GI: Anatomy Flashcards
What are the layers of the abdominal wall?
- Skin
- Fascia/Fat (superficial and deep)
- 3X anterolateral muscles
- Peritoneum
Which muscle is enveloped by the aponeurosis of the lateral muscles?
Rectus abdominus
Forms the rectus sheath
What are the 3 anterolateral muscles?
- External oblique
- Internal oblique, transverse abdominis, Rectus abdominis)
- Transversalis fascia
What is the arcuate line?
- Lower limit of the posterior layer of rectus sheath
- Point at which inferior epigastric vessels pierce rectus abdominus
- Roughly half way between umbilicus and pubic crest
What is mesentery?
Double fold of peritoneum that attaches the viscera to the posterior abdominal wall
Contains blood vessels, lymph vessels, nerves and fat
What are the organs that are connected by mesentery?
- Jejenum
- Ileum
- Appendix
- Transverse Colon
- Sigmoid Colon
- Rectum
What is the peritoneal ligament?
- Gastrocolic ligament (Stomach to transverse colon)
- Gastrosplenic ligament (Stomach to spleen)
- Falciform ligament (liver ot anterior abdominal wall)
- Triangular ligaments (liver to diaphragm)
What are the omenta?
- Double folds of peritoneum
- Greater omentum hangs off the greater curve of the stomach and folds back up and attaches to the anterior surface of the transverse colon
- Lesser omentum connects lesser curve of the stomach to the liver
What is the blood supply to the GI tract?
Arterial is from branches of the aorta
- Coeliac trunk
- Superior mesenteric artery
- Inferior mesenteric
Venous drainage goes to the liver via the Hepatic Portal Vein
-Portal system
What is the composition of saliva?
- Mostly water (Hypotonic)
- Rich in potassium and bicarbonate
- Mucins to help with lubrication
- Enzymes: Amylase, Lingual lipase
- Diversity of immune proteins
What are functions of saliva?
- Creation of bolus
- Initaite process of digestion
- Oral hygiene
- Transmitting disease
- Protection of mouth
- Speech
- Solvent for taste
What are the 3 pairs of salivary glands?
- Parotid gland
- Sub lingual gland
- Sub mandibular gland
Outline the anatomical relationships of the oesophagus
- Originates in the neck at 6th cervical vertebrae
- Sits posteriorly the larynx and trachea
- Closely related to the aorta (right hand side)
- Pierces the diaphragm at T10 (oesophageal hiatus)
What are the nervous supply for the submandibular and sublingual?
-Parasympathetic from the facial nerve
What is the nervous supply for the parotid gland?
- Parasympathetic fibres from the glossopharyngeal fibres
- Increases production of saliva
What are the narrowings found in the oesophagus?
- Tightest narrowing is the junction between the pharynx and oesophagus
- Second narrowing is when the arch of aorta crosses the oesophagus
- Third narrowing is when the left main bronchus crosses the oesophagus
- Final narrowing is when oesophagus passes through diaphragm (T10)
Describe the protective mechanisms of the nasal cavity and the larynx during swallowing.
- The nasal cavity is protected by elevation of the soft palate
- The respiratory tract is protected by elevation of the larynx (which closes epiglottis) and adduction of the vocal cords.
What are the contents of the external muscle layers?
- Inner circular muscle
- Outer longitudinal muscle
What are the ligament of the liver and their attachments?
Falciform ligament
-Attaches the anterior surface of the liver to the anterior abdominal wall. Free edge contains the ligamentum teres
Coronary ligament
-Attaches the superior surface of the liver to the diaphragm
Right and Left Triangular ligament
-Attaches the superior surface of the liver to the diaphragm
Inferior vena cava – Secures to the posterior surface of the liver through hepatic veins and fibrous tissue
Lesser omentum
What are the parts of the lesser omentum?
Hepatic duodenal ligament which extends form the duodenum to the liver
Hepatogastric ligament which extends from the stomach to the liver
What are the macroscopic features of the liver?
4 lobes
- Divided into right and left lobes by the falciform ligament
- Caudate lobe on the upper aspect of the visceral surface. Lies between inferior vena cava and a fossa produced by the Ligamentum Venosum
- Quadrate lobe located on the lower aspect of the visceral surface. Lies between gallbladder and a fossa produced by the Ligamentum Teres
What are the main branches of the coeliac trunk and their path?
- Left gastric which travels along the lesser curve of the stomach where it anastomose with the right gastric artery
- Splenic artery which travels towards the spleen running posteriorly to the stomach and along the superior margin of the pancreas. Terminates to supply the spleen
- Common hepatic arteries which travels past the superior aspect of the duodenum
What are the branches of the splenic artery and area of supply ?
- Pancreatic branches which supply the body and tails of the pancreas
- Left gastroepiploic which supplies the greater curvature of the stomach
- Short gastric which supplies the fundus of the stomach
What are the branches of the common hepatic artery and path?
- Proper hepatic artery ascends through lesser omentum
- Gastroduodenal artery descends posterior o the superior portion of the duodenum
What are the branches of the gastroduodenal artery and area of supply?
