Session 3 - The mesenteries Flashcards
What is the vitelline duct?
- A duct which leads to yolk sac
* Persistence leads to a number of different abnormalities
What is a patent vitellintestinal duct?
• Joins small intestine to umbillicus
What is a vitelline cyst?
• Vitelline duct forms fibrous strands at either end
What is a vitelline fistual?
• Direct communication between the umbilicus and the intestinal tract
Faecal matter comes out of umbilicus
What is the allantois?
• Placental exchange barrier
What occurs in a patent urachus?
Joins bladder to umbilicus
When can a patent urachus occur?
• Birth or later in life when men develop bladder outflow obstruction due to benign prostatic hypertrophy
What is Meckel’s diverticulum?
- Most common GI abnormality
* Cul-de-sac in the ileum
What is the rule of 2’s for Meckel’s diverticulum?
• Effects 2% people, 2 feet from the iliocecal valve, 2 inches long, 2 types of tissue - Small bowel epithelium, gastric epithelium (Why?), 2:1 males to females
What is gastroichis?
- Failure of closure of the abdominal wall during folding of the embryo, leaving gut tub eand its derivatives outside the body cavity
- Viscera not covered by peritoneum
What is an omphalocoele?
- Persistence of physiological herniation
* Part of gut tube fails to return to abdominal cavity following normal herniation into abdominal cord
What is somatic referred pain?
- Pain caused by a noxious stimulus to the proximal part of a somatic nerve that is perceived in the distal dermatome of the nerve
- E.g. Shingles - pain felt distally along the nerve
What is visceral referred pain?
- In the thorax and abdomen, visceral afferent pain fibers follow sympathetic fibres back to the same spinal cord segments
- CNS perceives visceral (gut) pain as coming from superficial, somatic portions of the body supplied by relevant spinal cord segments
Give four factors which cause visceral referred pain
- Ischaemia
- Abnormally strong muscle contraction
- Inflammation
- Stretch
Give four usually painful stimuli which do not cause referred pain
- Touch
- Burning
- Cutting
- Crushing
Define referred pain
• Pain perceived at a site distant from the site causing the pain
What is the vertebral level of the umbilicus?
T10
What is the vertebral level of the pelvic brim?
T12
Give two causes of referred pain?
- Shingles
* Right lower lobe pneumonia
Where can visceral foregut pain refer?
• Epigastric region
Where can midgut pain refer?
• Periumbilical region
Where can hindgut pain refer?
• Suprapubic region
What can damage to retroperitoneal structures cause?
• Central back pain
Where does early appendicitic pain localise?
• Umbilicus
Why does early appendicitic pain appear in the umbilicus?
• Innervation of appendix enters spine at T10
What does pain localise to lower quadrant in late stage appendicitis?
• Appendix becomes more inflamed and irritates surrounding bowel wall, localising the pain the right lower quadrant (irritates somatic nerve)
What is the anterior abdominal wall composed of?
• Skin, fasciae and muscle
Where does the anterior abdominal wall extend to and from?
• Anterior aspects of the rib cage and pelvic wall
What is knowledge of the composition of the abdominal wall used for?
• Surgical procedures
How many muscles are there in the antero-lateral abdominal wall?
- 3 flat
* 2 vertical
Where do the flat muscles on either side of the abdomen interlace?
• At the linea alba
What movements are the muscles of the abdomen useful for?
- Flexing
- Twisting
- Lateral flexion of the trunk
Other than movement, give one use of the abdominal muscles?
• Forced expiration during coughing
What does the location of a surgical incision depend on? (4)
- Type of surgical incision
- Location of abdominal viscera
- Avoidance of nerves
- Maintenance of blood supply
Where does small bower colic localise?
• Midgut, periumbilical
Give a cause of supapubic (hindgut pain)
• Large bowel colic