Structure of intestines and anus Flashcards
Highest point of diaphragm
T8
Route faeces take from caecum to anal canal
Cecum - ascending - hepatic flexure - transverse colon - splenic flexure - descending colon - sigmoid colon - rectum - anal canal
What is the caecum?
Where large and small intestines join
Which part of the intestines does the superior mesenteric artery supply
Ascending and transverse
Which part of the intestine does the inferior mesenteric artery supply
Sigmoid colon, rectum, descending colon
Where does the midgut end?
Distal transverse colon
Relevance of middle colic artery
Anastomoses with inferior mesenteric artery
Where does all the blood from bowels end up?
Liver
Where does the superior mesenteric vein drain?
Midgut
What forms the hepatic portal vein?
Splenic vein + superior mesenteric
Where is the gasproduodenal artery?
Behind superior duodenum,
Why is it dangerous to have ulcer in superior duodenum?
If deep can erode gasproduodenal artery
Function of momentum
Separates abdomen into greater and lesser sacs
Paracolic gutter
fluid can travel along these which can run and collect in pelvis etc - infection could be from anywhere in abdomen
Anal canal histology
- Mucosa of anus folds longitudinally to form columns
- At the bottom of folds are pouches with anal valves
- Glands in pouches secrete mucus
- Dentate line separates endoderm (gut) from ectoderm
- Columnar epithelium above dentate line and stratified squamous epithelium below
Ischiorectal fossa
- Rectum supported by levator ani
- Transverse perineal fascia
- Ischiorectal fossa filled with fat - lateral border is ischial tuberosity
- Pudendal canal - contains pudendal nerve
- Pudendal nerve can be affected by abscesses
Which part of the duodenum is intraperitoneal?
Superior part
Where does duodenum start
L1
Relevance of duodenal papilla
Marks start of embryological mid-gut
4 parts of duodenum
- Descending: runs with IVC
- Superior: on a mesentery, gastroduodenal artery behind (bleeds a lot)
- Ascending: supported by ligament of Treitz - contraction closes duodenum
- Horizontal: superior mesenteric A and V run over anterior surface
SMA
SMA emerges superior to where L renal vein crosses abdominal aorta, will then continue to run anterior to horizontal duodenum
Jejunum vs ileum
- Jejunal loops are proximal and left of midline
- Ileal loops are inferior right part of abdomen and pelvis
- Jejunum = 4cm externally, internal diameter of 3cm
- Ileum = 3cm externally, 2.5cm internally
- Jejunum = more wall, less villi
- Ileum: thin wall, more villi
- Jejunum has 1-3 arterial arcades
- Ileum has 2-6 arcades
- Jejunum has fewer longer and thicker vasa recta
- Ileum has more shorter and thinner vasa recta
- Peyer’s patches - lymphoid tissue in luminal wall, cause bowel intussesception in kids
- Jejunum has fewer peyer’s patches but they are distal
- Ileum has more peyer’s patches but they are throughout its length
COlon
- Composed of appendix, caecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anus
- Most water redigested from chyme here
Appendicitis
Pain in midline to RIF
