GI Session 3 Flashcards
What is the purpose of the tendinous intersections which divide the rectus abdominis?
Damage less devastating
What is the linea alba?
Aponeurotic fibres from the three abdominal muscles where they meet near the midline
What are the layers of the abdominal muscle wall from superficial to deep?
External oblique
Internal oblique
Transversalis abdominis
What forms the anterior and posterior walls of the rectus sheath?
Anterior: external abdominal oblique +1/2 internal
Posterior: 1/2 internal and transversalis abdominis
What is the purpose of the rectus abdominis?
Contain it to prevent it from bowing
What are the layers of the abdominal wall fascia from superficial to deep?
Rectus sheath
Transversalis fascia
Peritoneum
Greater omentum
What is the function of the greater omentum?
Mobile fat which is can be used to isolate an area of infection e.g. in appendicitis
What is the arcuate line?
Line at umbilicus above which the posterior rectus sheath is present and below which only the anterior rectus sheath is present
Where is the arcuate line found in relation to the umbilicus?
1/3 of the distance between the umbilicus and pubic symphysis
What is a Pfannstiel incision?
1/3 of the distance between umbilicus and pubic symphysis above pubic symphysis where an incision for caesarean is made which will be hidden by pubic hair
What is divarication of recti?
Apparent hernia seen in midline actually due to laxity of linea alba after it has been stretched and become thin
What can cause divarication recti?
Obesity
Ageing
Post-surgery
Post-partum
What is rectus sheath heamatoma?
Blood accumulates in anterior rectus sheath which travels down to arcuate line and up anterior surface –> large visible bruise on abdominal surface darkest at arcuate line
How is rectus sheath heamatoma identified?
Pt lies flat and if legs/head raised this is very painful
Why do incisions for surgery have to be in aponeurosis fibres?
Sutures ‘cut out’ so don’t hold
Where are the surgical bites in midline and transverse incisions?
Midline: linea alba
Transverse: external oblique aponeurosis
Where is appendicectomy carried out?
McBurney’s point located 2/3 from the umbilicus to the R ASIS
What muscle-splitting incision must be used to cut through the abdominal muscles in appendicectomy?
Grid iron
What is ectopia cordis?
Uncommon congenital condition where the heart develops on the abdominal wall and is at high risk of fibrillation due to knocks
What happens in patent urachus?
Allantois duct fails to close and recede –> urine exiting via umbilicus
How does patent urachus present in an older male pt?
BPH –> bladder outflow obstruction –> increased pressure in bladder –> urachus opens
How is patent urachus differentiated from patent vitellointestinal duct which presents similarly?
Use small catheter to inject radio-visible dye and see what path it takes
What is a urachal cyst?
Urine filled cyst located at the umbilicus
What is exomphalos?
Umbilical defect where viscera are covered by peritoneum and amnion but are located outside of the body
What is gastoschisis?
Vertical herniation to the R of the umbilicus where viscera are not covered by peritoneum and amnion and are outside of the body
What type of pain can the pancreas and aorta cause and why?
Central back pain as they are retroperitoneal
What is referred pain?
Pain perceived at a site distant from the site of cause
Why is referred pain seen more commonly in children?
Brain is less developed
What causes somatic nerve pain?
Pain from noxious stimulus to proximal part of a somatic nerve –> perceived pain in distal dermatome of the nerve
Give an example of somatic referred pain.
Causeof pain in flank at T10 level –> felt at umbilicus
Give two causes of right iliac fossa pain due to somatic referred pain.
Shingles
R lower lobe pneumonia
What causes visceral referred pain?
In thorax and abdomen visceral afferent pain fibres follow sympathetic fibres back to same spinal cord segment that gave rise to preganglionic sympathetic fibres –> CNS perceives it as coming from somatic portion supplied by same spinal cord segment
How does appendicitis explain visceral referred pain?
Appendicitis pain –> visceral sensory nerve –> T10 spinal segment –> brain perceives pain as coming from T10 somatic sensory nerves –> umbilical pain
What causes visceral pain?
Ischaemia
Abnormally strong muscle contraction
Inflammation
Stretch
What stimuli do not cause visceral pain?
Touch
Burning
Cutting
Crushing
Where can gallbladder pain be felt?
Epigastrium
RUQ
Back
How do the embryonic divisions of the gut determine pain felt?
Foregut –> epigastric
Midgut –> periumbilical
Hindgut –> suprapubic
Where does the aorta bifurcate?
At umbilical level
How does the pain felt in acute appendicitis change as it progresses?
Early is referred visceral pain but as inflammation spreads to adjacent peritoneum which has somatic nerve supply –> localised somatic pain
How is small bowel colic pain felt?
Periumbilical pain which causes pts to double over and hold stomach due to waves which come every 35-40s
How is large bowel colic pain felt?
Waves of suprapubic pain every 2-3 mins which causes sufferers to hunch over
Why may renal/ureteric colic pain be referred to testicle/labia?
Descent in embryonic development
How is uterine and ovarian pain experienced?
Suprapubic pain which is localised to affected side if ovarian
Where is bladder pain experienced?
