Stomach Flashcards
1
Q
What factors influence the form and position of the stomach?
A
- Posture and build of the individual
- Extent to which the stomach is filled
- Position of the surrounding viscera
- Tone of the abdominal wall and
- Gastric musculature
2
Q
Where is the stomach found?
A
Found within the superior aspect of the abdomen and spans the epigastric, left hypochondriac and umbilical regions
3
Q
Describe the shape of an empty stomach
A
commonly J-shaped
4
Q
What are the different types of stomach?
A
- Sthenic [normal]
- Hypersthenic
- Hyposthenic
- Asthenic
5
Q
What is the clinical significance of hypersthenic stomachs?
A
Very oblique → prone to duodenal ulcers
[seen in obese patients]
6
Q
What is the clinical significance of hyposthenic stomachs?
A
vertical → prone to gastric ulcers
7
Q
What are the 4 subdivisions of the stomach?
A
- Cardia
- Fundus
- Body
- Pylorus
8
Q
What is th emost fixed part of the stomach?
A
Cardia
9
Q
what is the cardia of the stomach?
A
found at T11, it surrounds the esphageal orifice
10
Q
What is the funduc of the stomach?
A
dome shaped portion of the stomach that lies above a horizontal line from the cardiac notch to the greater curvature of the stomach
11
Q
Relations of the Fundus
A
Lies in contact with left dome of diaphragm
apex level with left 6th rib anteriorly
12
Q
What is the body of the stomach?
A
the largest of the stomach, that extends from fundus to angular incisiure superiorly and the from the fundus to an inconstant indentation inferiorly
13
Q
What is the contents of the fundus?
A
Gas
14
Q
What is the Pylorus of the Stomach?
A
portion of the stomach that connects it to the duodenum
15
Q
What are the parts of the Pylorus?
A
- Pyloric antrum
- Pyloric canal
- Pyloric sphincter
16
Q
Where is the Cardiac Orifice found?
A
- on body at left 6/7th costal cartilage in erect position
- lies ~2.5 cm away from the median plane at T11
17
Q
What marks the pyloric orifice?
A
dentified by thick pyloric sphincter (in cadaveric specimen by green-colored bile stain)
18
Q
Where is the Pyloric orifice located?
A
located at Level of transpyloric plane (tip of 9th costal cartilage anteriorly and L1 vertebral body posteriorly )
19
Q
Cardiac vs. Pyloric Orifice
A
Pyloric orifice is more superficial than cardiac orifice & more mobile
20
Q
Which curvature of the stomach is more fixed?
A
Lesser Curvature of the Stomach
21
Q
What does the angular notch indicate?
A
indicate junctions of body and pyloric region
22
Q
Which arteries are found along the lesser curvature of the stomach?
A
Right and Left Gastric arteries
23
Q
Which part of the stomach is more prone to ischemia and why?
A
- lesser curvature
- has minimal arterial anastomosis, which when occluded would leaf to ischemia and ulcerations
24
Q
What structure is attached to the lesser curvature of the stomach?
A
Lesser omentum [hepatogastric ligament]
25
Which arteries run along the greater curvature of the stomach?
short gastric artery
Right and Left gastroepiploic// omental artery
26
What structures are attached to the Greater curvature of the stomach?
1. Gastrophrenic ligament
2. Gastrosplenic ligament
3. Anterior 2 layers of the Greater Omentum
27
Superior relation of the stomach
1. Eosphagus
2. Left dome of the Diaphragm
28
Anterior relations of the Stomach
1. Diaphragm
2. Greater Omentum
3. Anterior Abdominal wall
4. Left lobe of the liver
5. Gall bladder
29
Posterior relations of the Stomach
1. Lesser sac (omental bursa)
2. Pancreas
3. Left kidney and adrenal gland
4. Spleen
5. Splenic artery
6. Transverse colon
7. Transverse mesocolon
8. Left crus of the diaphragm
30
What structure is affected by posterior perforation of the stomach?
Contents of the stomach bed, especially the splenic artery
31
Inferior and Lateral relations of the Stomach
Transverse mesocolon
32
Empty vs. Distended stomach
***Empty***: surfaces tend to face superiorly and inferiorly, rather than anterior and posterior
***Distended:*** surfaces become progressively more anteriorly and posteriorly
33
What are some possible effect of pancreatitis on the stomach?
posterior wall of the stomach may adhere to the posterior wall of the lesser sac that covers the pancreas
34
What is the gastric triangle and what is the clincal significance of this space?
