anatomy of the GI tract Flashcards
what is the anterior, lateral, and posterior walls of the abdomen are composed of?
skin, subcutaneous tissue and muscles and their associated aponeuroses (flat tendons)
what are the functions of the abdominal wall?
- protect the abdominal viscera
- increase intra-abdominal pressure (e.g. for defecation and childbirth)
- maintain posture and move the trunk
what is the name of the serous membrane that lines the internal abdominal wall?
parietal peritoneum
how is the abdominal region be split into 9 parts?
four imaginary lines:
* the right and left midclavicular lines
* the subcostal line: underneath the most inferior part of the costal margin
* the intertubercular line: a horizontal line drawn through the tubercles of the right and left iliac crests
what are the names of the 9 regions in which the abdomen can be split into?
superior right to left: right hypochondrium
middle right to left: right flank, umbilical region, left flank
inferior right to left: right iliac fossa, suprapubic region, left iliac fossa
where is the transpyloric plane?
lies halfway between the superior border of the manubrium and the pubic symphysis; a horizontal line that passes through the tips of the right and left ninth costal cartilage
what does the transpyloric plane transect?
the pylorus of the stomach, the gallbladder, the pancreas and the hila of the kidneys
where is the transumbilical plane?
going across the belly button (umbilicus)
where is the intercristal plane?
a horizontal line drawn between the highest points of the right and left iliac crests used to guide procedures on the back (e.g. lumbar puncture)
where is McBurney’s point?
lies two thirds of the way along a line drawn from the umbilicus to the right anterior superior iliac spine, and is the surface marking of the base of the appendix
what are the four pairs of muscles in the anterolateral abdominal wall?
- external oblique (diagonally orientated fibres)
- internal oblique (diagonally orientated fibres)
- transversus abdominis (horizontally orientated fibres)
- rectus abdominis (rectus = straight).
how do the fibres of the external obliques lie?
run medially and inferiorly, towards the midline
how do the fibres of the internal obliques lie?
are orientated perpendicular to those of EO (they run medially and superiorly)
where does the transversus abdominis lie and how are the fibres orientated??
deep to the internal oblique, horizontally
what happens when the muscles of the abdomen contact?
increase intra-abdominal pressure
what are the lateral flexors of the lumbar spine?
oblique muscles
what do the muscles of the abdomen become anteriorly?
a flat tendon aponeurotic forming a ‘white line’ called linea alba
what is the rectus sheath and what is it formed from?
encloses the rectus abdominis, formed from the aponeuroses of abdominal muscles
what forms the anterior wall of the rectus sheath?
the anterior layer of the internal oblique aponeurosis and the externa oblique
what forms the posterior wall of the rectus sheath?
posterior layer of the IO aponeurosis and the transversus abdominis aponeurosis
what lies deep to the transverse abdominis?
transversalis fascia
what lies deep to the transversalis fascia?
parietal peritoneum
what arteries supply the anterolateral abdominal wall>
- musculophrenic artery, a branch of the internal thoracic
- superior epigastric artery, which is the continuation of the internal thoracic artery. It descends in the rectus sheath
- inferior epigastric artery, a branch of the external iliac artery. It ascends in the rectus sheath and anastomoses with the superior epigastric.
what is the innervation of the anterior abdominal wall?
● thoraco-abdominal nerves T7 – T11. These are essentially the continuation of the intercostal nerves T7 – T11. These somatic nerves contain sensory and motor fibres.
● the subcostal nerve – this originates from the T12 spinal nerve (so called because it runs along the inferior border of the 12th rib).
● iliohypogastric and ilioinguinal nerves – both are branches of the L1 spinal nerve.