5) Surgical Anatomy of Abdomen Flashcards
What are the superior and inferior boundaries of the anterior abdominal wall?
Superiorly - cartilage of ribs 7-10 and xiphoid process
Inferiorly - iliac and pubic crests
What muscles make up the anterior abdominal wall?
External oblique, internal oblique, transversus abdominis and rectus abdominis
What is the function of the 3 flat muscles?
Act to flex, laterally flex and rotate the trunk. Their fibres run in differing directions - strengthening the abdominal wall and decreasing the risk of herniation.
What is the most superficial flat muscle and in which direction do its fibres run?
External oblique, inferomedial fibres
What is the middle flat muscle and in which direction do its fibres run?
Internal oblique, superomedial fibres
What is the deepest flat muscle and in which direction do its fibres run?
Transversus abdominis, horizontal fibres
What does the linea alba form from and where does it run?
Fusion of aponeuroses of all flat muscles in midline
Runs from xiphoid process to pubic symphysis
Describe the rectus abdominis:
Has tendinous intersections to make muscle more efficient
Lines semilunaris mark lateral border of muscle
What is the rectus sheath formed from?
Formed by the aponeuroses of the three flat muscles and encloses the rectus abdominus
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 of transversus abdominus
What is posterior to the rectus sheath and muscles?
Transversalis fascia, peritoneum and greater ommentum
What feature of the greater ommentum helps deal with infection?
Fat of GO can move to wall off an infection and create a local abscess
Where is the arcuate line and what is its significance?
About 1/2way between umbilicus and pubic crest
Where rectus sheath doesn’t surround rectus abdominis posteriorly, so is in direct contact with fascia
What is divarication of recti?
When linea alba is lax so when rectus abdominis contracts, muscle spreads apart
Who is divarication of recti more common in?
Women, who have had many children
What is a rectus sheath haematoma and who is at risk?
Bleeding into rectus abdominis which is a confined area, pain bad when using muscle.
Patients on warfarin at risk
What is Cullen’s sign and list some causes?
Peri-umbilical bleeding
Acute pancreatitis, aortic rupture, trauma, ruptured ectopic pregnancy
What can occur if a repaired surgical incision is weak?
Incisional hernia
Where is a midline incision made?
Straight down linea alba
Where is a transverse incision made?
Horizontal incision with external oblique aponeurosis being sutured
Operations of colon, duodenum and pancreas
Where is an appendicectomy incision made?
McBurney’s point - 2/3rds of the distance between umbilicus and ASIS.
What surgical technique is used in an appendicectomy?
Gridiron muscle splitting - spreading each muscle in direction it’s fibres run in, to minimise damage
What is ectopia cordis?
Heart located partially or totally outside of the thorax, so it’s right below the skin
What is a patent urachus?
Urachus remains, which connects bladder to umbilicus. Can present at birth or later in life when men develop bladder outflow obstruction due to BPH
What is a patent vitelline duct and what 3 conditions can it lead to?
Originally connects midgut to yolk sac
If remains can lead to Meckel’s diverticulum, vitelline cyst or fistula
What is Meckel’s diverticulum?
Cul de sac in ileum containing ectopic gastric or pancreatic tissue, which secretes acid and enzymes causing ulceration
What is a vitelline fistula?
Connection between umbilical and intestinal tract - faeces out of umbilicus
What is omphalocoele?
Persistence of physiological herniation where gut tube fails to return to abdominal cavity following normal herniation into umbilical cord
How could you tell the difference between omphalocoele and gastroschisis?
Physical appearance - omphalocoele will be covered in peritoneum and amnion, whereas gastroschisis will have no covering
What is gastroschisis?
Failure of closure of abdominal wall during folding, leaving gut tube out of the body
Where is the loin?
Middle back
Describe visceral pain:
Vague, diffuse and poorly localised
Why is visceral pain vague?
Visceral structures are highly sensitive to distension (stretch), ischemia and inflammation, but relatively insensitive to other stimuli. Pain related to embryological developmental region
Why is visceral pain poorly localised?
Low density of sensory innervation of viscera
What causes referred pain?
Referred pain is due to visceral afferent (sensory) nerve fibers entering the spinal cord at the same level sympathetic fibres and the pain is perceived as coming from somatic structures supplied by those spinal cord segments
What is somatic pain?
Dull or aching pain that is well localised
What is somatic referred pain?
Pain caused by stimulus in proximal part of nerve is perceived in distal dermatome of that nerve
Where is foregut pain perceived?
Epigastric region
Where is midgut pain perceived?
Periumbilical region
Where is hindgut pain perceived?
Suprapubic region