1. Anterior surface of the stomach where it is in direct contact with the anterior abdominal wall
2. A feeding tube is inserted through this area in cases of complete esophageal obstruction
35
What are the boundaries of the Gastric triangles?
* **R:** inferior border of the liver
* **L:** left costal margin
* **Inferiorly:** transverse colon
36
What are the boundaries of Traube's space?
* **S**: lower border of left lung
* **I:** left costal margin
* **Right side**: lower border of left lobe of liver
* **Left side:** spleen
37
What is Traube's space?
Topographic area overlying the fundus of the stomach
38
What is the clinical significance of Traube's space?
***Examination:*** tympanic on percussion
***Pathology:*** the space is obliterated by enlargement of liver, spleen or left-sided pleural effusion
39
Describe the interior surface of the Pyloric Orifice
Mucosa appears slightly thickened, forming part of the ‘mucosal rosette’ that lines the orifice and contributes to its closure
40
Describe the interior surface of the Gastric Canal
Smoother mucosa along lesser curvature forms a temporary, continuous furrow ‘gastric canal’
41
Function of Gastric Canal
Facilitates saliva and liquids entering stomach to be fast-tracked to the pylorus during swallowing,
42
Which portion of the interior surface of the stomach prone to injury and why?
Gastric canal is prone to injury by irritant liquids
43
Interior of the Stomach
Gastric Rugae and Gastric canal
44
Describe the appearance of the gastric rugea is a distended and empty stomach
**Distended:** disppear
**Empty:** contracted or shrunken state
45
Gastric Rugae
Are mucosal longitudinal folds with submucosal CT found in the body and, to a lesser extent, the fundus
These are most obvious on the anterolateral, lateral and posterolateral parts of stomach, towards greater curvature.
46
What are the two sphincters of the stomach? Which is anatomic and physiologic?
**Cardiac Orifice:** physiological
**Pyloric orifice/Sphincter:** anatomical
47
Branching of the Celiac trunk
48
What are the branches of the Splenic artery supply the stomach?
1. Short gastric
2. Left gastro-epiploic
3. Posterior Gastric
49
What are the branches of the Common hepatic artery supply the stomach?
Gastroduodenal artey
1. Right gastric
2. Right gastroepiploic
50
Path of Pyloric artery
They pierce duodenal wall around its entire circumference just distal to the sphincter and reach submucosa of the pyloric canal and terminate in mucosa of pyloric antrum
51
What is the terminal branch of gastroduodenal artery?
Right gastro-omental artery
52
Arterial anastomosis of the cardia/esophagus
Esophageal arteries originating from thoracic aorta anastomose with vessels supplying the fundus of stomach in cardiac orifice region.
53
Arterial anastomosis of the pylorus
extensive network of vessels supplying the duodenum allows for some anastomosis between branches of the superior mesenteric artery and pyloric vessels derived from arteries arising from the coeliac trunk.
54
Arterial anastomosis of the greater curvature
anastomoses by right and left gastro-omental aa
55
Arterial anastomosis of the lesser curvature
Anastomoses form along lesser curvature by right and left gastric arteries
56
Arterial anastomosis of the fundus
Anastomoses exist in the fundus between short gastric and left gastric aa
57
Arterial anastomosis of the antrum
Anastomoses between the right gastric and right gastroepiploic aa
58
In which part of the stomach do we see extensive anastomoses
59
What is a site of portocaval anastomosis in the stomach?
Lower end of esophagus
60
Venous drainage of the stomach
1. hepatic portal vein
2. Splenic vein
3. Superior mesenteric vein
61
What veins drain into the superior mesenteric vein?
Short gastric vein, left and right gastro-omental veins
62
What veins drain into the hepatic portal vein?
Right and left gastric veins
63
Congenital (Infantile) hypertrophic pyloric stenosis
1. Hypertrophied circular muscles of the pylorus sphincter, with narrowed lumen
* treated by pyloromyotomy
2. → distension of stomach → projectile vomiting [two weeks-two months]
* Vomit does not have bile
3. Incidence is common in monozygotic twins
64
Lymphatic drainage of the Stomach
65
What is Trosier’s sign?
enlarged & palpable left supraclavicular node may be the first sign of gastric cancer
66
Is the following statement true or false, and explain why?
