GIT Flashcards
What are the features of intraperitoneal organs? Give a few examples of intraperitoneal organs.
- Enveloped by visceral peritoneum which covers the organ both anteriorly and posteriorly.
- suspended within abdominal cavity and connects with abdominal wall via mesentery
- mobile
- Stomach, liver, spleen
What are features of retroperitoneal organs? Give a few examples of retroperitoneal organs.
- Only covered in parietal peritoneum which only covers the organ’s anterior surface.
- fixed
- SAD PUCKER
- S: suprarenal (adrenal glands), A: aorta/IVC, D: duodenum (except the proximal 2cm, the duodenal cap), P; pancreas (except the tail), U: ureters, C: colon (ascending & descending parts), K: kidneys, E: esophagus, R: rectum
What is the difference between primary and secondary retroperitoneal organs?
- Primary: develop and remain outside the parietal peritoneum. (oesophagus, rectum, kidneys)
- Secondary: initially intraperitoneal, suspended by mesentery. Became retroperitoneal as their mesentery fused with posterior abdominal wall. (ascending and descending colon)
What is the function of the peritoneum?
- Covers nearly all viscera within the gut and conveys neurovascular structures from the body wall to intraperitoneal viscera.
Describe the structure of the mesentery and its function.
- Double layer of visceral peritoneum.
- Connects an intraperitoneal organ to the posterior abdominal wall.
- Provides a pathway for nerves, blood vessels and lymphatics to travel from body wall to the viscera.
Describe the structure of peritoneal ligaments and its function.
- Double fold of peritoneum that connects viscera together or connects viscera to abdominal wall.
- example is hepatogastric ligament (connects liver to stomach.
What does referred pain mean? What is its significance?
- Pain is referred according to the embryological origin of the organ so pain from foregut structures are referred to the epigastric region, midgut structures are to the umbilical region and hindgut structures to the pubic region of the abdomen.
Where can pain in retroperitoneal organs be referred to?
- back pain
Describe the pathway of referred pain in appendicitis.
- Initially, pain from the appendix (midgut structure) and its visceral peritoneum is referred to the umbilical region.
- As appendix becomes increasingly inflamed, it irritates the parietal peritoneum, causing pain to localise to the right lower quadrant.
What muscles make up the anterior abdominal wall?
- External oblique: superficial, inferomedial fibre direction
- Internal oblique: intermediate, superomedial fibre direction, arise from inguinal ligament
- Tranversus abdominus: innermost, transverse fibre direction, arise from inguinal ligament
- Rectus abdominis
- Pyramidalis muscles
What are the insertions of inferior part of external oblique muscle?
- Lateral part attaches to iliac crest and anterior superior iliac spine
- Central part is free, with no attachments
- Medial part attaches to the pubic tubercle and pubic crest
Where is the inguinal ligament?
- Free inferior border of external oblique muscle
- Thickened as a undercurving fibrous band (curved inwards to the body)
- Extends from anterior superior iliac spine (laterally) to pubic tubercle (medially)
Where are the attachments of the external oblique muscle?
attaches to ribs, linear alba, iliac crest
Where are the insertion and attachments of the internal oblique muscle?
- insert into pubic crest via conjoint tendon
- medially attach to linea alba, superiorly attach to costal margin, posteriorly attach posterior abdominal wall muscle
Where are the insertion and attachments of the transversus abdominus?
- insert into pubic crest via conjoint tendon
- medially attach to linea alba, superiorly attach to costal margin, posteriorly attach to posterior abdominal wall muscle
What are the vertically orientated muscles of anterior abdominal wall?
- Rectus abdominis: principle vertical muscles, intersected by tendons, enclosed by rectus sheath, right next to linea alba, arise inferiorly from the pubic bone and ascend and overlap costal margin attaching to rib cage
- Pyramidalis muscle
What is the function of tendinous intersection?
- Helps rectus abdominus become shorter but stronger
What forms the rectus sheath and what is it’s role?
- Formed by the sponeurosis of EO, IO and TA
- fibrous compartment for rectus abdominis
List the 8 layers of anterior abdominal wall from superficial to deep.
- skin, superficial fascia, external oblique, internal oblique, transversus abdominus, transversalis fascia, extraperitoneal fascia (fat), peritoneum
Describe the pathway of the development of testes.
- Initially developed at posterior abdominal wall in layer 7 (extraperitoneal fat)
- It begins to descend to anterior abdominal wall which is still in layer 7 and punctures a hole in transversalis fascia and goes inferomedially/obliquely.
- It descends beneath the arches fibre of the transversalis abdominus and arches fibre of internal oblique muscles
- It leaves the anterior abdominal wall through the fibrous split of external oblique muscle
- Then it descends obliquely down into scrotum via inguinal canals as spermatogenesis requires lower temperature
- As it descends, it takes each layer and its nerves, vessels and ducts forming the spermatic cord
Which layers of the anterior abdominal wall is not involved in inguinal canal?
- Doesn’t involve skin and superficial fascia layers
What are the features of the inguinal canal?
