Anatomy(The Abdomen, Pelvis and Perineum) Flashcards
Gut developed from what
Primitive endodermal tube
Parts of gut with blood supply
divided into three parts:
• foregut: extends to the entry of the bile duct into the
duodenum (supplied by the coeliac axis)
• midgut: extends to distal transverse colon (supplied by
superior mesenteric artery)
• hindgut: extends to ectodermal part of anal canal (sup-
plied by inferior mesenteric artery).
Rotation of stomach with vagus
Clockwise rotation seen from above
• Rotates so that the right wall of the stomach now
becomes its posterior surface, forming the lesser sac
behind.
• Vagus nerves rotate with the stomach so that the right
vagus nerve becomes posterior and the left anterior.
Peritoneal relation of duodenum
all retroperitoneal.except 1st inch
What is vitellointestinal duct
the vitelline duct, also known as the vitellointestinal duct, the yolk stalk, the omphaloenteric duct or the omphalomesenteric duct is a long narrow tube that joins the yolk sac to the midgut
yolk sac?
yolk sac is far more widely used. In humans, the yolk sac is important in early embryonic blood supply and much of it is incorporated into the primordial gut during the fourth week of embryonic development.
During development position change of caecum
The caecum descends into its definitive position in the
right iliac fossa, pulling the colon with it.
Relation of peritoneum with mesentery
•As the stomach rotates clockwise the duodenum
swings to the right, its mesentery fusing with the peri-
toneum of the posterior abdominal wall
•The mesenteries of the ascending and descending colon blend with the posterior abdominal wall, except for the
sigmoid colon, which retains a mesentery.
Mechanism of gut atresia or stenosis
In early fetal life, growth obliterates the lumen of the
developing gut. It then recanalizes. If recanalization is
incomplete, areas of atresia or stenosis may result.
What is Meckel’s diverticulum?
The communication between the primitive midgut and yolk sac may persist as a Meckel’s diverticulum attached to the back of the umbilicus by a fibrous cord, a remnant of the vitellointestinal duct (this may act as a fixed point for small bowel volvulus).
What is peritoneal band of Ladd
The caecum may also be free and may
obstruct the second part of the duodenum because of
peritoneal bands (of Ladd) passing across it. The base
of the mesentery is then very narrow as it is not fixed
at either end, and the whole of the midgut may twist
around its own blood supply, i.e. volvulus neonatorum.
*A peritoneal band of Ladd, also known as a Ladd’s band or mesenteric attachment, is a fibrous band of tissue that can form in the peritoneum during fetal intestinal rotation errors. The band can stretch from the caecum to the subhepatic region and usually attaches the caecum to the retroperitoneum in the right lower quadrant. Ladd’s bands are the most common type of peritoneal band that can cause intestinal malrotation.
What is exomphalos?
Persistence of midgut herniation at the umbilicus may
occur after birth
Exomphalos vs Gastroschisis
The prefix “ex-“ is a Latin word that means “out of,” “from
*Exomphalos/omphalocele
abdomen doesn’t close around the umbilical cord allowing organs to protrude into the the cord.
*Gastroschisis
defect in the abdominal wall to the side of the umbilical cord, usually the right side.
#The word omphalocele comes from the Greek words omphalos, which means “umbilicus”, and cele, which means “cavity”
#The word “gastroschisis” comes from the Greek words gastro, meaning “stomach”, and schisi, meaning “split”.
Function of urorectal septum
Urorectal septum divides the cloaca into bladder anteri-
orly and rectum (hindgut) posteriorly.
• At its caudal end, the urorectal septum reaches the cloa-
cal membrane and divides it into anal and urogenital
membranes.
• The anal membrane separates the hindgut from the
proctodeum (anal pit).
• Eventually the anal membrane breaks down and conti-
nuity is established between the anal pit and the hindgut.
• Failure of the anal membrane to rupture or anal pit to
develop results in imperforate anus.
Formation of anal canal
Anal canal develops from the end of the hindgut (endo-
derm) and an invagination of ectoderm, the proctodeum.
What is urachus
The connections between cloaca (rudimentary bladder) and allantois. The urachus is the embryonic remnant of this connection.
What is urachus
The connections between cloaca (rudimentary bladder) and allantois. The urachus is the embryonic remnant of this connection.
What gives off epididymis and vas
• Mesonephros develops at the 4th week; this also degenerates but its duct persists in the male to form the epididymis and vas deferens.
Metanephros gives off what
proximal part of the tubular system and glomeruli which are developing from the metanephros
Convention of metanephros and metanephric duct
• Metanephros develops at the 5th week in the pelvis.Metanephric duct arises as a diverticulum from the
lower end of the mesonephric duct.
• Metanephric duct (ureteric bud) invaginates the metanephros, undergoing repeated branching to develop into the ureter, pelvis, calyces and collecting tubules.
Migration of kidney
• The kidney develops in the pelvis, eventually migrating upwards, its blood supply moving cranially with it, initially being from the iliac arteries and eventually from the aorta.
What is ureteric bud
Metanephric duct
Mechanism of forming polycystic kidney
• Failure of fusion of the derivatives of the ureteric bud with the derivatives of the metanephros may give rise to autosomal recessive form of polycystic kidney.
Ureteric cause of urinary incontinence
• The ureteric bud may branch early, giving rise to double ureter. Rarely, the extra ureter may open ectopically into the vagina or urethra, resulting in urinary incontinence.