GIT Anatomy Flashcards
Retroperitoneal Structures
SAD PUCKER
Suprarenal Glands (adrenals)
Aorta and IVC
Duodenum ( 2 - 4 parts)
Pancreas (except Tail)
Ureters
Colon
Kidneys
Esophagus (lower 2/3)
Rectum
Principle; Injury = blood or gas in retroperitoneal space
Pain radiating backwards
Digestive Tract Layers
+ Application to ulcers and erosions
MSMS
Mucosa
- Epithelium (absorption)
- Lamina Propria (support)
- Muscularis Mucosa (motility)
Submucosa
- Submucosal nerve plexus
Muscularis Externa
- Myenteric nerve plexus
Serosa
- Serosa = intraperitoneal
- Adventitia = retroperitoneal
Ulcers = submucosa, inner or outer mucosa
Erosions = Mucosa only
Frequencies of basal electric rhythm
Stomach; 3 waves/ min
Duodenum; 12 waves
Ileum; 8-9 waves
Digestive Tract Histology
Oesophagus
- Nonkeratinized stratfied squamous
Stomach
- Gastric Glands
Duodenum
- Villi and microvilli
- Brunners glands (submucusa) and crypts of liberkuhn
Jejunum
- Pilcae circularis and crypts
Ileum
- Peyer patches (lamina propria/ submucosa)
- Large numbers of goblet cells
Colon
- No villi,
- Crypts and goblet cells
Branches of the Abdominal Aorta
P C S R T L I S
Arteries supplying the GI structures exit anterioirly
Arteries supplying paired structures exit laterally
SMA syndrome occurs when the transverse portion of the duodenum is entrapped between the SMA and aorta causing intestinal obstruction.
Phrenic
Coeliac (T12)
Superior Mesenteric (L1)
Renal
Testicular
Lumbars
Inferioir Mesenteric (L3)
Sacral
GI Blood Supply and Innervation
Branches of Celiac Trunk
Main Branches; Common Hepatic, Splenic, Left Gastric
Short gastrics have poor anastomosis if splenic artery is blocked
Strong anastomoses exist between
- L/ R gastroepiploics
- L/ R gastrics
Collateral Arterial Circulation
If branches of the Abdominal Aorta are blocked these arterial anastomoses compensate;
Superioir epigastric (internal thoracic) ⇔ inferioir epigastric (external iliac)
Superioir pancreaticduodenal (celiac trrunk) ⇔ inferioir pancreaticduodenal (SMA)
Liddle colic (SMA) ⇔Left Colic (IMA
Superioir Rectal (IMA) ⇔ middle and inferior rectal (Internal Iliac)
Portosystemic Anastomoses
Pectinate Line
Above Pectiante Line;
Internal Haemorrhoids
Adenocarcinoma
Arterial supply from the superior Rectal (branch of IMA)
Venous drainage is to superioir rectal veins -> internal pudendal -> internal iliac vein -> IVC
Below Pectinate Line;
External Hemorrhoids
Anal Fissues
Arterial supply; inferiori rectal (branch of internal pudendal)
Venous; inferior rectal -> internal pudendal -> internal iliac -> IVC
Anal Fissure
Tear in the anal mucosa
Below Pectinate Line
Pain while Pooping
Blood on Paper
Located posterioirly as this area is poorly perfused
Internal vs External Hemorrhoids
Internal;
- Above pectinate line
- Visceral innervation = not painful
- Lymphatic drainage to deep nodes
External;
- Below pectinate line
- Somatic innervation = painful
- Lymph drainage to superficial inguinal nodes
Liver Anatomy
Apical surface of hepatocytes = canalicculi
Basolateral surface = faces sinusoids
Acinar Model of Liver Physiology (Zones)
Zone 1; Periportal zone
- Affected 1st by viral hepatitis
- Ingested Toxins (cocaine)
Zone 2; Intermediate zone
Zone 3; Pericentral Vein zone
- Affected 1st by ischaemia
- Contains p450
- Sensitive to metabolic toxins
- SIte of alcoholic hepatitis
Billiary Structures
Gallstones that reach the common channel at the ampulla of vater can block both the bile and pancreatic ducts
Tumors that arse in the head of pancreases (near duodenum) can cause obstruction of the common bile duct
Femoral Region (Organisation = NAVEL)
Lateral to medial;
- N: Nerve.
- A: Artery.
- V: Vein.
- E: Empty space (this is important as it allows the veins and lymph vessels to distend, so they can cope with different levels of flow).
- L: Lymph canal
As this area is a triangle, it has three borders:
Superior border – Formed by the inguinal ligament, a ligament that runs from the anterior superior iliac spine to the pubis tubercle.
Lateral border – Formed by the medial border of the sartorius muscle.
Medial border – Formed by the medial border of the adductor longus muscle. The rest of this muscle forms part of the floor of the triangle.
Femoral Triangle Contents
Femoral Sheath Contents
The femoral triangle contains some of the major neurovascular structures of the lower limb. Its contents (lateral to medial) are:
Femoral nerve – Innervates the anterior compartment of the thigh, and provides sensory branches for the leg and foot.
Femoral artery – Responsible for the majority of the arterial supply to the lower limb.
Femoral vein – The great saphenous vein drains into the femoral vein within the triangle.
Femoral canal – A structure which contains deep lymph nodes and vessels.
The femoral artery, vein and canal are contained within a fascial compartment – known as the femoral sheath.
Inguinal Canal - Overview
The inguinal canal is a short passage that extends inferiorly and medially, through the inferior part of the abdominal wall. It is superior and parallel to the inguinal ligament.
It acts as a pathway by which structures can pass from the abdominal wall to theexternal genitalia.
The inguinal canal also has clinical importance. It is a potential weakness in the abdominal wall, and therefore a common site of herniation.
Inguinal Canal - Boundaries
The inguinal canal is made up of:
Anterior and posterior walls
Superficial and deep rings (openings)
Roof and floor (or superior and inferior walls)
We shall go through each component in turn.
The anterior wall is formed by the aponeurosis of the external oblique, and reinforced by the internal oblique muscle laterally.
The posterior wall is formed by the transversalis fascia.
The roof is formed by the transversalis fascia, internal oblique and transversus abdominis.
The floor is formed by the inguinal ligament (a ‘rolled up’ portion of the external oblique aponeurosis) and thickened medially by the lacunar ligament.
Types of Hernias
Diaphragmattic Hernia
Indirect Inguinal Hernia
Direct Inguinal Hernia
Femoral Hernia
