serous (lubricated) layer, which lines the abdominopelvic cavity and surrounds the organs within it.

Question 2

Define ‘intraperitoneal’ and list all the organs that are classed as such.

Answer 2

Within the peritoneum

• Stomach
• Spleen
• Liver
• Duodenum (first section)
• Jejunum
• Ileum
• Colon (transverse and sigmoid)

Question 3

Define ‘retroperitoneal and list all the organs that are classed as such’.

Answer 3

Organs have peritoneum on their anterior side only

SAD PUCKER; 
S = Suprarenal (adrenal) Glands
A = Aorta/IVC
D = Duodenum (except the first section)
P = Pancreas (except the tail)
U = Ureters
C = Colon (ascending and descending)
K = Kidneys
E = (O)esophagus
R = Rectum

Question 4

Define ‘omenta’.

Answer 4

• Double folds of peritoneum passing from stomach and duodenum to other organs/body wall
• Structurally similar to mesentery
• Often form sheets over organs
• Composed of mostly fat

Question 5

Describe ‘mesentery’.

Answer 5

Peritoneal extensions that serve as a conduit for blood vessels, nerves and lymphatic vessels to intraperitoneal organs.

Question 6

Describe the falciform ligament.

Answer 6

Attaches the liver to the anterior abdominal wall and separates the liver into the right and left lobes.

Question 7

Describe the mesentery of the small intestine.

Answer 7

It is the biggest fold of peritoneum, so it often called the greatest mesentery.

Question 8

Describe the omental bursa.

Answer 8

The peritoneal cavity is divided into a greater and lesser sac that are connect by a short ‘neck’ called the epiloic foramen.

Question 9

Describe the structure of the GI tract.

Answer 9

(Small intestine) duodenum –> jejunum –> ileum –> (large intestine) caecum –> ascending, transverse, descending colon –> sigmoid colon –> anal canal –> rectum

Question 10

Describe the lymphatic drainage of the different parts of the gut tube.

Answer 10

• Thoracic duct receives most of lymph from abdominal wall and abdominal organs
• Lymphatic vessels run with their corresponding arteries
• Lymphatic nodes form groups around major arteries and abdominal aorta

Question 11

Name the vein that drains the GIT, as well as its formation and location.

Answer 11

Portal vein: collects poorly oxygenated but nutrient-rich from GIT (spleen, pancreas, gallbladder) and carries it to liver.

Formation: by union of splenic and superior mesenteric vein.

Location: behind neck of pancreas (L2).

Question 12

Explain how abdominal pain can be referred and give examples.

Answer 12

Foregut (R + L hypochondrium and epigastrium): peptic ulcer, gastric disease, biliary/pancreatic disease, hepatic disease.

Midgut (R + L lumbar and periumbilical): appendicitis, small bowel obstruction, proximal colon cancer.

Hindgut (R + L iliac fossa and hypogastrium): large bowel obstruction, diverticular disease, carcinoma of colon.

Question 13

Describe the three constrictions of the oesophagus.

Answer 13

Cervical (pharyngo-oesophageal): 15cm from incisor teeth

Thoracic (broncho-aortic): crossed by arch of aorta and left main bronchus

Diaphragmatic: passes through oesophageal hiatus (T10) of diaphragm.

Question 14

Describe the production, transportation and storage of bile.

Answer 14

Production: in the liver.

Stored and concentrated: in the gallbladder (up to 50ml).

Transportation: biliary ducts carry bile from liver to gallbladder.

Question 15

Name the artery that supplies the gallbladder and describe its location.

Answer 15

Cystic artery lies in the Triangle of Calot (between common hepatic duct, cystic duct and visceral surface of liver).

Question 16

The pancreas: state its function, peritonisation, location (by surface marking), and associated structures.

Answer 16

• Accessory digestive gland is both exocrine (pancreatic juice) and endocrine (insulin and glucagon)
• Retroperitoneal
• Lies along the transpyloric line (L1-2)
• Portal vein is formed behind the neck of the pancreas

Question 17

The spleen: state its function, peritonisation and location (by surface marking).

Answer 17

• Mobile haemo-lymphoid organ
• Entirely covered by peritoneum except at hilum (‘bare’ area)
• Located in left hypochondrium with ribs 9-11 on left side

Question 18

Name two causes of splenomegaly.

