pmdc neb step-1 (review of abdominal contents)-day-7
TRANSCRIPT
Review of Abdominal
Contents
Prof. Saeed Shafi
Learning Outcomes
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3
Quadrants of Abdomen
PARACENTESIS OF ABDOMINAL CAVITY
12
Vertical disposition of peritoneum
ATTACHMENT OF MESENTERIES
EXTRA-EMBRYONIC COELOM
2nd week1st week
INTRA-EMBRYONIC COELOM
3rd week
INTRA-EMBRYONIC COELOM
Pericardial cavity
Pleural cavity
Peritoneal cavity
IEC
EEC
PERICARDIAL CAVITY
INTRA-EMBRYONIC COELOM
HeartPeritoneal
cavity
Pericardial
cavity
Pericardioperitoneal
canal
PERITONEAL CAVITY
PERICARDIO-PERITONEAL CANALS
Pericardio-
peritoneal
canal
Pericardial cavity
PERITONEAL CAVITY
(Liver)
PERITONEAL CAVITY
(Umbilicus)
PERITONEAL CAVITY
(Hindgut)
PLEURO-PERITONIAL MEMBRANES
Pleural cavityBronchial Buds
DEVELOPMENT OF STOMACH(W4)
ROTATION OF STOMACH
ROTATION OF STOMACH
W5
LIVER
LIVER
W8
DEVELOPMENT OF Liver
ROTATION OF DUODENUM
The Gastro-intestinal Tract
• Hollow muscular tube that transports food &
liquid to the stomach
• Extends from pharynx to stomach
• Follows curve of vertebral column
• Pierces diaphragm at level of T10 vertebra
• Covered anteriorly & laterally in abdomen by
peritoneum= retroperitoneal
• Arterial supply
inferior phrenic artery
left gastric artery
• Venous drainage
left gastric vein
OESOPHAGUS
PARTS OF STOMACH
Angular notch : along lesser curvature; junction of body & pyloric part
Cardia : around opening of oesophagus
Fundus : dilated superior part - related to left dome of diaphragm
Body : between fundus & pyloric antrum
Pyloric part : has 2 parts - pyloric antrum & pyloric canal
Intestinal mucosa bears :
• transverse folds =
plicae circulares
• small projections =
intestinal villi
• both increase surface
area for absorption
• each villus contains a
terminal lymphatic
called a lacteal
PARTS OF SMALL INTESTINEExtends from pylorus to ileocaecal junction
Includes duodenum, jejenum, ileum
Small intestine plays primary role in digestion & absorption of nutrients
FIRST PART OF SMALL INTESTINE : DUODENUM
• Shortest, widest, most fixed part
• Has C-shaped course around head of pancreas
• Begins at pylorus; ends at duodenojejunal
junction
ARTERIAL SUPPLY
• Superior pancreaticoduodenal artery
(coeliac trunk)
• Inferior pancreaticoduodenal artery
(superior mesenteric artery)
VENOUS DRAINAGE
• Follow arteries - drain into portal vein
• Bile & pancreatic ducts enter its posteromedial
wall
• Duodenojejunal flexure : Junction of duodenum
& jejunum
• Begins as a pouch inferior to terminal portion of ileum
• Ends at anus
Functions :
1. Reabsorb water, compact feces
2. Absorb vitamins liberated
by bacteria
3. Store fecal material before
defecation
LARGE INTESTINE : FUNCTIONS
3 components viz.
1. CECUM
• Collects, stores chyme
• Ileocecal valve opens into it
2. COLON
• Bears haustra, taeniae coli, epiploic
appendages
• Subdivided into 4 regions
ascending
transverse
descending
sigmoid
• Terminates in anorectal canal
PARTS OF LARGE INTESTINE
3. RECTUM
• Leads to anus
• Muscular sphincters control passage of
fecal material to anus
PARTS OF LARGE INTESTINE: CAECUM
• First part of large intestine
• Continuous with ascending
colon
• Lies in iliac fossa
• Does not have a mesentery
• Has vermiform appendix
attached inferior to ileocaecal
junction
• Appendix has short triangular
mesentery = mesoappendix- that
suspends it from mesentery of
terminal ileum
PARTS OF LARGE INTESTINE: ASCENDING COLON
• Passes superiorly from caecum on
right side of abdominal cavity to
liver, turns to left as right colic
flexure
• Lies retroperitoneally along side
posterior abdominal wall
• Covered with peritoneum anteriorly
& on its sides
• Separated from anterior abdominal
wall by coils of small intestine &
greater omentum
PARTS OF LARGE INTESTINE: TRANSVERSE COLON
• Largest, most mobile part
• Crosses abdomen from right
colic flexure to left colic
flexure - bends inferiorly to
become descending colon
PARTS OF LARGE INTESTINE: DESCENDING COLON
Passes retoperitoneally from left
colic flexure into left iliac fossa,
becomes continuous with sigmoid
colon
PARTS OF LARGE INTESTINE: SIGMOID COLON
S-shaped loop - variable in length, links descending colon & rectum.
