PMDC NEB Step-1 (Review of abdominal contents)-day-7

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