Anatomy of the GI System

Question 1

Which vertebral levels does the oesophagus level lie at?

Answer 1

Cricoid cartilage (C6) to cardiac sphincter/orifice (T11)

Question 2

Which vertebral level does the oesophagus begin at?

Answer 2

C6

Question 3

Which vertebral level does the oesophagus end at?

Answer 3

C11

Question 4

At which vertebral level does the oesophagus pierce the diaphragm?

Answer 4

C10

Question 5

Outline the layers of the Oesophagus

Answer 5

MSMA

Mucosa = NK SSE

Submucosa

Muscularis propria: Ext. Longitudinal (1/3 skeletal –> 1/3 smooth muscle) + Inner circular

Adventitia = outer CT layer (as not intraperitoneal)

Question 6

What type of epithelium is present in the Oesophagus?

Answer 6

Non-keratinised stratified squamous epithelium

Question 7

What are the 3 layers of the external longitudinal muscle present in the oesophagus?

Answer 7

• Superior 1/3 = voluntary, striated (skeletal)
• Middle 1/3 = voluntary striated + smooth muscle
• Inferior 1/3 = smooth muscle

Question 8

How many regions of the oesophagus are there? What are they? State the vertebral levels of each.

Answer 8

3 regions

• Cervical (C6-T1)
• Thoracic (T1-T9)
• Abdominal (T10)

Question 9

State the two sphincter of the oesophagus.

Answer 9

UOS (C6) = anatomical sphincter at pharyngooesophageal junction

LOS (T11) = physiological sphincter at gastro-oesophageal junction

Question 10

What is the vertebral level of the UOS?

Answer 10

UOS (C6)

Question 11

What is the vertebral level of the LOS?

Answer 11

LOS (T11)

Question 12

State the oesophageal constrictions.

Answer 12

ABCD

• Arch of aorta
• Bronchus (L)
• Cricoid cartilage
• Diaphragmatic hiatus (T10)

Question 13

Outline the blood supply to the oesophagus.

Answer 13

• Oesophageal branch of Inferior Thyroid Artery (Fr. Thyrocervical Trunk)
• Oesohageal arteries (Fr. Thoracic aorta)
• Left Gastric artery

Question 14

Outline the venous drainage of the oesophagus.

Answer 14

Oesophageal veins (into inferior thyroid vein, azygous, hemi-azygous and accessory azygous)

Left gastric vein (into portal vein)

Question 15

Outline the innervation of the oesophagus

Answer 15

Oesophageal plexus (SNS + PSNS)

Cervical region:
Cervical sympathetic trunk
Recurrent laryngeal nerve (CN X)

Thoracic region:
Sympathetic trunk
Vagus nerve (L + R trunks)

Abdominal region: 
T5-T12 spinal nerves
Vagus Nerve (L + R trunks)

Question 16

Outline the lymphatic drainage of the oesophagus.

Answer 16

Deep cervical nodes

Para-tracheal nodes

Posterior mediastinal nodes

Thoracic duct

Coeliac lymph nodes

Question 17

What is the stomach?

Answer 17

intraperitoneal, abdominal J-shaped digestive organ which is present at vertebral levels T11-L1, beginning at the cardiac orifice (T11) and ending at the pyloric canal (L1)

Question 18

Outline the main functions of the stomach.

Answer 18

Digestion

HCl secretion

Hormone secretion

IF production

Question 19

Outline the 4 regions of the stomach

Answer 19

Fundus

Cardia

Body

Pylorus

Question 20

At what vertebral level does the stomach begin and end?

Answer 20

T11-L1

Question 21

Which sphincters control influx and efflux of gastric contents.

Answer 21

Cardiac sphincter (LOS) at T11

Pyloric sphincter at L1

Question 22

What point does contiguous epithelia of the oesophagus and stomach transition?

Answer 22

SSE to SCE at T11

Question 23

State the anatomical feature of the stomach permitting distension.

Answer 23

Rugae (mucosal folds)

Question 24

Draw the stomach. Include the main anatomical features.

Answer 24

Drawing must show:

• Cardiac sphincter
• Fundus
• Cardia
• Body
• Pylorus
• Pyloric sphincter
• Greater curvature
• Lesser curvature
• Cardiac notch

Question 25

Outline the arterial blood supply to the stomach. Give the origins of each vessel.

Answer 25

Right Gastric Artery (CHA)
Left Gastric Artery (CT)

Right Gastro-omental artery (GDA)
Left Gastro-omental artery (SA)

Question 26

Draw out the arterial supply of the stomach.

Answer 26

Right Gastric Artery (CHA)
Left Gastric Artery (CT)

Right Gastro-omental artery (GDA)
Left Gastro-omental artery (SA)

Question 27

Outline the venous drainage of the stomach.

Answer 27

Drain to HPV:
Right Gastric Vein
Left Gastric Vein

Drain to SMV:
Short Gastric Vein
Right GO Vein
Left GO Vein

Question 28

Outline the innervation of the stomach.

Answer 28

• Anterior + Posterior Vagal Trunks (CN X) (PSNS)

* Greater Splanchnic Nerve (T6-T9)

Question 29

Outline the lymphatic drainage of the stomach.

Answer 29

Gastri LN
Gasto-omental LN

Both drain to:
Coeliac LN

Question 30

What are the vertebral levels of the SI?

Answer 30

L1-L4

Question 31

What are the 4 parts of the duodenum?

Answer 31

Superior (L1)

Descending (L1-3)

Inferior (L3)

Ascending (L3-L2)

Question 32

What junction marks the end of the small intestine?

Answer 32

Ileocaecal junction (L4)

Question 33

What part of the duodenum curves around the head of the pancreas?

Answer 33

Descending Duodenum (L1-L3)

Question 34

A cancer of the Pancreatic head is most likely to compress which region of the Duodenum?

Answer 34

Descending Duodenum (L1-L3)

Question 35

Which region of the duodenum crosses the IVC and Aorta?

Answer 35

Inferior (L3)

Question 36

The ascending duodenum is suspended by which ligament?

Answer 36

Ligament of Treitz

Question 37

Appendicitis detected by which internally and externally rotating the hips when the knee is flexed at 90º is known as what sign?

Answer 37

Obturator Sign

Question 38

Appendicitis detected by right hip extension and relieved by right hip flexion when lying on the side is known as what?

Answer 38

Psoas sign

Question 39

State 3 main differences between the Jejunum and Ileum.

Answer 39

Jejunum:

• Dark red
• Thick wall
• Greater vascularity
• Long vasa recta
• Fewer Arcades
• Numerous plicae circulares

Ileum:

• Paler pink
• Thin wall
• Less vascularity
• Short vasa recta
• Mire Arcades
• Fewer plicae circulares