Anatomy Flashcards
Retroperitoneal structures include GI structures that lack mesentery and non-GI structures.
Injuries to retroperitoneal structures –> blood gas accumulation in retroperitoneal space
Suprarenal (adrenal) glands
Aorta + IVC
Duodenum (2nd through 4th parts)
Pancreas (except tail)
Ureters
Colon (descending and ascending)
Kidneys
Esophagus (thoracic portion)
Rectum (partially)

Important gastrointestinal ligaments (6)
- Falciform
- Hepatoduodenal
- Gastrohepatic
- Gastrocolic
- Gastrosplenic
- Splenorenal

Falciform ligament
- Connects: liver to anterior abdominal wall
- Structures contained:
- Ligamentum teres hepatis (derivative of fetal umbilical vein)
- Notes:
- Derivative of ventral mesentery
Hepatoduodenal ligament
- Connects: liver to duodenum
- Structures contained:
- Portal triad - proper hepatic a., portal vein, common bile duct
- Notes:
- Pringle maneuver - ligament may be compressed between thumb and index finger (placed in omental foramen to control bleeding)
- Borders omental foramen (foramen of Winslow), which connects greater and lesser sacs

Gastrohepatic ligament
- Connects liver to lesser curvature of stomach
- Structures contained:
- Gastric arteries
- Notes:
- Separates greater and lesser sacs on the right
- May be cut during surgery to access lesser sac

Gastrocolic ligament
- Connects greater curvature and transverse colon
- Structures contained:
- Gastroepiploic arteries
- Notes:
- Part of greater omentum

Gastrosplenic ligament
- Connects: Greater curvature and spleen
- Contains:
- Short gastrics, left gastroepiploic vessels
- Notes:
- Separates greater and lesser sacs on the left
- Part of greater omentum

Splenorenal ligament
- Connects: Spleen to posterior abdominal wall
- Structures contained:
- Splenic artery and vein, tail of pancreas

Digestive Tract Anatomy
Layers of the gut (inside to outside - MSMS)
- Mucosa - epithelium, lamina propria, muscularis mucosa
- Submucosa - includes submucosal nerve plexus (Meissner), secretes fluid
- Muscularis externa - includes myenteric nerve plexus (Auerbach), motility (inner circular layer, outer longitudinal layer)
-
Serosa (when intraperitoneal), adventitia (when retroperitoneal)
- Vasculature
- Lymphatics
Ulcers can extend into submucosa, inner or outer muscular layer.
Erosions = mucosa only

Frequencies of basal electric rhythm (slow waves)
- Stomach - 3 waves/min
- Duodenum - 12 waves/min
- Ileum - 8-9 waves/min
Digestive Tract Histology
Esophagus
Stomach
- Esophagus:
- nonkeratinized stratified squamous epithelium
- Stomach:
- gastric glands
Digestive Tract Histology
Duodenum
Jejunum
Ileum
Colon
Duodenum:
- villi and microvilli increase absorptive surface
- brunner glands (HCO3- secreting cells of submucosa)
- crypts of Lieberkuhn
Jejunum
- plicae circulares
- crypts of lieberkuhn
Ileum
- Peyer patches (lymphoid aggregates in lamina propria, submucosa)
- Plicae circulares (proximal ileum)
- crypts of lieberkuhn
- Largest number of goblet cells in small intestine
Colon
- crypts of lieberkuhn but NO VILLI
- Abundant goblet cells
Abdominal aorta and branches
T12
L1
L2
L3
L4
L5

Arteries supplying GI structures branch anteriorly.
Arteries supplying non-GI structures branch laterally and posteriorly.
- T12: IVC (Right), Celiac trunk, Middle Suprarenal
- L1-L2: SMA, Renal, Gonadal (testicular/ovarian)
- L3: IMA
- L4: “BiFOURcation”
- L5: R & L common iliac (w/ R & L internal iliac coming off), median sacral artery

SMA (Wilkie’s) Syndrome
Intermittent intestinal obstruction symptoms (primarily postprandial pain) when transverse (third) portion of duodenum is compressed between SMA and aorta
Typically occurs in conditions associated with diminished mesenteric fat (e.g., low body weight/malnutrition)
GI Blood Supply and Innervation:
Foregut
Artery: Celiac trunk (L gastric, common hepatic, splenic)
PSNS: Vagus
SNS: T5-T11
Vertebral level: T12-L1
Structures supplied:
- Pharynx (vagus nerve only), lower esophagus (celiac artery only) to proximal duodenum
- Liver, gallbladder, pancreas, spleen (mesoderm)
GI Blood Supply and Innervation:
Midgut
Artery: SMA
PSNS: Vagus
SNS: T11-T12
Vertebral level: L1
Structures supplied:
- Distal duodenum to proximal 2/3 transverse colon
GI Blood Supply and Innervation:
Hindgut
Artery: IMA
PSNS: S2-S4
SNS: L1-L2
Vertebral level: L3
Structures supplied:
- Distal 1/3 transverse colon to upper portion of rectum
Celiac Trunk = main blood supply of stomach
Strong anastomoses exist between:
Common hepatic artery, L gastric a., splenic artery
Anastomoses:
L and R gastroepiploics
L and R gastrics

Portosystemic anastomoses (3)
Site of anastamosis:
Clinical Sign:
Portal <–> Systemic:
- Esophagus
- Esophageal varices
- Left gastric <–> azygos
- Umbilicus
- Caput medusae
- Paraumbilical <–> small epigastric veins of anterior abdominal wall
- Rectum
- Anorectal varices
- Superior rectal <–> middle and inferior rectal

Treatment for portal HTN
TIPS (transjugular intrahepatic portosystemic shunt) b/w portal vein and hepatic vein relieves portal HTN by shunting blood to systemic circulation, bypassing liver
Pectinate (dentate) line
Formed where endoderm (hindgut) meets ectoderm
Above pectinate line issues
Blood supply
Lymphatic drainage
Internal hemorrhoids, adenocarcinoma
**Internal hemorrhoids receive visceral innervation –> not painful
Arterial supply: superior rectal artery (branch of IMA)
Venous drainage: superior rectal vein –> inferior mesenteric vein –> portal system
Lymphatic drainage to internal iliac lymph nodes

Below pectinate line issues
Blood supply
Lymphatic drainage
External hemorrhoids, anal fissures, SCC
**External hemorrhoids receive somatic innervation (inferior rectal branch of pudendal n.) –> PAINFUL if thrombosed
Arterial supply: inferior rectal artery (branch of internal pudendal a.)
Venous drainage: inferior rectal vein –> internal pudendal vein –> internal iliac vein –> common iliac vein –> IVC
Lymphatic drainage to superficial inguinal nodes

Anal Fissure
Description:
Association:
Tear in anal mucosa below pectinate line
- Pain while pooping
- Blood on toilet Paper
- Located Posteriorly b/c area is Poorly Perfused
Associated with low-fiber diets and constipation












