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GIS > GIS05 06 Gross Anatomy Of The GI > Flashcards

GIS05 06 Gross Anatomy Of The GI Flashcards

1
Q

Esophagus

A
  • Muscular tube (~25cm long)
  • Conveys food from pharynx to stomach
  • behind trachea, heart; adjacent to aorta (danger of penetration)

3 parts:

  1. Cervical part (skeletal)
  2. Thoracic part (smooth + skeletal)
  3. Abdominal part (smooth)

3 constrictions:

  1. Upper esophageal constriction (level of cricoid cartilage)
  2. Middle esophageal constrictions (level of aortic arch)
  3. Lower esophageal constriction (level of diaphragm)

Clinical significance:

  • passing instruments through esophagus into stomach
  • viewing radiographs in dysphagia patients
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2
Q

Esophageal hiatus

A
  • Opening in ***muscular right crus of diaphragm
  • Left of median plane
  • Level of ***T10

***Hiatus hernia: Protrusion of stomach into mediastinum through esophageal hiatus

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3
Q

Gastro-esophageal reflux disease (GERD)

A
  • Reflux of stomach content in esophagus
  • ***Barrett’s esophagus: esophageal tissue replaced by tissue more similar to intestinal lining (Stratified squamous non-keratinised —> Simple columnar)
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4
Q

Venous drainage of esophagus

A

Venous plexus in esophageal wall
–> **Portal vein (via gastric veins) / **Azygos vein (via esophageal veins)

Portal hypertension: Esophageal varices / bleeding

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5
Q

***Innervation of esophagus

A

***Esophageal plexus (+ Peri-arterial plexus: around left gastric artery + inferior phrenic arteries)

Esophageal plexus formed by:

SNS:

  • ***Thoracic sympathetic trunk (T2-T4)
  • -> Greater splanchnic nerves (distal esophagus)
  • -> innervate Thoracic + Abdominal part

PNS:

  • formed by ***L/R Vagus nerve
  • -> Anterior/Posterior Vagal trunk
  • -> Anterior/Posterior Gastric plexus
    –> innervate ***Cervical + Thoracic + Abdominal part
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6
Q

Esophageal cancer and lymphatic drainage

A

Lymphatic drainage:

  1. Superior:
    * **Bronchomediastinal trunks
    - -> Internal jugular vein (L/R), Subclavian vein (L/R)
    - -> Brachiocephalic vein (L/R)
  2. Inferiorly:
    * **Celiac nodes (same as Gastric lymph drainage)
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7
Q

Stomach

A
  • beneath dome of left diaphragm
  • adjacent to spleen
  • anterior to pancreas
  • intraperitoneal
  • greater curvature: ***Greater omentum (double fold of peritoneum: 2 layers)
  • when contracted: Gastric mucosa –> ***Gastric rugae (longitudinal folds) –> mixing, ↑ SA for digestion

6 parts:

  1. Cardia (入口)
  2. Fundus (頂部)
  3. Body
  4. Pyloric antrum
  5. Pyloric canal
  6. Pylorus (***Circular sphincter muscle)

Functions (food blender, reservoir):

  1. Enzymatic digestion of food
  2. Accumulation of ingested food
  3. Chemically and mechanically prepare food for digestion –> passage into duodenum

Bariatric surgery –> Adjustable gastric band around stomach to control stomach volume

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8
Q

Blood supply of stomach

A

Celiac trunk —>

  1. ***L Gastric artery (lesser curvature)
  2. Common hepatic artery —> **R Gastric artery (lesser curvature) + Gastroduodenal artery —> **R Gastroomental artery (greater curvature)
  3. Splenic artery —> ***L Gastroomental artery (greater curvature)
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9
Q

***Innervation of stomach

A

SNS:

  • **Greater splanchnic nerve (pre-ganglionic fibre)
  • -> Celiac ganglia (post-ganglionic fibre)
  • -> Anterior/Posterior Gastric plexus

PNS:

  • **L/R Vagus nerve
  • -> Anterior/Posterior Vagal trunk
  • -> Anterior/Posterior Gastric plexus

Normal physiological afferent pathway (e.g. fullness): ***Vagus

Pain pathway: carried by visceral afferent fibre that accompany sympathetic nerve

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10
Q

Vagotomy

A

Surgical section of vagus nerve
Reality - Cut off Anterior / Posterior gastric plexus –> no more visceral afferent pain input (leaving the ***Nerve of Latarjet in place to ensure the emptying function of the stomach remains intact)

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11
Q

Small intestine

A
  1. Duodenum: smallest segment
  2. Jejunum
  3. Ileum (longest)
    - -> Ileocecal junction
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12
Q

Duodenum

A
  • smallest segment
  • wrap around pancreatic head
  • location for most chemical digestion

4 parts:

