Lecture 6 Flashcards
What is the outline of the abdominal cavity?
Abdominal contents not constrained to abdominal cavity
Oesophagus goes through thorax
1/2 way into rib cage
extends down into pelvic cavity- stopping at inguinal ligament and pelvic inlet
Abdominal Aorta
T12-L4 T12= Coeliac trunk (short and stubby) -under diaphragm -Foregut a) Left gastric b) splenic c) Common hepatic L1= Superior Mesenteric (SMA) -MidGut L3= Inferior Mesenteric (IMA -Hind Gut L4= Right and Left common Iliac Arteries
Foregut Component Viscera
Distal Oesophagus
Stomach
Liver and Gall Bladder
Proximal 1/2 of Duodenum
Pancreas- blood supply from 2x sources (Superior Mesenteric Artery)
-Oral Cavity is the start of the Digestive system
-Spleen not foregut
-Referred pain of the stomach is to the Epigastric region
What is the blood supply of the Pancreas?
Blood Supply from 2x sources
- Coeliac axis
- Superior Mesenteric Artery
Foreguts Neurovascular and Lymphatic Supplies
Arterial: branches of Coeliac axis from T12 Abdominal Aorta
Venous: Portal Vein (direct drainage)
Nerve: Coeliac Plexus (T12)
Lymphatics: Pre-aortic nodes T12 (Coeliac nodes)
Stomach Surface Anatomy
Shape and Position changes as stomach fills
Generally Epigastric Region (Left of midline)
Liver= ~Rib 5
Fundus= ~Rib 5-6
Oesophagus= ~Costal Cartilage 7-8
Distal end/Pylorus= Trans-pyloric Plane= ~L1 Vertebral level
3x muscular layers:LOMCOI
1. Longitudinal outer
2. Circular middle
3. Oblique inner - contains Rugae to increase SA surface area and expandability
-Cardia region- before fundus
- 2x Curvatures:
Lesser C: Lesser Omentum attaches
Greater C: Left, inferior,
Stomach Arterial supply
supply from Coeliac Trunk Lesser Curvature: 1. Left Gastric (Direct branch off Coeliac Trunk)-lesser curvature + distal oesophagus 2. Right Gastric (Common Hepatic) -Anastomose Greater Curvature: 1. Left Gastro-omental/epiploic (Splenic)-largest artery 2. Right Gastro-omental (Gastroduodenal)-(Common Hepatic) -Anastomose -Also supply greater omentum Fundus: 1. Short Gastric (Splenic)
Duodenum Structure
Foregut/Midgut
Origin- immediately following stomach’s Pyloric region ( Superior 1st part Trans-Pyloric Plane = Intraperitoneal)
Descending 2nd: wraps around head of pancreas (RH of midline)
-Biliary tree goes through head of pancreas and enter 2nd Duodenum)
Inferior 3rd: back over midline. ontop of IVC and Aorta. underneath Superior Mesenteric Vessels.
Ascending 4th: Ascends to Duodenojejunal Flexure (L of midline)
2nd-4th= Retroperitoneal (against body wall)
1/2 duodenum = Transition to midgut (Blood, nerves, lymphatics change)
Duodenum Neurovascular and Lymphatic Supplies
- Superior 1/2:
a) Arterial: Superior Pancreatoduodenal branches (from gastroduodenal artery of coeliac origin)
b) ANS Nerves: Ceoliac Plexus T12
c) Venous: Portal Vein Directly
d) Lymphatic drainage: Pre-aortic Coeliac nodes T12 - Inferior 1/2:
a) Arterial: Inferior pancratoduodenal branches (from Superior Mesenteric origin) - ANS Nerves: Superior Mesenteric Plexus L1
- Venous: Superior Mesenteric Vein (SMV) (then forms portal vein)
- Pre-arotic Superior Mesenteric Nodes L1
Where is the location of Para-aortic nodes?