"Carcinoma of the stomach readily spreads into duodenum than esophagus"
False, near the pyloric end of the stomach, the gastric lymph vessels fail to communicate with the duodenal lymph plexus due to the pyloric sphincter
67
Lymphatic drainage of the gastro-esophageal junction
continous with those draining lower esophagus
68
Lymphatics of other organs are important for draining the stomach during disease. What are these organs?
Liver and Pancreas
69
Sympathetic supply of the stomach is derived from?
(T5) T6 to T10 (T12)
70
Pain sensation from stomach
1. Poorly localized pain
2. pain referred to epigastric region
* gastro-esophageal junction to lower retrosternal and subxiphoid areas
71
Sympathetic nerve of Stomach
* Postganglionic fibers reach peri-arterial coeliac plexus through greater and lesser splanchnic nn.
* Additional innervation comes from hepatic plexus, which pass to upper body and fundus via lesser omentum
72
Action of Sympathetic system on stomach
* Inhibitorytogastricmusculature → suppress gastric motility
* Motor to the pyloric sphincter → causes vasoconstriction, and constricts the pylorus
* Main pathway for pain sensation → Afferent sensory pathways, including pain, travel with sympathetic efferentn n.
* Vasomotor to the blood vessels
73
Parasympathetic supply of the stomach is derived from?
Right and left vagus through esophageal plexus, coeliac plexus & gastric nerves
74
Action of Parasympathetic System on Stomach
* Motor to gastric musculature (increases peristalsis/gastric motility)
* Inhibitory to the pyloric sphincter (relaxation)
* Secretomotor to the glands of the stomach (increase gastric juice)
* Vagus nn also carry sensations of pain, fullness, and nausea from stomach
75
Where is the pyloric sphincter located?
1–2 cm to the right of midline in transpyloric plane (lower border of L1). [supine position + empty stomach]
76
What marks the location of the pyloric sphincter?
Prepyloric vein, which crosses the anterior surface in a caudal direction
77
What forms the pyloric sphincter?
* Circumferential thickening of circular smooth mm
* interlaced with CT septa and
* some longitudinal mm fibers
78
What are the four layers of the stomach?
1. Mucosa
* epithelium
* lamina propria
* muscularis mucosa
2. Submucosa
3. Muscularis externa
4. Serosa
79
Where are gastric glands located?
in LP
80
What type of epithelium lines the stomach?
Simple columnar epithelium
81
Surface mucous cells
apical cups of mucinogen granules
82
Function of surface mucous cells
secretes thich, viscous alkaine, gel-like coat that adheres to the epithelial layer to protect it
83
What makes the secretios of surface mucous cells alkaline?
High levels of Bicarbonate and Potassium
84
What role does Prostaglandin have in protecting the gastric mucosa?
1. Stimulate secretion of bicarbonates
2. increase thickness of mucous layer with vasodilation in lamina propria.
3. improves blood supply to any damaged area of gastric mucosa
85
What can the stomach lining absorb?
* Water
* Salts
* Alcohol
* Lipid Soluble drugs
86
How can drugs enter the lamina propria?
Drugs [aspirin, NSAIDs] damage the surface epithelium
87
What are gastric pits?
Invaginations of th surface epithelium that extends to muscularis mucosa. The base of each pit recieves several gastric glands
88
What are the 3 types of Gastric glands and how are they classified as?
Classified according to the region where its found
1. Cardiac glands [cardia]
2. Principal glands [fundus+body]
1. Pyloric mucus-secreting glands [pylorus]
89
Describe the appearance of Principal glands
flask shaped with short gastric pits, that are found in the fundus and body of the stomach
90
What type of cells populate the principal cells?
digestive enzyme producing parietal and chief cells,
91
Describe the appearance of pyloric mucus-secreting glands
small glands with long gastric pits that have convoluted tubes into base of deep gastric pits
92
What type of cells populated the Pyloric mucus-secreting glands?
mucus-secreting cells but they also contain neuroendocrine cells, especially G cells (secrete gastrin) when activated by appropriate mechanical stimulation (causing increased gastric motility and secretion of gastric juices).
93
Mucous neck cells
* Cells that are shorter than surface cells and are typically mucus-secreting cells, displaying apical secretory vesicles, containing mucins, and basally displaced nuclei
* *Release of mucinogen granules is induced by vagal stimulation*
94
Where is the serosa absent?
* At the attachment sites of the greater and lesser where peritoneal layers are separated by vessels and nerves.