Extends from pelvic brim to 3rd segment of sacrum where it joins rectum
ACCESSORY DIGESTIVE ORGANS
• Liver
• Gallbladder
• Pancreas
• Hollow muscular
organ
• Stores & concentrates
bile
• Has fundus, body,
neck
GALLBLADDER
• Has head, body, tail
• Pancreatic duct
penetrates wall of
duodenum
• Pancreas is an
exocrine & endocrine
organ
PANCREAS
Exocrine functions:
* Secreting H2O
* Secretes ions
* Digestive enzymes into small intestine
Portal circulation
Sites of portosystemic anastomosis
June 2, 2015
DEVELOPMENT OF MIDGUT
June 2, 2015
• The umbilicus of a newborn infant failed to heal normally. It was swollen and there was a persistent discharge from the umbilical stump.
• A sinus tract was outlined with radio-opaque oil during fluoroscopy.
• The tract was resected on the 9th day after birth and its distal end was found to terminate in a diverticulum of the ileum.
June 2, 2015
• The umbilicus of a newborn infant failed to heal normally. It was swollen and there was a persistent discharge from the umbillical stump. A sinus tract was outlined with radiopaque oil during fluoroscopy. The tract was resected on the ninth day after birth and its distal end was found to terminate in a diverticulum of the ileum.
What is the embryological basis of the sinus tract?
What is the usuall clinical name given to this type of ileal diverticulum?
Is this anomaly common?
June 2, 2015
• An infant was born with a light gray, shiny mass measuring the size of an orange and protruding from the umbilical region at the time of birth.
• The mass was covered by a thin transparent membrane.
June 2, 2015
• A newborn infant had a light gray, shiny mass measuring the size of an orange and protruding from the umbilical region. The mass was covered by a thin transparent membrane.
What is this congential anomaly called?
What is the origin of the membrane covering the mass?
What would be the composition of the mass?What is the embryological basis of this protrusion?
Learning Objective
To discuss development of primitive gut andembryological basis of various congenital anomaliesof midgut
SPECIFIC OBJECTIVES
To describe the
– development of Midgut loop
– Derivatives of midgut loop
– rotation and positional changes
– Factors responsible for normal & defective rotation
– Anomalies due to malrotation of midgut loop
DERIVATIVES OFENDODERM
contributes to develop epithelium and glands of gut.
MESODERM
development of smooth muscles, connectives
tissue, blood vessels, lymphatics and serosa
NEURAL CREST CELLS
parasympathetic ganglia
SOURCES OF GUT DEVELOPMENT
Duodenum (distal to bile duct)
Jejunum
Ileum
Cecum
Appendix
Ascending colon
Transverse colon
June 2, 2015
DERIVATIVES OF CRANIAL LIMB OF MIDGUT LOOP
Cranial limb grows rapidly and forms smallintestine, which returns first and occupiescentral position in abdomen:
Duodenum (distal to bile duct)
Jejunum
Ileum (proximal to Meckel’s diverticulm)
June 2, 2015
DERIVATIVES OF CAUDAL LIMB OF MIDGUT LOOP
Caudal limb undergoes little change except for cecal diverticulum formation:
Ileum (distal to Meckel’s diverticulm)
Cecum
Appendix
Ascending colon
Transverse colon
Early 6th Week
Midgut rotates 900 counter clock-wise within umbilical cord
during herniation.