On the sides of the Kidney
What is the relationship between Biliary tree and Duodenum?
enters 2nd part of duodenum
1. Ampulla of Vater:
“ampulla” = Swelling in a tube
Union of Common Bile duct + Main Pancreatic Duct
- Major Duodenal Papilla:
“papilla”= nipple like process- where bile is released
Enters through wall of 2nd part of Descending Duodenum
Controls flow of: - Bile from Liver (emulsify fat for digestion)
- Pancreatic Juice from pancreas
into the Duodenum via Sphincter of Oddi
Sphincter of Oddi= circular muscular component - (Minor Duodenal Papilla sometimes present)- with accessory pancreatic duct (9% of duct)
Component Viscera of Midgut
Distal half of Duodenum Jejunum Ileum Caecum & Appendix Ascending Colon 2/3 Transverse Colon
Midgut Neurovascular and Lymphatic Supplies
Arterial: Branches of Superior Mesenteric Artery -abdominal aorta L1
Venous: Superior Mesenteric Vein
Nerves: Superior Mesenteric Plexus L1
Lymphatics: Pre-Aortic nodes L1 (superior Mesenteric Nodes)
-Pain referred to Umbilical region
Structural features of small intestine
Mid Gut
Long thin convuluted muscular tube - Increase SA
~6m long
Bulk of digestion
1. Jejunum 2/5th of length
2. Ileum 3/5th of length
Suspended from body wall via Mesentery
-Fan shaped folds of peritoneum enclosing gut tube
-allows ingress/egress of vessels, nerves, lymphatics
Identifying difference: Arterial Arcade Patterning
Jejunum: 1 or 2 arcades + long branches
Ileum: many arcades + short branches
Other Differences: width, mesenteric fat, lymphoid tissue
Small Intestine Neurovascular and Lymphatic Supply
Arterial: Branches of Superior Mesenteric Artery L1
-Jejunal arteries
-Illeal arteries
ANS Nervous supply: Superior Mesenteric Plexus L1
Venous: Superior Mesenteric Vein
Lymphatic Drain: Pre-aortic Superior Mesenteric nodes L1
Large Intestine Transition
Midgut/Hindgut 2/3 along Transverse Colon Pain referral: Midgut: Umbillical region Hindgut: Suprapubic region Ileocaecal Junction - Illeum entering Caecum= most proximal VeriformAppendix= remnant. Enlarged in rhueminant vegetarians(e.g. rabits) for bacteria. Regressed in humans- appendicitis: hanging on but not doing function, so infection tends to get trapped Sigmoid Colon= S-shaped 2x Flexures: 1. Right Hepatic Colic Flexure (lower due to liver) 2. Left Splenic Flexure (Higher as no imposing liver)
Function and general features of Large Intestine
Function:
-reabsorb water and electrolytes
-store undigested material until expelled by body (needs to be a large reservoir)
General Features:
1. Haustra - Sacculations/dilated of the wall -to store and increase SA for H2O reabsorption
2. Appendices Epiploicae - Fatty tags (none on small intestines). Proximal end/caecum. Can be inflamed/infected, mimic appendicitis. (in same region)
3. Teniae Coli - Longitudinal muscles collected into 3x bands (continuous with smooth muscle of small intestine)
4. Veriform Appendix: Own mesentery. Blind ended evolutionary tube.
Surface Anatomy of Large Intestine
Midgut/Hindgut
All regions except Umbilical
a) Caecum+Appendix (proximal): Right Groin
b) Hepatic Flexure: Right Hypochondrium (inferior to liver)
c) Splenic Flexure: Left Hypochondrium (anterior to spleen)
d) Sigmoid colon: Left Groin
Large Intestine Arterial Supply
- Superior MA L1
a) Caecum/Appendix: Caecal + Appendicular arteries respectively. (from Ileocolic loop- terminal artery which loops back on itself and anastomoses)
“colic” = colon
b) Ascending Colon: Right Colic artery
c) Proximal 2/3 Trans. Colon: Middle Colic + Marginal Artery - Inferior MA L3
a) distal 1/3 Transverse Colon: Marginal A + Left Colic a
b) Descending colon: Left Colic artery
c) Sigmoid colon: Sigmoid artery
-Marginal artery= Anastamotic point between Superior and Inferior Mesenteric Arteries
Marginal artery
Anastamotic point between Superior and Inferior Mesenteric Arteries
Descending/Sigmoid colon features on Barium Contrast Radiographs
Descending and Sigmoid Colon can often become muscularised
- resembles small intestine
- constriction
Rectum Structure
hindgut
Final storage Depot
Final transition area
Sigmoid Colon–>Rectum =L3
Sacrum: sits back on 45 degrees
Tip of cocyx= pierces pelvis diaphragm –> becomes Anal Canal
Retroperitoneal (no mesentery)
-Superior 1/3: Visceral peritoneum covering (anterior and lateral)
-Middle 1/3: peritoneum Anterior surface only
-Inferior 1/3: Infraperitoneal
Transverse Folds
Note: 1/3s apply to Blood supply + Lymphatics too
Rectum’s Neurovascular and Lymphatic Supply
- Superior 1/3:
a) Arterial: Superior Rectal branches of Inferior MA L3
b) Venous: Inferior MV - Portal vein
c) ANS Nervous supply: Inferior Mesenteric Plexus L3
d) Lymphatics: Pre-aortic nodes L3 - Medial and Inferior 1/3s:
a) Arterial:
- Medial 1/3 : Middle Rectal banch of Internal Iliac
- Inferior 1/3: Inferior Rectal branch of Internal Pudendal (branch of Internal Iliac)
b) Venous: Internal illiac - Common Iliac - IVC
c) ANS Nervous Supply: Inferior Hypogastic Plexus
d) Lymphatics: Internal Iliac Nodes
Venous Drainage. Portal system take nuterients to liver for detoxification. Everywhere else in body puts into IVC into heart and circulates around.