Answer 18

• Anaemia

- Typhoid fever

Question 19

Name the main artery that supplies the foregut, its origin and its three main branches.

Answer 19

Coeliac trunk.

Origin: abdominal aorta (T12).

1. Left gastric artery: runs along lesser curvature of stomach.
2. Hepatic artery: supplies liver and gallbladder.
3. Splenic artery: runs retroperitoneally along superior margin of pancreas.

Question 20

State the structures found in the midgut.

Answer 20

• Small intestine including duodenum
• Caecum
• Appendix
• Ascending colon
• Proximal 2/3rds of transverse colon

Question 21

Describe the anatomy of the duodenum and the substances it receives.

Answer 21

• Shortest, widest and most fixed part of the small intestine
• 2nd section receives bile and pancreatic duct

Question 22

Describe the characteristics of the jejunum.

Answer 22

• Deeper red
• Thick and heavy wall
• Greater vascularity
• Long vasa recta
• Few large loops creating arcade
• Few Peyer’s patches
• Less fat in mesentery

Question 23

Describe the characteristics of the ileum.

Answer 23

• Pale pink
• Thin and light wall
• Less vasculairty
• Short vasa recta
• Many short loops creating arcade
• Many Peyer’s patches
• More fat in mesentery

Question 24

Name the main artery that supplies the midgut, its origin, relations and main (and other) branches.

Answer 24

Superior mesenteric artery.

Origin: branch of abdominal aorta (L1).

Relations: crossed anteriorly by splenic vein and neck of pancreas.

Main branches: jejunal and ill arteries.

Other branches: middle colic, right colic, iliocolic.

Question 25

Describe the structures found in the hindgut.

Answer 25

- Distal 1/3rd of transverse colon - Descending colon - Sigmoid colon - Rectum - Upper part of anal canal - Epithelium of urinary bladder and most of urethra

Question 26

Name the main artery that supplies the hindgut, its origin, and branches.

Answer 26

Inferior mesenteric artery. Origin: anterior branch of abdominal aorta (L3). Branches: left colic, sigmoid arteries and superior rectal artery (terminal branch).

Question 27

Describe the features that make the large intestine distinguishable from the small intestine.

Answer 27

- Omental appendices: small, fatty, peritoneal-like projections - Haustra/sacculations - Teniae coli: thickened bands of smooth muscle (longitudinal layer)

Question 28

Describe the anatomy of the appendix, its position and clinical relevance.

Answer 28

- Blind intestinal diverticulum with masses of lymphatic tissue - Variable in position (most common is retrocaecal) - Macburney's point: site of maximum tenderness in acute appendicitis

Question 29

At what vertebral level is the recto-sigmoid junction?

Answer 29

S3.

Question 30

What type of epithelium covers the anal canal?

Answer 30

Columnar above dentate/pectinate line, squamous below.

Question 31

What structures can be palpated through the rectum (in males, females and both)?

Answer 31

Males: prostate and seminal gland. Females: cervix. In both; - Ischial spines and tuberosities - Enlarged internal iliac lymph nodes - Swelling in the ischioanal fossa - Sacrum and coccyx - Collections in rectovesical (male) and rectouterine (female) fossa

Question 32

Describe the autonomic innervations of the abdominal organs.

Answer 32

Parasympathetic (innervates peristalsis); - Vagus nerve (10th cranial nerve) - Pelvic splanchnic nerves (S2-4) Sympathetic (T5-L2/3); - Abdominopelvic splanchnic nerves (greater - T5-9, lesser - T10-11, least - T12) - Prevertebral sympathetic ganglia - Abdominal aortic plexus

Question 33

Describe the sites and associated condition of porto-systemic anastomoses.

Answer 33

- Portocaval shunts - Venous enlargements (varices) during portal obstruction Anorectal junction: haemorrhoids or piles. Gastroesophageal junction: oesophageal varices. Paraumbilical: caput medusae.

Question 34

Describe the placement of the three terminal groups of lumbar lymph nodes.

Answer 34

1. Pre-aortic (ceoliac, superior and inferior): drains organs supplied by anterior branches of aorta. 2. Lateral aortic: drains organs supplied by lateral aortic branches. 3. Retro-aortic: drains posterior abdominal wall.