- Right gastroepiploic which supplies the greater curvature and greater omentum
- Superior pancreatoduodenal artery which supplies the head of the pancreas
What are the branches of the proper hepatic artery and their area of supply?
- Right gastric to supply the pylorus and lesser curvature of the stomach
- Right and left hepatic artery which divide inferior to porta hepatis to supply the respective lobes of the liver
- Cystic which is a branch of the right hepatic which supplies the gallbladder
What are the regions of the peritoneal cavity?
- Greater sac (larger portion)
- Lesser sac
What are the areas of the greater peritoneal sac separated by?
Transverse colon
- Supracolic
- Infracolic
How are the colics connected by?
Paracolic gutters
Where does the lesser peritoneal sac lie?
- Lies posterior to the stomach
- Known as omental bursa
- Allows stomach to move freely against the structures inferior and posterior to it
What connect the greater and lesser sac?
-Epiploic foramen which lies posterior to the ligamentum teres
Where does the rectovesical pouch lie?
Double folding of peritoneum between the rectum and the bladder. The peritoneal cavity is completely closed in males.
Where does the pouch of Douglas lie?
Rectouterine Pouch
Double folded extension of the peritoneum between the rectum and the posterior wall of the uterus.
Where does the vesicouterine pouch lie?
The vesicouterine pouch is a double fold of peritoneum between the anterior surface of the uterus and the bladder.
What are the primarily retroperitoneal organs?
- Oesophagus
- Rectum
- Kidneys
What are the secondarily retroperitoneal organs?
- Ascending colon
- Descending colon
Describe the surface anatomy of foregut organs on the abdominal wall.
Stomach - Epigastrium
Duodenum - Epigastrium
Liver – Lies in the dome of the right diaphragm. Right hypochondrium and epigastric region
Pancreas – Lies in C shape of duodenum. Behind the stomach. Tail in left Hypochodnrium
Spleen – Lies near 10th rib and posterior
Describe the surface anatomy of the midgut organs on the abdominal wall.
Jejunum - Left lumbar and umbilical regions of abdomen
Ileum – terminate in right inguinal region and mainly lower portion of abdomen
Caecum – Appendix arise here. Right inguinal region
Ascending Colon – Arise from right inguinal region to right lumber region
Describe the surface anatomy of the hindgut organs on the abdominal wall.
Transverse colon – Arise from the ascending colon and travels transversely across abdomen
Descending colon – Left lumber region to Left inguinal
Sigmoid colon – Arises from left inguinal
Rectum
What is formed by the aponeuroses of all the flat muscle in the midline?
Linea alba
Which muscle is located in the middle of the abdominal wall?
- Rectus abdominus
- Split into 2 by the linea alba
- Lateral border is the linea semilunares
- Tendinous intersections form the six pack
What forms the anterior wall of the rectus sheath?
-Aponeuroses of the external oblique and half of the internal oblique
What forms the posterior wall of the rectus sheath?
-Aponeuroses of half the internal oblique and transverse abdoniums
At Arcuate line the apoenurses all become anterior
What is the path of the superior mesenteric artery?
- Arises at L1 anteriorly to the abdominal aorta
- Descends down the posterior aspect of the abdomen.
- Supplies the midgut
What are the anatomical relations with the superior mesenteric artery?
Anterior to the SMA
- Pyloric part of the stomach Splenic vein
- Neck of the pancreas
Posterior to the SMA
- Left renal vein
- Uncinate process of the pancreas – hooks around the back of the SMA
- Inferior part of the duodenum
What are the major branches of SMA?
Inferior Pancreaticoduodenal – Inferior region of the dad of the pancreas, uncinate process, duodenum
Right colic – Supplies the ascending colon
Illeocolic artery – Ascending colon, Appendix, Caecum, Ileum
Middle colic artery – Supplies the transverse colon
Jejununal arteries – Supplies the jejunum. Smaller number of arterial arcades but longer vasa recta than illegal arteries
Ileal arteries – Supplies the ileum
What is unique about the superior mesenteric artery blood supply?
Formation of arcade to supply the parts of the GUT
What is the path of the inferior mesenteric artery?
Arise at L3 near the inferior border of the duodenum
Depends anteriorly then moves to the left side and it is a retroperitoneal
Supplies the hindgut
What are the major branches of the inferior mesenteric artery?
Left colic artery
- Ascending branch which supplies the distal 1/3 of the transverse colon, and the upper aspect of the descending colon.
- Descending branch – moves inferiorly to supply the lower part of the descending colon. It anastamoses with the superior sigmoid artery.
Sigmoid arteries - supply descending colon and the sigmoid colon
Superior Rectal artery - supplies the rectum
What is the marginal artery?
Continuous arterial circle along the inner border of the colon. Straight vessels arise form the artery to supply the colon.
What makes up the marginal artery?
- Illeocolic, right colic and middle colic of superior mesenteric artery.
- Left colic and sigmoid branches of the inferior mesenteric artery
What is the arc of riolan?
Anastomosis between the middle colic branch of superior mesenteric artery and left colic branch of inferior mesenteric artery.
Which artery can a horseshoe kidney hook onto?
Inferior mesenteric artery
What is the venous drainage of the gut?
Hepatic portal vein
