Gastrointestinal Anatomy Flashcards
Where is the GI derived from?
Endoderm
What gives rise to the esophagus, stomach, proximal half of the duodenum, liver, gallbladder, and pancreas?
The foregut
What gives rise to the distal third of the transverse colon to the proximal half of the anal canal?
The hindgut
What gives rise to the distal half of the duodenum, small intestine, proximal half of large intestine up to the proximal 2/3 of transverse colon?
The midgut
How often does Meckel’s diverticulum occur? Where does it occur?
2%; 2 feet proximal to the ileocecal junction
What region of the abdomen contains the stomach, duodenum, and pancreas?
Epigastric
What region of the abdomen contains the kidneys?
Right and left flank
What region contains of the abdomen liver and gallbladder?
Right hypochondrium
What region of the abdomen contains the bladder and uterus?
Hypogastric
What region of the abdomen contains only the small intestine?
Umbilical
What region of the abdomen contains the left ovary, left uterine tube, and sigmoid colon?
Left iliac fossa
What region of the abdomen contains the spleen?
Left hypochondrium
What region of the abdomen contains the appendix, right ovary and right uterine tube, and cecum?
Right iliac fossa
What dermatome innervates the level of the xiphoid process?
T7
What dermatome innervates the level of the umbilical region?
T10
What dermatome innervates the level of the inguinal region?
L1
What is immediately below skin in the anterior abdominal wall?
Subcutaneous tissue
What is the outer layer of the subcutaneous abdominal tissue is continuous with the fatty subcutaneous layer of the rest of the body?
Camper’s fascia
What layer of subcutaneous fascia is present only in the lower abdomen?
Membranous or Scarpa’s fascia
What does scarpa’s fascia continue as?
Colles fascia in the scrotum and Buck’s fascia in the penis
What is the lateral edge of the rectus sheath?
Linea semilunaris
What three structures are medial to the linea semilunaris?
Anterior layer of the rectus sheath
Rectus abdominis muscle
Posterior layer of the rectus sheath
Other than skin, subcutaneous fascia, and muscle, what are the remaining 3 layers?
Transversalis fascia, extraperitoneal fat, and parietal peritoneum
What levels of innervation supply the abdominal wall?
T7-11, subcostal T12, and Iliohypogastric/ilioinguinal L1
What forms the anterior layer of the rectus sheath above the arcuate line?
External oblique aponeurosis
Anterior layer of the internal oblique aponeurosis
What forms the posterior layer of the rectus sheath above the arcuate line?
Posterior layer of the internal oblique aponeurosis
Aponeurosis of transversus abdominus
What forms the anterior layer of the rectus sheath below the arcuate line?
The aponeurosis of the internal and external oblique and the aponeurosis of the transversus abdominus
What forms the posterior layer of the rectus sheath below the arcuate line?
Only the the transversalis fascia
Where is the arcuate line located?
Posterior to the rectus muscle midway between the umbilicus and the symphysis
What is the peritoneum?
Inner lining of the abdominal cavity
What are the layers of the peritoneum?
Parietal and visceral
What layer of the peritoneum is sensitive to distension?
Visceral
What layer of the peritoneum is sensitive to pain?
Parietal
What compartment of the abdominal cavity lies behind the stomach?
Lesser sac
What separates the greater and lesser sac of the abdominal cavity?
The epiploeic foramen of Winslow
What structures are retroperitoneal?
Ascending colon, descending colon, pancreas, adrenals, rectum (lower 2/3s), kidney, aorta, IVC, duodenum (2nd to 4th parts)
What type of epithelial cell lines the stomach?
Columnar epithelial
From outside to inside, what are the layers of smooth muscle arrangement around the stomach?
Longitudinal
Circular
Oblique
What two folds of peritoneum attach two the stomach?
Greater and lesser omenta
What type of stomach cell secretes pepsinogen?
Chief cells
What do parietal cells, of the stomach, secrete?
HCl, Intrinsic factor
What are the vessels that supply the stomach?