Cranial limb becomes Right & caudal limb becomes left
10th Week
Midgut rotates 90+90=1800 counter clock-wise during reduction of hernia
Right limb becomes caudal
Left limb becomes cranial
11th week & Late fetal period
Midgut rotates 90+90=1800 counter clock-wise during
reduction of hernia
Cranial limb becomes Right & caudal limb becomes left
Midgut rotates 90+90+90=2700 counter clock-wise during reduction
of hernia
June 2, 2015
Fixation of Intestine
• Phyysiological Umbilical Herniation in 6th week
• 900 counter clockwise rotation during herniation (around axis of SMA)
• Reduction of Midgut herina in 10th week
• 1800 counter clockwise rotation (around axis of SMA) during reduction of hernia
• Mesentry of small intestine refixed obliquely
• Dorsal mesentry lost for ascending colon
June 2, 2015
Development of Cecum & Appendix
6 Week 8
Week
12
Week
At Birth Adu
lt
DEVELOPMENT OF MIDGUT
Mix RotationNon Rotation
Reverse Rotation
Subhepatic Cecum Internal Hernia Volvulus of Cecum
MECKEL’S DIVERTICULUM
June 2, 2015
Take Home Message ?
• Midgut loop & its derivatives
• Umbilical Herniation (6W)&reduction(10W)
• 2700 rotation of Midgut loop (around axis of SMA)
• Fate of ventral & dorsal mesentery
• Development of Cecum&Appendix
• Anomalies of midgut loop– Left sided colon/ mixed rotation/reverse rotation/ Volvulus
– Meckel diverticulum (vitelline cyst, sinus & fistula)
– Congenital Omphalocele / Umbilical Hernia / Gastroschisis
– Stenosis / Duplication of intestine
Case 11-3
A female infant was born with a small dimple where the anus should have been.Examination of the infant’s vagina revealed meconium and an opening of a sinus tract in the posterior wall of the vagina.Radiographic examination using a contrast medium injected through a tiny catheter inserted into the opening revealed a fistulous connection with the lower bowel.
• With which part of the lower bowel would the fistula probably be connected?
• Name this anaomaly
• What is the embryologic basis of this condition?
Objectives
What is Hindgut ?
How cloaca is transformed into urogenital sinus and anorectal canal?
What is urorectal septum ?
Difference between low and high anal anomalies?
DERIVATIVES OF HINDGUT
•Splenic flexure of colon
•Descending colon
•Sigmoid colon
•Rectum
•Upper 2/3rd anal canal
•Urogenital sinus
Anorectal canal
DERIVATIVES OF CLOACA
•Cloaca is the distal dilated end of hindgut
• ventrally it is connected to a finger like diverticulumallantoise
• Partitioning of cloaca (W 5 – 7) by urorectal septum into
• urogenital sinus (anterior)
• anorectal canal (posterior)
•Partitioning of cloacal membrane into • anal and urogenital membrane
•Partitioning of cloacal sphincter into • external anal sphincter and urogenital sphincter
•Parineal body is at the site of intersection of anal membrane and urorectal septum
DEVELOPMENT OF ANAL CANAL
•Upper 2/3rd (endodermal) from hindgut
•Lower 1/3rd (ectodermal) from proctodeum
•Junction between these is at the level of pectinate line / anal valves / anal membrane
• Innervation & blood supply of anal canal
DEVELOPMENT OF ANAL CANAL
DEVELOPMENT OF ANAL CANAL
DEVELOPMENTAL ANOMALIES
Low annorectal anomalies (imperforate anus / ectopic
anus, anal agenesis, Persistent cloaca etc)
High anorectal anomalies (with or without fistulae)
Anal agenesis with perineal fistula
Ano-rectal agenesis with recto-vaginal fistula
Anorectal agenesis with recto-uretheral fistula
Take on Message
What is Hindgut ?
How cloaca is transformed into urogenital sinus and anorectal canal?
What is urorectal septum ?
Difference between low and high anal anomalies?
Portal circulation
Hepatic portal system
• Sites of porto-systemic anastomosis
• Portal hypertension and its causes?
• Surgical interventions for portal hypertension
Tributaries of Portal Vein
• Superior Mesenteric Vein
• Splenic vein
• Right Gastric Vein
• Left Gastric Vein
• Prepyloric Vein
• Superior Pancreaticuduodenal Veins
• Cystic Veins (drains into right branch of portal vein)
• Paraumbilical Veins (drains into left branch of portal vein)
Portal circulation
Anal
Musosa