Suprapubic
Why can ruptured spleen/ectopic pregnancy/perforated ulcer cause shoulder pain?
If diaphragm is implicated the brain perceives pain as being in the shoulder due to dermatomes of C3,4,5
What is rectus abdominis?
Paired muscle which runs from ribs –> pubic symphysis which holds abdominal organs in place and aids posture
What is a hernia?
Protusion of part of the abdominal viscus through a defect in the abdominal wall
What forms the borders of Hesselbalch’s triangle?
Medial: rectus abdominis
Inferior: inguinal ligament
Lateral: inferior epigastric blood vessels
Describe the path of the inguinal canal.
Extends inferiorly and medially through inferior abdominal wall, superior and parallel to inguinal ligament from deep to superficial inguinal rings
What forms the roof of the inguinal canal?
Transversalis fascia
Internal oblique
Transversus abdominis
What forms the posterior wall of the inguinal canal?
Transversalis fascia
What forms the flow of the inguinal canal?
Inguinal ligament Lacunar ligament (medially)
What forms the anterior wall of the inguinal canal?
Aponeurosis of external oblique reinforced by internal oblique muscle laterally
What forms the superficial inguinal ring?
Evagination of external oblique which contains intercrural fibres parallel to external oblique aponeurosis fibres
Where is the mid-inguinal point?
1/2 way between public symphysis and ASIS
What is found at the mid-inguinal point?
Femoral artery
Where is the mid-point of the inguinal ligament and what is found here?
1/2 way between pubic tubercle and ASIS just below opening to inguinal canal
What is the transverse fascial sling?
Antero-superior crus and postero-superior crus which form a U-shaped ring around the deep inguinal ring
Where are common abdominal hernias located?
Epigastric
Umbilical
Inguinal
Femoral
What is an incisional hernia?
Improper healing of a surgical incision or scar –> site of herniation
What is an incarcerated hernia?
Hernia that cannot be massaged back into the abdomen due to swelling
What is a strangulated hernia?
Hernia with neck clamped –> necrosis of hernial sac and contents –> medical emergency
Are indirect or direct hernias more common?
Indirect
What is an indirect hernia?
Occurs at the deep inguinal ring –> through transversalis fascial sling –> extends along inguinal canal –> appears in scrotum or labium majora
What is a direct hernia?
Occurs in weak area of Hesselbalch’s triangle medial to vessels –> outpouching of strong conjoint tendon –> bulge in inguinal region
What causes indirect inguinal hernias?
Congenital due to failure of the processus vaginalis to regress with amount remaining determining degree of herniation
What are the S/S of indirect inguinal hernias?
Swelling
Pain in scrotum
Dragging sensation
What coverings does the peritoneal sac acquire in indirect inguinal hernia?
Same as the contents of the canal
What causes direct inguinal hernias?
Generally acquired seen in elderly with chronic conditions which increase intra-abdominal pressure long term e.g. COPD, bladder outflow obstruction, chronic constipation
What is the diagnostic sign of a direct inguinal hernia on CT scan?
Lateral crescent of fat
What can femoral hernias contain?
Preperitoneal fat
Omentum
Small bowel
Where are femoral hernias more common?
R sided predilection
More common in females
Where do femoral hernias arise?
Protrude inferior to epigastric vessels and medial to common femoral vein
What can lead to engorgement of distal collaterals veins seen in femoral but not inguinal hernias?
Neck of hernia below inguinal ligament with narrow funnel shape that can compress femoral vein
How does the relation to the pubic tubercle compare between inguinal and femoral hernias?
Femoral remain lateral, inguinal don’t
What can cause diaphragmatic hernias?
Developmental defects which allow any viscus to push through improperly developed diaphragm
Traumatic diaphragmatic rupture
Hiatus hernia
Are sliding or rolling hiatus hernias more common?
Sliding ~90%
Rolling ~10%
What is a sliding hiatus hernia?
Gastro-oesophageal junction slides into chest
What is a rolling hiatus hernia?
Gastro-oesophageal junction is in the normal position but the fundus of stomach moves into chest alongside oesophagus
What are the S/S of hiatus hernia?
Usually asymptomatic
Epigastric/chest pain
Post prandial fullness
N+V
What causes a congenital umbilical hernia?
Incomplete closure of the anterior abdominal wall after gut returns to the abdominal cavity in the 10th week of gestation
What are risk-factors for developing an umbilical hernia in adulthood?
Obesity
Multiparity
Ascites
Large intra-abdominal mass
What do umbilical hernias commonly contain?
Fat
Mesentery
Small +/- large bowel
What is Richter’s hernia?
Terminal ileum through a small defect in abdominal wall –> partial obstruction of bowel –> vomiting
What is visible on CT in Richter’s hernia?
Bowel loop on middle of the abdominal wall
What is Spigelian hernia?
Rare herniation along semilunar line through transversus abdominis aponeurosis close to arcuate line level
Why do S/S of Spigelian hernia vary?
Due to contents of hernial sac, degree and type of herniation and there is not typical pain associated
What does groin pain without a hernia suggest?
Repetitive strain of inguinal ligament