  1. Superior / First (L1 level, ***Intraperitoneal)
  2. Descending / Second (L2, Intra/Extraperitoneal)
  3. Inferior / Third (L3, Extraperitoneal)
  4. Ascending / Fourth (L3, Extraperitoneal)

Structure:

  • 1st section of superior part: smooth: Ampulla
  • Circular folds: valve of Kerckring
  • **Minor duodenal papilla (上d): orifice for **Accessory pancreatic duct
  • **Major duodenal papilla (落d) (divide foregut and midgut): orifice for **Main pancreatic duct
Duodenal ulcers:
Inflammatory erosions of duodenal mucosa
--> ulcer (esp anterior ones) perforates duodenal wall
--> contents enter peritoneal cavity
--> Peritonitis
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13
Q

Ileum and Jejunum

A
  • 6m long together
  • No clear demarcation
  • Suspended on mesentery (***intraperitoneal)
  • Supplied by Jejunal, Ileal arteries (from ***Superior mesenteric artery, ∵ midgut)
  • Arteries form loops / arches: Arcades
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14
Q

Jejunum vs Ileum

A

Jejunum:

  • **short arcades (usually 1 row), **long vasa recta
  • more circular folds

Ileum:

  • **longer arcades (>= 2 rows), **short vasa recta
  • less circular folds
  • presence of aggregates of lymphoid nodules: ***Peyer’s patches
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15
Q

Ischaemia of intestine

A

Occlusion of vasa recta by:

  • Emboli (clots from elsewhere)
  • Thrombus (clots formed locally)
  • Atherosclerotic occlusion / plaque
  • -> ischaemia of part of intestine
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16
Q

Innervation of Jejunum + Ileum

A

SNS:

  • **Lesser splanchnic nerve
  • -> Celiac + Superior mesenteric ganglia/plexus
  • -> midgut

PNS:

  • **Vagus nerve
  • -> prevertebral plexus
  • -> midgut

Also:

  1. Myenteric plexus
  2. Submucosal plexus
17
Q

Lymph flow of Jejunum + Ileum

A

Specialised function:
Specialised lymphatic vessels called lacteals that absorb fat

Lymph flow:
Juxtaintestinal LN, Ileocolic LN
--> Mesenteric LN
--> ***Superior mesenteric LN
--> ***Intestinal lymphatic trunk
--> Cisterna chyli
--> Thoracic duct --> IVC
18
Q

Large intestine

A
  1. Cecum
  2. Appendix
  3. Ascending colon –> (right colic flexure / hepatic flexure) –>
  4. Transverse colon –> (left colic flexure / splenic flexure) –>
  5. Descending colon
  6. Sigmoid colon
  7. Rectum

Features:

  • Respective mesentery of colon (***Mesocolon)
  • Epiploic appendices (unknown use)

Internal features:

  • ***Haustra
  • ***Taenia coli (free, omental, mesocoli): 3 separate longitudinal ribbons of smooth muscle: contract lengthwise to produce the haustra
  • -> used to locate appendix
  • ***Semilunar fold
19
Q

Structure of Ileocecal valve

A
  • Large intestine begins
  • Cecum: pouch that hangs inferior to the valve
  • -> widest part
  • -> **intraperitoneal + **NO mesentery
  • -> mobile within right iliac fossa
  • Ileocecal valve:
  • Ileocecal orifice (superior and inferior lip/labrum)
  • combination valve + ***weak sphincter
  • -> actively open ***periodically
  • -> entry of ileal contents
  • -> passive ***one-way valve preventing reflux
20
Q

Appendix

A

Vermiform appendix

  • -> intraperitoneal
  • -> mesentery: ***Mesoappendix
  • -> ***Appendicular artery
  • -> related to ***immune function
  • An intestinal diverticulum
  • rich in ***lymphoid tissue
  • Most commonly, appendix is retrocecal (but 32% descends into the lesser pelvis)
  • Anatomical position of the appendix determines:
    1. symptoms
    2. site of muscular spasm and tenderness when the appendix is inflamed

(enters the medial aspect of the cecum, usually deep to the junction of the lateral third and medial two thirds of the spino umbilical line)

(The base of the appendix typically lies in the LRQ, deep to a point that is one third of the way along the oblique line joining the right ASIS (anterior superior iliac spine) to the umbilicus (McBurney point on spino-umbilical line))

21
Q

Colon

A

4 parts:

  1. Ascending
    - superior, ***secondarily retroperitoneal continuation of cecum
  2. Transverse
    - longest and most mobile part
    - level to which it descends depends largely on body type (habitus)
  3. Descending
    - ***secondarily retroperitoneal position
  4. Sigmoid
    - highly variable in length and disposition
    - ending at the ***rectosigmoid junction (located anterior to S3)
    - teniae, haustra, omental appendices cease at the junction
22
Q

