Introduction To The Abdomen Flashcards
What are the borders of the abdominal cavity width ways?
Diaphragm
Pelvic girdle
What are the 4 quadrants of the abdominal cavity? How are they split?
RUQ, LUQ, RLQ + LLQ split using the umbilicus + midsternal planes
What is contained within the right upper quadrant (RUQ)?
Ascending colon (hepatic flexure) Duodenum (1-3) Gall bladder Biliary tree IVC Pancreas (head + neck) Pylorus Right kidney Ureter Suprarenal gland
What is contained within the left upper quadrant (LUQ)?
Descending colon (splenic flexure) Duodenum (4) Left kidney Ureter Suprarenal gland Pancreas (body + tail) Spleen Stomach Jejunum Ileum
What is contained with the right lower quadrant (RLQ)?
Ascending colon Caecum Appendix IVC Right ductus deferens Ovary Uterine tube Ureter Ileum
What is contained within the left lower quadrant (LLQ)?
Descending colon Sigmoid Left ductus deferens Ovary Uterine tube Ureter Jejunum Ileum
What are the planes of the abdomen? What are their landmarks?
Transpyloric (L1)
Subcostal (L3)
Supracristal (L4)
Transtubercular (L5)
What are the 9 regions of the abdomen? How are they split?
R + L hypochondrium Epigastric R + L flank Umbilical R + L iliac fossa Pubic
Split down the MCLs, subcostal (L3) + transtubercular plane (L5)
What does the epigastric region of the stomach contain?
Stomach Liver Gallbladder Transverse colon Lesser sac Abdominal aorta Duodenum Pancreas Kidneys Suprarenal glands Origin/plexus of coeliac trunk + SMA
What can pain in the epigastric region indicate?
Foregut pain Aortic aneurysm Pancreatitis Ulcer Gastritis Reflux MI Pericarditis
What is contained within the umbilical region?
SI
Root of mesentery
Abdominal aorta
Origin/plexus of IMA
What can pain in the umbilical region indicate?
Midgut pain
Enteritis
Intestinal obstruction
Mesenteric occlusion
What is contained within the pubic region?
SI Sigmoid colon Upper rectum Ovary Uterine tube Distended bladder Enlarged uterus Common iliac arteries
What can pain in the pubic region indicate?
Hindgut pain Uterine pathology Urinary tract infection/obstruction Endometriosis PID
What is contained within the right and left hypochrondrium?
Diaphragm
Costodiaphragmatic recesses
R: Liver, hepatic flexure of colon
L: stomach, spleen, pancreatic tail + splenic flexure of colon
What can pain in the right and left hypochondrium indicate?
R: Liver abscess, hepatitis, gallbladder/biliary tree problem, cholecystitis, cholelithiasis
L: constipation, splenic infarct, abscess, colitis, diverticulitis, pyelonephritis
What is contained within the right and left flank?
Ascending (R)
Descending (L)
SI
What can pain in the right and left flank indicate?
Ascending colitis (R)
Descending colitis (L)
Nephrolithiasis
Pyelonephritis
What is contained within the right and left iliac fossa?
R: caecum, appendix
L: sigmoid colon
What can pain in the right and left iliac fossa indicate?
R: appendicitis, gonadal pathology, gastroenteritis, inguinal hernia
L: diverticulitis, colitis, gonadal pathology, inguinal hernia, UC
What is a hernia?
Protrusion of tissue/organ through a retaining tissue either inside or outside the body
What may predispose someone to develop a hernia?
Strain Recent operation Pregnancy Stomach muscle weakness (e.g. failure of abdominal wall to close properly in womb as a congenital defect) Advanced aging Chronic coughing
What are the muscular layers of the abdominal wall (in order from most external to internal)?
Rectus abdominis
External oblique
Internal oblique
Transversus abdominis
What are the functions of the rectus abdominis?
Flex vertebral column outwards
Allows stomach to protrude upwards when lying down
(muscle fibres run vertically so move in this direction)
What is the rectus sheath?
Fibrous sheath formed by the aponeuroses of flat abdominal wall muscles + the transversalis fascia that encloses the rectus abdominis muscle + epigastric vessels (inferior epigastric artery + vein)
What happens to the rectus abdominis during pregnancy?
Stretches + moves away from midline (may predispose women to hernias around the umbilicus)
What is the name of the midline fibrous aponeuroses?
Linea alba (runs from pubic bone up to sternum) that connects to all the abdominal muscular layers
What is the inguinal ligament?
The free lower border of the external oblique passing from the ASIS to the pubic tubercle
What direction to the muscle fibres go in the external oblique?