Venous drainage always follow Arterial flow
Superior1/3 = Portal
Inferior 2/3= Systemic system
Portal-systemic anastomosis (2/3)
-hypertension: hepatic hypertension/cirrhosis, backflow of blood (through portal), varices (in systemic system)
Portal system
Liver --> Portal Vein a) Splenic --> Inferior MV b) Superior MV celiac branches drain straight into portal Portal Vein L1 on Transpyloric plane
Autonomic Supply of Gut
Parasympathetic:
- Vagus (CN X) - in brainstem
- Pelvic Splanchnic nerves S2-4
Sympathetic:
1. Thoracic, Lumbar + Sacral Splanchnic nerves. From T5-L2 sympathetic ganglia (full sympathetic chain is T1, but involves cardiopulmonary + abdominal)
Control:
- Viscera, glands BV
- Smooth muscle
- Non-conscious control (automatic)
- Motor + Sensory
Sympathetic Chain and Nerves
Para-vertebral chain of Ganglia (either side of vertebral column)
T1-L2 output = splanchnic nerves
=Visceral nerve specifically. directly to Organs (not somatic or peripheral nerve)
= form Plexuses on Aorta, nerves travel with BV to organs (connection b/w arterial , venous and nervous supply)
Autonomic Supply of Gut
- Foregut: Celiac P. Greater Splanchinic T5-9. Vagus (X)
- Midgut: Superior Mes P. Lesser Splanchinic T10-11. Vagus (X)
- Aorticorenal: Renal P. Lesser Splanchinic T12. Vagus (X)
- Hindgut:
a) Inferior Mes P. + Superior Hypogastric P.
b) Lumbar L1-2 Splanchnic + Sacral S2-4 Spanchnic
- output of sympathetic chain is L1-2. therefore S2-4 are L1-2 branches which have travelled down chain. Dont get pain referral to S2-4 dermatomes
c) Pelvic Splanchn`ic S2-4 - Pelvic Organs. Inferior/Superior Hypogastric. Sacral Spanchnic S2-4. Pelvic Splanchnic S2-4.
Referred pain
Pain is referred back to the original spinal levels of the sympathetic supply via Afferent fibres and then via Dorsal root (along with somatic afferents)
Unlike somatic peripheral neres, there is No specific point of reference so pain os spread around the corresponding dermatomes:
Foregut: T5-9 (greater splanchnic).
-coeliac plexus. Cannot feel bowel moving. Only Stretch receptors (feel inflammation as Undirected message to brain. Pain to Epigastric region. borad/diffuse)
Midgut: T10-11 (lesser splanchnic) Umbilical region
Hindgut: L1-2 (Lumbar/sacral spanchnic) Suprapubic region (Deep pain in pelvis)
Appendicits
Enflamed appendix
Afferent sympathetic fibres refer to T10-11 dermatomes
1. Broad Diffuse pain in Umbillical region (stomach ache)
2. Appendix becomes so enflamed that contacts and presses on Parietal Peritoneal body wall. Parietal P contain somatic sensory nerves, intercostal nerves T7-12. pain localised in Lower Right Quadrant (pin-pointed to somatic nerves)
-Pain now felt as Acute & Localised