Innervation of colon (midgut and hindgut)

A

SNS:

  • **Lesser (T10-T11) + ***Lumbar (L1-L2) splanchnic nerve
  • -> Superior mesenteric + Inferior mesenteric ganglia/plexuses + Inferior hypogastric plexus + Peri-arterial plexus
  • -> midgut + hindgut
PNS:
Before left colic flexure (first 2/3):
***Vagal
--> prevertebral plexus
--> midgut

After left colic flexure (remaining 1/3):

  • ***Pelvic splanchnic nerve (S2-S4)
  • -> inferior hypogastric plexus
  • -> hindgut

Afferent signals:
Middle of sigmoid colon divide Orad / Aborad

Orad (towards mouth):

  • Visceral afferents (Pain) travel retrogradely with ***sympathetic fibers to Spinal sensory ganglia
  • Reflex information travel with ***parasympathetic fibers to Vagal sensory ganglia

Aborad (away from mouth):
- both types of visceral afferent fibres travel with ***parasympathetic fibers to Spinal sensory ganglia

23
Q

Colonoscopy / Sigmoidoscopy

A

Check for colorectal cancer

24
Q

Pancreas

A
  • Accessory digestive gland
  • Exocrine secretion: Pancreatic juice
  • Endocrine secretion: Insulin / Glucagon
  • head wrapped by duodenum: hard to remove during surgery
  • ***secondarily retroperitoneal (except tail)
  • posterior to majority of lesser sac

3 parts:

  1. Head (outermost: Uncinate process)
  2. Neck (anterior to superior mesenteric A/V)
  3. Body (beneath splenic artery)
  4. Tail (intraperitoneal)
  • Pancreatic duct join **Common bile duct —> open at **Major duodenal papilla
  • **Accessory pancreatic duct —> open at ***Minor duodenal papilla
25
Q

Blood supply of pancreas

A
  • **Celiac trunk + Superior mesenteric artery

- -> Pancreatic arteries

26
Q

Liver

A
  • Largest visceral organ
  • All nutrients (except fat) absorbed from GI tract –> go to liver first
  • Right / Left lobe (further divided into segments) –> ***R/L hepatic arteries, hepatic veins and ducts do not communicate –> possible to remove part of liver (e.g. tumour) without excessive bleeding
  • **Intraperitoneal organ + **Ventral mesentery (attach to anterior abdominal wall: ***Falciform ligament (peritoneal folding))
  • Secretes bile
27
Q

Palpation of liver

A
  • Right upper quadrant
  • almost hidden behind thoracic cavity, beneath diaphragm, in front of stomach
  • deep to ribs 7-11 on right side
  • cross midline toward left nipple
  • occupies most of right hypochondrium + upper epigastrium, extend to left hypochrondrium

Movement (facilitate palpation):

  • moves with diaphragm movement
  • located more inferiorly when stand up: gravity
28
Q

Surface of liver

A
  • **1. Coronary ligament –> surround Bare area (attach to diaphragm)
    2. Right / Left triangular ligament (subpart of coronary ligament)
    3. Hepatorenal portion of coronary ligament
    3. Fibrous appendix of liver
  • **4. Falciform ligament
  • **5. Ligamentum teres (Round ligament): remnant of ***closed umbilical vein
    6. Posterior: fissure for Ligamentum venosum
29
Q

Bile system

A
  • Yellow-brown / green fluid
  • -> emulsification of fat
  • produced continuously in liver
  • between meals stored in gallbladder
  • gallbladder concentrate bile by absorbing water and salts
***Bile flow:
Liver (production)
--> Left / Right hepatic duct (from L/R lobe)
--> ***Common hepatic duct
--> ***Cystic duct
--> Gallbladder
--> Cystic duct (secretion)
--> ***Common bile duct (joined by pancreatic duct)
--> Major duodenal papilla
30
Q

Gallstone (Cholelithiasis)

A
  • stone-like deposits within gallbladder
  • abnormal metabolism of bile in gallbladder

2 common types:

  • Cholesterol stones
  • Pigment stones
31
Q

Removal of gallbladder

A

Cholecystectomy

32
Q

Innervation of liver and gallbladder

A

SNS:

  • **Greater splanchnic nerves
  • -> Celiac + Superior mesenteric ganglia/plexus
  • -> liver, gallbladder (***Foregut associated organs)

PNS:

  • **Vagus nerve
  • -> prevertebral plexuses
  • -> liver, gallbladder (***Foregut associated organs)
33
Q

Spleen

A

left, adjacent to tail of pancreas, deep in thoracic cavity (completely hidden)

34
Q

Medial vs Median umbilical ligament

A

Medial umbilical ligament: Remnant of umbilical artery

Median umbilical ligament: Allantois —> Urachus —> MUL

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