Abdominal Midgut and Hindgut Flashcards
What makes up the midgut?
the jejunum, the ileum, the cecum, the ascending colon, and the transverse colon
what makes up the hindgut?
the descending colon, the sigmoid colon, and the rectum and anus
what type of organ is the jejunum?
intraperitoneal- it is supported by the mesentery
what does the jejunum and the ileum contain?
mucosal folds called plicae circulares
what is the arterial supply of the jejunum?
it is supplied by arterial arcades with long vasa recta (straight arteries) off branches of the SMA
what type of organ is the ileum?
intraperitoneal- it is supported by the mesentery
what is the arterial supply of the ileum?
it is supplied by compound arterial arcades with short vasa recta (straight arteries) branches of SMA
where does the colon begin?
at the ileocecal junction
what are the external features of the colon?
3 outer bands of longitudinal smooth muscle (tenia coli)
what do the tenia coli cause?
outpocketings (haustra) with attached outer fatty appendages (appendices epiploicae)
what is the blind pouch of the colon that contain ileal papilla?
cecum
what are ileal papilla?
cone-like projections of the ileum
what valve regulates the passage of ileal contents into the cecum?
ileocecal valve
what type of organs are the ascending and descending colon?
secondarily retroperitoneal
what type of organ is the transverse colon?
intraperitoneal
what is the transverse colon suspended to the posterior wall by?
transverse mesocolon mesentery
what is the sigmoid colon suspended by?
sigmoid mesocolon
where is the appendix attached to?
posterior-medial part of the cecum
what is the appendix supported by?
mesoappendix
what does the appendix contain?
several lymphoid nodules
what type of organ is the rectum?
retroperitoneal and sub-peritoneal
what does the rectum contain?
3 transverse rectal folds/rectal valves (superior, middle, and inferior)
what is the rectum continuous with?
the anal canal
what is the anal canal surrounded by?
2 anal sphincters
what is the internal anal sphincter comprised of?
smooth muscle
what is the external anal sphincter comprised of?
skeletal muscle
what does the anal canal contain?
anal columns, anal valves, and anal sinuses
in the anal canal, what is the transition point of the different epithelium known as?
pectinate line
what does the epithelium transition from in the anal canal?
it transitions from columnar epithelium to nonkeratinized squamous epithelium
what is the external opening of the anal canal known as?
anus