Module 13 : GI Tract Flashcards
esophagus
- muscular tub e
- passes through hiatus of the diaphragm at T 10
- anterior to aorta
- enters superomedial aspect of the stomach (cardia)
- GE junction marks juncture of the greater and lesser curvatures of the stomach
stomach
- left hypochondirum
- epigastric regions
- peritoneal
- lower aspect crosses midline and terminates at the duodenum
- 6 parts
+ cardia
+ fundus
+ body
+ greater curve
+ ;esser curve
+ pylorus
cardia
- surrounds lower esophageal sphincter
fundus
- rounded portion
- superior and left of cardia
body
- large central portion
lesser curve
- concave medial portion
greater curve
- convos lateral portion
pylorus
- pyloric canal, pyloric antrum
- disstal aspect of stomach
- on an empty stomach lies on right of midline
- fully distended shifts 5-8cm to the right off midline
small bowel
- 3 parts
+ duodenum
+ jejunum
+ ileum
duodenum
- shortest widest and most fixed
- 4 parts
+ first part
+ second part
+ third part
+ fourth part
first part of duodenum
- superior/ bulb
- intraperitoneal
- from pylorus running upward and backward to level of GB neck
second part od duodenum
- descending
- retroperitoneal
- CBD and main pancreatic duct insertion
third part of duodenum
- transverse/horisontal
- retroperitoneal
fourth part of duodenum
- ascending
- runs superior and to the peft
- retroperitoneal
jejunum
- intraperitoneal at ligament of treitz (connects bowel to diaphragm)
- arranged in multiple loops
- occupies the umbilical and left iliac regions
ileum
- longest portion
- umbilical hypogastric right iliac and pelvic regions
- joins large bowel at ileocecal sphincter
- ileum and jejunum anchored to posterior abdominal wall by mesentery
large bowel / colon
- multiple division
- cecum ascending transverse descending sigmoid rectum and anal canal
cecum
- pouch like portion at origin of ascending colon
- right lower quadrant
- appendix extends from inferior portion
- retroperitoneal
appendix
- blind ended tubular structure
- opens into cecum
ascending colon
- retro peritoneal
- superior path along right flank
- from right iliac fossa to visceral surface of right lobe
- hepatic flexure
+ connect ascending and transverse colon
+ 90 degree curve shadows kidney
transverse colon
- intraperitoneal
- travels horizontally across mid abdomen anterior to duodenum
- splenic flexure
+ bends downward 90 degrees inferior to spleen connecting transverse to descending colon
descending colon
- retroperitoneal
- descends on left side of abdomen to left iliac fossa
- extends over pelvic brim
sigmoid colon
- terminal end of colon
- projects inward toward midline e
- sits anterior to sacrum
rectum
- descends into true pelvis
- ends at anal canal
anal canal
- rectum penetrates levator ani mussen to become anal canal
GI anatomy
- continuous tube with 4 concentric layers \+ mucosa \+ submucosa \+ muscularis \+ serosa
mucosa
- epithelial lining loose connective tissue
- muscular mucosa
- innermost layer
- protects absorbs secretes
- hypo echoic
submucosa
- connective tissue blood vessels lymphatic
- nourishes surrounding tissue and transports absorbed nutrients
- hyper echoic
muscularis
- smooth muscle in circular and longitudinal
- responsible for movement of tube and its contents
- hyopechoic
serosa
- outer layer
- protection
- hyperechoic
stomach - anatomy
- characteristic folds called rugae
+ increase expansion and surface area - parallel to long axis of stomach
- disappear in distended state
small bowel anatomy
- folds called valvulae conniventes
- do not disappear when intestine is distended
- 3-5mm apart
- most prominent in duodenum and first half jejunum
large bowel anatomy
- huastral markings
+ 3-5 cm apart
gut signature
- district layered appearance of gut on ultrasound do to different acoustic properties of histological layers of GI tract
sonographic appearance
- uniform and compressible
- average thickness
+ 3mm (distended)
+ 5 mm (non distended) - assess bowel for motor activity
- keyboard sign = valvulae conniventes
- austral marking = ascending and descending colon
physiology
- primary function = digestion and absorption
- largest endocrine organ
- ingestion of flood stimulates release of hormones from endocrine cells in mucosa
GI hormones
- gastrin
- cholecystokinin
- secretin
gastrin
- released by stomach
- stimulates secretion of gastric acid
cholecystokinin
- CCK
- released by duodenum controls GB contraction
secretin
- released by duodenum to stimulate release of bicarbonate from panc to neutralize stomach acid
ultrasound land mark - ge junction
- anterior and left of aorta
ultrasound landmark - stomach
- antrum is anterior to panc
ultrasound landmark - duodenum
- lateral to panc head
ultrasound landmark - jejunum
- inferior to body and talk of pan
- anterior to left kidney
ultrasound landmark - cecum
- medial to ASIS and iliopsoas
ultrasound landmark - appendix
- posterior to cecum
ultrasound landmark - ascending colon
- anterior lateral to low pole of right kidney
ultrasound landmark - transverse colon
- inferior to pan and stomach
ultrasound landmark - descending colon
- adjacent to left flank over lw pole left kidney
ultrasound land mark - sigmoid
- anterior to external iliac
- poster to uterues
- posterior to bladder
vasculature
- celiac superior and inferior mesenteric arteries supply small and large bowel
- venous return from small and large bowel into portal system
- gastric artery and vein supply and drain stomach
ultrasound assesemnt
- asses diameter content and motor activity
wall thickness
- normal \+ 3 mm distendne \+ 5 mm undistended - if thickened \+ symmetric = inflammation \+ asymmetric = malignancy
content of lumen
- excessive amounts of fluid
+ hyper secretion
+ mechanical obstruction
+ paralytic ileus
activity
- increases with \+ mechanical bowel obstruction \+ or inflammation - decreases with \+ paralytic ileum \+ end stage mechanical obstruction
ultrasound prep and technique
- no prep fasting drinking water
- high frequency linear
- slow graded compression
- normal gut should compress and gas displaced
- use caution where tender