- Deep (internal) inguinal ring: a circular hole in the transversalis fascia
- Superficial (external) inguinal ring: a triangular split between those fibres of the external oblique aponeurosis
- Superior to the inguinal ligament
What are the boundaries of inguinal canal?
- Floor: inguinal ligament
- Roof: arching fibres of internal oblique and transversus abdominus
What is indirect inguinal hernia?
- occurs laterally to the inferior epigastric vessels
- bowel enters the inguinal canal via the deep inguinal ring
- more common
What is direct inguinal hernia?
- Occurs medially to the inferior epigastric vessels
- bowel herniates through a weakness in the inguinal triangle and enters the inguinal canal
- it can then exit the canal via the superficial inguinal ring and form a lump
- acquired due to weakening in abdominal musculature
Where are the attachments of posterior abdominal wall muscle?
- L1-5 and intervertebral discs 12th ribs
What are the muscles of posterior abdominal wall?
- Psoas major
- Quadratus lamborum
- Iliacus
Where does psoas major arise from and insert in?
- Arise from lumbar vertebrae
- Pass inferiorly beneath inguinal ligament
- insert to lesser trochanter of femur
Where does quadratus lumborum arise from and insert in?
- Arise from 12th ribs and tops of lumbar transverse process
- Lateral to psoas major
- Insert to iliac crest (superior part)
Where is the iliacus muscle?
- trangular shaped muscle beneath quadratus lumborum
- fills space of iliac fossa
What are the hollow viscera?
- Esophagus, stomach, small intestine, large intestine, gall bladder
What are the solid viscera?
- liver, pancreas, spleen
What is the difference between visceral and parietal peritoneum?
- Visceral covers abdominal viscera
- Parietal covers abdominal walls
What are the 3 constrictions along the esophagus?
- cervical: pharyngo-esophageal constriction/upper esophageal sphincter, due to cricoid cartilage at level C5/6, anatomical
- thoracic: aorta-bronchial constriction, due to aortic arch at level T4/5
- diaphragmatic: diaphragmatic constriction/lower esophageal sphincter, at esophageal hiatus at level T10/11, functional
Where does the esophagus start and end?
- Originates at inferior border of the cricoid cartilage (C6) and extends to the cardiac orifice of the stomach (T11)
Describe the pathway of the esophagus.
- Descends downwards from C6 into the superior mediastinum of the thorax, behind the trachea.
- Enters the abdomen via the esophageal hiatus (opening at right crus of the diaphragm) at T10.
- Enters right side of stomach terminating at cardiac orifice of stomach at T11.
What is the esophagus covered by?
- 2 layers of muscle (external longitudinal layer and internal circular layer)
What is the significance of the esophagogastric junction (Z line)?
- Clearly tells us where changing point of esophagus to stomach is
- There is s definitive sharp change in mucosa
Which quadrant is the stomach located in?
- left upper quadrant
Which quadrant is the small intestine located in?
- duodenum: mostly right upper quadrant
- jejunum: mostly left upper quadrant
- ileum: mostly right lower quadrant
What makes up the wall of the small intestine?
- 2 complete muscle layers (external longitudinal and internal circular)
List the parts of the large intestine.
- Caecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum
What is the largest solid viscus in our body?
- liver
Where is the liver located?
- Mainly in right upper quadrant
- tucked right underneath right dome of diaphragm
What makes up the portal triad?
- Portal vein, hepatic artery, bile duct
What are the 2 anatomical and functional lobes of the liver?
- Anterior/diaphragmatic surface: right lobe and left lobe, separated by falciform ligament, functionally independent
- Posterior/visceral surface: caudate lobe and quadrate lobe, separated by sagittal fissures and transverse portal hepatis
What is the function of the gallbladder?
- Stores and concentrates bile
How does bile become stored in the gall bladder?
- When sphincter at the major duodenal papilla is closed, the bile that is constantly produced by the liver travels back up and drains into the gall bladder.
How is our food broken down in the small intestine?
- When we eat, the bile duct muscles contract and hormones cause major duodenal papilla to relax and open.
- This causes the bile to be squeezed out and into the duodenum via common bile duct.
Which ducts form the common bile duct?
- common hepatic duct and cystic duct
Where is the pancreas located?
- left upper quadrant
- right up against posterior abdominal wall
Where is the pancreas tail located?
- tucked right against hilum of spleen.
What is the function of the main pancreatic duct?
- collects pancreatic enzyme from pancreas tail, body, neck, head and opens via major duodenal papilla
What is the function of the accessory pancreatic duct?
- collects small proportion of pancreatic enzymes from lower part of pancreas head and opens via minor duodenal papilla
Where is the spleen located?
- Left upper quadrant
Where is it most vulnerable for the spleen to get injured? What are the consequences?
- Ribs 9, 10, 11
- Profuse bleeding into peritoneal cavity, could bleed to death
- Need to quickly tie off the splenic artery and veins.
What is the blood supply for foregut, midgut and hindgut?
- foregut: celiac trunk
- midgut: superior mesenteric artery
- hindgut: inferior mesenteric artery
Where is the venous drainage of paired viscera and abdominal walls?
- Directly drains into the IVC
where is the venous drainage of unpaired viscera (except live)?
- Drains into IVC via the portal vein