Diagonally downwards towards the midline where it connects to the rectus sheath
What is the linea alba made up of?
Anterior part of intermediate fascia + all the superficial fascia until the arcuate line where the rest of the rectus abdominis goes behind the deep fascia
What direction does the internal oblique muscle fibres go in?
Diagonally upwards towards the midline
What is attached to the internal oblique muscle?
Linea alba
Some of the lower ribs
Rectus sheath
What direction does the transversus abdominis muscle fibres run in?
Horizontally
Where is the neurovascular plane?
Between the transversus abdominis + the internal oblique
What are the functions of the abdominal wall muscles collectively?
Movement Support Pressure for defecation/urination Giving birth Vomiting Cough Holding everything in
In order from superficial to deep, what are the layers of the abdominal wall?
Skin Superficial fascia Muscle + aponeuroses Tranversalis (deep) fascia Parietal peritoneum
Why is it useful to know the structure of the linea alba during surgery?
It does not contain any vessels so will not heal well however, you can safely stick a needle or cannula into it
How does the upper 3/4 of the rectus sheath differ from the lower 1/4?
Above arcuate line (~umbilicus) there is aponeurotic fibrous tissue all around the rectus abdominis
Below the arcuate line, this fibrous tissue is only present anteriorly, posteriorly it is formed by the transversalis fascia
Where do the superior and inferior epigastric arteries travel? Why is this useful to know?
Travel + meet in rectus sheath
This unites the subclavian artery with the external iliac artery forming an arterial shunt if the aorta is narrowed
What are the surgical incisions that can be made in the abdomen to gain access?
Median/midline (linea alba incised)
Paramedian (rectus sheath incised)
Gridiron (muscle splitting) at McBurney’s point
Pfannenstiel (suprapubic)
Subcostal (Kocher) (inferior to costal thoracic margin)
What is at high risk of damage if making a subcostal (Kocher) incision?
T9 nerve
Superior epigastric artery
Thoracoabdominal nerves
In a paramedian incision, why is the rectus muscle displaced laterally?
To move the muscle fibres in a direction that will not damage all the nerves attached to it
Where does abdominal wall lymphatic fluid drainage pass to?
Axillary lymph nodes (RUQ + LUQ)
Inguinal lymph nodes (RLQ + LLQ)
Where is the gut tube located? What is it surrounded by?
Located within peritoneal cavity + surrounded by a layer of tissue called peritoneum
What is the difference between retro-peritoneal and secondary retro-peritoneal?
Retro-peritoneal: structure behind (outside) peritoneum
2ndary: intra-peritoneal structure that later becomes retroperitoneal
What is mesentery?
Double-layered fold of peritoneum suspending an organ from the abdominal wall
- supplies GI tract with blood supply + lymph drainage
What do we start off as in development?
A multi layered flat sheet of cells surrounded by fluid-filled bags
What needs to happen to the flat disc of cells during embryo development to form the gut tube?
Lateral folding so that a prawn-shaped tube is formed -> puts skin on outside (ectoderm) + gut tube lining on inside (endoderm)
1 layer -> 2 layers (bilaminar embryonic disc) -> 3 layers (trilaminar embryonic disc)
What is the difference between visceral and parietal peritoneum?
Visceral: covers organs + insensitive to burning/cutting so visceral pain is vague, diffuse + poorly defined/located
Parietal: covers inside of body wall + has somatic innervation so highly sensitive to many stimuli
What are the 3 main arteries that branch from the abdominal aorta and supply the gut tube? What vertebral level to they originate from?
- Coeliac trunk (T12)
- SMA (L1)
- IMA (L3)
What are the 3 different regions of the gut tube? What are the boundary points between them?
Lower oesophagus FOREGUT 1.5th of duodenum MIDGUT Proximal 2/3 of transverse colon HINDGUT Upper anal canal
What type of sensory stimuli is the viscera sensitive to?
Stretch
Hypoxia
Chemicals
Environmental changes
BUT NOT cutting or thermal stimuli
What is a dermatome?
An area of skin innervated by a single spinal nerve
Why does visceral pain get referred?
Visceral (organ) + somatic sensory (afferent) nerves enter the spinal cord together + travel in the same spinal tracts
The brain confuses the location + origin of signal as it assumes the pain is of dermatomal (skin) origin
What are somatic nerves?
Sensory nerves innervating the skin
What are afferent and efferent nerves?
Afferents: away from the organ/gland to the brain
Efferent: from the brain to the organ/gland
Where does sympathetic and visceral sensory nerves of the gut tube travel?
Alongside the blood supply
What nerves innervate the different regions of the gut tube?
Foregut: T5-9
Midgut: T10-11
Hindgut: T12-L1