Left gastric (from celiac trunk) Right gastric (from common hepatic) Left gastro-epiploic and short gastric (from splenic) Right gastro-epiploic (from gastro-duodenal of common hepatic)
What is the c-shaped portion of the small intestine that wraps around the head of the pancreas?
Duodenum
How many parts does the duodenum contain? What are they?
4, superior, descending, horizontal, ascending
The upper half of the duodenum is supplied by what artery?
Superior pancreaticoduodenal artery
The lower half of the duodenum is supplied by what artery?
Inferior pancreaticoduodenal artery
The common bile duct opens into which portion of the duodenum?
2nd
What passes over the third part of the duodenum?
Superior mesenteric vein and artery
What ligament holds the duodeno-jejunal junction in place?
The suspensory ligament (of Treitz)
What portion of the duodenum is intraperitoneal?
The first inch
What forms the common hepatic duct?
Right and left hepatic ducts
What forms the common bile duct?
Common hepatic and cystic duct
What is the triangle between the cystic duct, common hepatic duct, and liver?
Callot’s triangle
What passes through Callot’s triangle?
Cystic artery
What does the common bile duct travel with?
The proper hepatic artery and portal vein along the free edge of the lesser omentum
What does the gallbladder store?
Bile (50cc)
What is the structure of the gallbladder?
Fundus, body, neck, and cystic duct (of Heister)
What is more vascular portion of the small intestine?
Proximal (jejunum)
What is the thinner, narrower portion of the small intestine?
Distal (ileum)
Which portion of the small intestine contains more fat and more vasa recta and arcades?
Ileum
What are peyer’s patches?
GALT in the ileum
What supplies the small intesting, and large intestine up to the proximal 2/3s of the small intestine?
Superior mesenteric artery
What features separate the large intestine from the small intestine?
Haustra, teniae coli, appendices epiploica, and larger diameter
What are sections of the large intestine?
Cecum, ascending, descending, and sigmoid
What is the most common location of the appendix?
Behind the cecum/retrocecal
What other locations may the appendix be in?
In the pelvis, retro-ileal or pre-ileal
What supplies the appendix?
The appendicular artery
What is the point at which the base of the appendix is located?
McBurney’s point 2/3 along a line from the ASIS to the umbilicus
What is the watershed area of the large intestine?
The point at where the large intestine switches from midgut to hindgut origins
What is the importance of the watershed area?
Blood supply can be compromised during hypovolemic shock
What is the path of lymph nodes that drain the colon?
Pericolic to paracolic to mesenteric to para-aortic
The rectum has how many curves?
3, two left, one right
What is the lower dilated portion of the rectum?
Ampulla
What is the pattern of peritoneal covering of the rectum?
The upper third is covered on the anterior and lateral sides
The middle third is covered by peritoneum on the anterior aspect
The last third is entirely retroperitoneal
What supplies blood to the rectum?
The superior rectal branch of the inferior mesenteric artery
What drains the lymphatics of the rectum?
Inferior mesenteric nodes
What demarcates the rectum and anal canal?
The pelvic diaphragm
What is the embryological derivative of the anal canal?
Endoderm and ectoderm
What is the junction between the two embryologic origins of the rectum?
The pectineal line
What are the longitudinal folds in the anal mucosa above the pectineal line?
Columns of Morgagni
What are the anal columns connected by inferiorly?
Mucosal folds called the valves of Ball
Where do the anal glands open?
Directly behind the valves
What muscles pull the anal rectal junction anteriorly?
Puborectalis and levator ani
Which anal sphincter is made of smooth muscle?
Internal circular sphincter
The external anal sphincter has how many parts?
3, Deep, superficial, and submucosal
What supplies innervation to the external anal sphincter?
Inferior rectal branch of the pudendal nerve
Which portion of the anal canal is insensitive to pain?
The portion above the pectinel line
What supplies blood to the lower half of the anal canal?
The inferior rectal branch of the internal pudendal artery