M104 T1 L2 Flashcards
Which the three layers start to develop in the gastrula in embryology?
ectoderm
mesoderm
endoderm
What part of the digestive tract does the ectoderm develop into in embryogenesis?
epithelium at extremities of tract (cranial and caudal)
What part of the digestive tract does the mesoderm develop into in embryogenesis?
muscular layers
What part of the digestive tract does the endoderm develop into in embryogenesis?
majority of gut, including most of epithelium and glands of digestive tract
What are examples of areas where epithelium is present?
skin
the lining of the alimentary tract
What are the cranial and caudal ends of the body that are lined by the epithelium?
cranial - the oral cavity
caudal - the anal canal
How does the primitive gut develop?
the gastrula folds twice
at 4 weeks, the cranial and caudal ends are still closed by two membranes
How does the gastrula fold when forming the primitive gut?
first, it folds in a cranial-caudal (head to tail)
it then folds laterally (side to side)
What are the membranes that keep the ends of the gastrula shut at 4wks?
Bucco-pharyngeal (cranially)
Cloacal (caudally)
What are the three divisions of the digestive tract?
Foregut
Midgut
Hindgut
What structures are contained in the foregut?
Oesophagus Stomach Proximal half Duodenum Liver Pancreas
What structures are contained in the midgut?
Distal half duodenum Jejunum Ileum Cecum Ascending & ¾ Transverse Colon
What structures are contained in the hindgut?
¼ Transverse Colon
Descending Colon
Sigmoid Colon
rectum
What structure is the primitive gut held in position by?
mesenteries (a structure of mesodermal origin)
How does the mesentery hold the digestive tract of the primitive gut in position?
it anchors it to the posterior abdominal wall
What are the two layers of the peritoneum?
parietal (superficial)
visceral (deep)
What is in between the parietal and visceral peritoneums?
peritoneal cavity
What will the peritoneal cavity eventually contain?
peritoneal fluid
What are the roles of the mesentry?
to suspend and support the instestines
works as a pathway for all of the vessels that are going to supply the alimentary track
Why does gut rotation occur?
unclear cause
In what ways does gut rotation occur?
by constriction of the duodenum
by midgut volvulus
What are the effects of midgut volvulus on the gut?
ischaemia
necrosis
possibly death
What are the common symptoms of midgut volvulus?
Vomiting
Pain
Abdominal distention
Why does midgut volvulus cause necrosis and or ischaemia in the gut?
the gut is being twisted off from any blood supply, so the tissue dies
What causes vomiting in midgut volvulus?
because the gut has been twisted off, the passage is obstructed
so food coming one way has to go back the way it came
What causes pain in midgut volvulus?
the nerves travelling through these mesenteries are being constricted which causes pain
Which structures does the dorsal mesentry give rise to?
Gastrosplenic ligament
Lienorenal ligament
Greater omentum
Mesentery of SI & LI
Where does the ventral mesentery degenerate?
in the lower portions from the midgut and areas following on
Where does the ventral mesentery persist after development?
in the foregut
What structures does the ventral mesentery in the foregut develop into?
Ligaments around the liver
Falciform ligament
Lesser omentum
What is the abdominal wall made out of?
anteriorly - external abdominal muscle
posteriorly - lumbar vertical column
What muscles make up the three layers that make up the sides of the abdominal wall?
external oblique
internal oblique
transversus abdominus muscle
What direction does the external oblique muscle run in?
antero inferiorly
hands in coat pockets
What location in surface anatomy does the external oblique muscle start from?
they begin from the outer surface of your lower 8 ribs and then move
Where does the external oblique muscle extend down to?
linea alba
iliac crest
pubic tubercle
Where does the inguinal ligament attach to?
the pubic tubercle
What is the difference between the shape of most tendons and that of the oblique aponeurosis?
tendons - look like a bundle of fibres
apo - flat sheet spanning a wide area