Session 2 Flashcards
When does development of the primitive gut tube begin
Week 3
What 2 layers does the mesoderm split into in the gut
Somatic- develops into the abdominal wall
Splanchnic- smooth muscles of the gut
What is the space between the splanchnic and somatic mesoderm
Coelomic cavity- pre cursor to pleural cavity and peritoneal cavity
What are omenta
Specialised regions of peritoneum
-the greater omentum is derived from the dorsal mesentary
How do the greater and lesser sacs form
Rotation of the stomach
What gives passage to folds and reflections that suspends the gut
The dorsal and ventral mesenteries
How is the oropharyngeal membrane and hind gut at the cloacal membrane
Closed but when the membranes break down, the gut becomes open to the exterior at the future mouth and anus
What are retroperitoneal structures
Structures that are not suspended within the peritoneal cavity
Why does the stomach have its distinct curvature
When the dorsal border develops it develops faster
How is the liver divided into 2
It grown into the ventral mesentery dividing it into 2 parts- the falciform ligament and lesser omentum
What is a hernia
A protusion of part o the abdominal contents being the normal confines of the abdominal wall
What does a hernia consist of
Sac, contents and coverings
What is the inguinal canal
An oblique passage through the Lowe abdominal wall predominantly composed of layers from the antrolateral abdominal muscles
What is the anterior wall mainly composed of
Aponeurosis of external oblique
what forms the floor of the inguinal canal
Inguinal ligament and lacunar ligament medially
Roof if inguinal canal
Arching fibres of internal oblique and transersus abdominus
Posterior wall of inguinal canal
Composed of transversalis fascia and conjoint tendon medially
What are the mos common abdominal wall hernias
Indirect Inguinal hernias and leave the abdominal cavity in the inguinal region
Are inguinal hernias more common in males or females
Males
Where do indirect hernias exit deep inguinal ring and pass into
the inguinal canal to variable distance some Pass through the scrotum
Where do direct inguinal hernias pass
Directly through the abdominal wall in a area of potential weakness called the Hesselbach’s triangle
How do indirect and direct hernias relate to the inferior epigastric muscles
Indirect pass laterally to them direct pass medially
Are femoral hernias more common in women or men
Women
Where do femoral hernias passs
Femoral Canal
What happens if processus vaginalis doesnt close
Risk of hernias in the inguinal canal
What happens if processus vaginalis doesnt close
Risk of hernias in the inguinal canal
What is a omphalocele
Failure of the midgut to return to the abdomen during development
Gastroschisis
Defect in ventral abdominal wall
Abdominal viscera not covered in peritoneum- exposed to amniotic fluid
Umbilical hernia
Hernia bulge at the site of umblicus
Para-umbilical hernia
Goes through linea alba in region of umbilicus
symptoms of hernia
Vomiting
Sepsis
Pain
inCarcerated hernia
Stuck
Stranguated
Blood supply is disrupted leading to necrosis
What do the paraxial mesoderm form
Skeletal muscle
Vertebra
Cartilage
What does the intermediate mesoderm go onto form
Kidneys
Gonads
What does the ectoderm go onto form
Nerve tissue
Epidermis
What does the foregut form
Oesophagus to 2nd part of duodenum where bile duct joins
whAt does the mid gut go onto form
Distal duodenum to proximal transverse colon
What does the hindgut go onto form
Distal 2/3 transverse colon to upper anal canal
What is the Vitelline duct
Connects the midgut to the yolk sac
Splanchnopleuric mesoderm
Combination of endoderm and splanchnic portion of mesoderm
Somatopleuric mesoderm
Combination of somatic mesoderm and endoderm
What is the intraembryonic coelom
Space between somatipleuric and splanchnopleuric mesoderm which gives rise to the abdominal and thoracic cavity
What is a vittelibe cyst
When there is a small swelling
what is a vitteline fistula
When the vitteline duct is completely intact
What is included in the hind gut
Distal 1/3 transverse colon Descending colon Sigmoid colon Rectum Superior anal canal Bladder epithelia
What connects teh lesser sac to teh greater sac
Foramen of Winslow
What gut related landmark marks the start of the midgut?
The point at which the common bile duct and major pancreatic duct enter the duodenum
Once fully developed, what is the relative position of the small and large bowel sections of the
midgut?
The large bowel lies to the right of the small intestine
Transverse colon lies superior to proximal small bowel
During the embryology of the gut, what does the cranial portion of the intestinal loop develop into?
small intestine
If the Caecum did not ‘descend’ during development of the midgut, where would it lie with the
abdominal cavity?
under the liver
right upper quadrant
If there is a problem during the physiological herniation of the midgut, and it undergoes a single 90-
degree clockwise rotation (as viewed from the front), the final layout of the gut will be different to
normal. Briefly describe this difference.
Transverse colon will lie behind the proximal small bowel, instead of in front of it
Why are there often more problems with the development of the intestines in Gastroschisis than with
an omphalocoele?
With a gastroschisis (a defect in the formation of the anterior abdominal wall) the intestines are not covered in
a layer of peritoneum and so are exposed to the amniotic fluid. This stunts their development. With an
omphalocoele the intestines are covered in peritoneum inside the umbilical cord (not exposed to amniotic
fluid).
. How rotation of the midgut during development results in the transverse colon lying
superior to the duodenum?
The initial layout of the intestinal loop involves cranial and caudal segments
The cranial section (superior section) develops into the small intestine and the caudal
section (inferior section) develops into the large intestine
There follows a series of three 90-degree counter clockwise (as viewed from the front)
rotations of the gut (while it is herniated)
This brings the caudal section initially to the left (1st rotation), then superior (2 rotation) and then to the right (3rd rotation)
Having followed this rotation the large intestine that develops from the caudal part of the intestine loop has been dragged over the top of the small intestine (and duodenum) and then to the right.