* Over a small superioposterior area near the cardiac orifice where the stomach is attached to the diaphragm via gastrophrenic and gastropancreatic folds.
95
Epithelium of Serosa
Mesothelium [simple squaomous that secrete serous fluid]
96
What three layers form the muscularis externa?
1. Inner Oblique
2. Middle Circular
3. Outer Longitudinal
97
Function of inner oblique layer of muscularis externa?
Works in unison with other layers to produce physical motion and contractions of the stomach required for digestion
98
Function of middle circular layer of muscularis externa
plays an important role in forming the pyloric sphincter
99
describe the changes of the muscularis externa in the different parts of the stomach
* **Cardia:** 3 layers are well developed to create a sphincter to prevent acid reflux
* **Fundus:** poorly developed [lot less churning in this region]
* **Pylorus:** muscularis externa is well developed [to propel chyme into duodenum]
* **Body:** all layers present except in the anterior and posterior part of stomach, where the longitudinal muscle is largely absent
100
inner oblique muscle
* arranged in ‘U’ shaped loops
* Fails to reach the lesser curvature stomach due to cardiac notch
* Contraction of right free margin of the oblique muscle decreases angle between stomach and esophagus → prevents reflux of gastric contents into esophagus
101
Where is the myenteric (Auerbach's) plexus located?
Within the muscularis externa
102
myenteric (Auerbach's) plexus
carries both sympathetic and parasympathetic fibers to smooth muscle layers
103
What controle the activity of ICC?
Autonomic Nervous System
104
Function of muscularis mucosa
help expel the secretions of the gastric glands into the stomach lumen.
105
Layers of Muscularis mucosa
smooth muscle [inner circular and outer longitudinal layer]
106
What is found within the Lamina Propria?
blood and lymphatic vessels, complex peri-glandular vascular plexus, and lymphoid tissue (gastric lymphatic follicles)
107
Where is Meissner's plexus found\>
within the submucosa
108
Submucosal (Meissner’s) plexus
Parasympathetic innervation
109
Submucosa
* durable, yet flexible and mobile
* rich in vasculature and lymphatics
110
Replacement period for different cells in the stomach
* Surface and gastric pit cells turnover is 4 to 7 days
* Typical replacement period for surface mucous cells is 3 days
* Mucous neck cells is 1week.
111
Where are stem cells located?
ituated in the isthmus of the gland and bases of gastric pits (transitional area between gastric glands and gastric pits)
112
Where are chief cells located?
in deeper part of fundic glands
113
What do chief cells secrete?
pepsinogen and gastric lipase
114
Appearance of Chied cells
* basophilic cuboidal cells with rounded and euchromatic nuclei
* smaller than parietal cells
* located basally
115
What do Chief cells contain?
Contain secretory zymogen granules and their abundant cytoplasmic RNA renders them strongly basophilic.
116
What do parietal cells secrete?
gastric acid [hydrocholic acid] and Intrinsic factor
117
Changes of Parietal cells
* precise structure of the cell varies with its secretory phase:
* When stimulated, number and surface area of microvilli increase up to five-fold, probably as a result of the rapid fusion of the tubulovesicular system with the plasma membrane.
* At the end of stimulated section this process is reversed, when the excess membrane retreats back into the tubulo-alveolar system and microvilli are lost.
118
Appearance of Parietal cells
* Are large, oval and strongly eosinophilic, and have centrally placed nuclei.
* Occur intermittently along the walls of the more apical half of the gland but can reach as far as the isthmus;
* Bulge laterally into the surrounding connective tissue
119
structure of parietal cells
* Luminal aspects: covered by plasma membraine rich in H+/K+ ATPase antiporter changes
120
What enhances the secretion of hydrocholic acid?
Histamine + Gastrin produced by Enteroendocrine cells
121
Where are enteroendocrine cells located?
Scattered throughout all types of gastric glands but more frequently in the body and fundus of the stomach
122
Function of enteroendocrine cells
control of gut motility and glandular secretion.
123
What are the different enteroendocrine cells of the stomach and what is their functions?
* gastrin producing G cells (stimulate gastric acid secretion) ;
* somatostatin producing D cells;
* histamine producing ECL (enterochromaffin-like) cells;
* Serotonin-producing enterochromaffin cells;
* ghrelin-producing P/D(1)-type endocrine cells (stimulate growth hormone
* secretion and also appetite and perception of hunger)
