anatomy of the abdominal wall and peritoneum Flashcards
what are the borders of the abdominal wall?
superior - the xiphoid process of the sternum & coastal cartilages
inferior - iliac crest & public bones of the pelvis
anterior - the abdominal muscles
posterior - the spine
what are the lines dividing the abdominal area?
midclavicular x2
transpyloric plane
inter-tubercular plane
what are the 9 abdominal regions?
TOP 1/3
right hypochondriac, epigastric, left hypochondriac
MID 1/3
right lumbar/flank, umbilical, left lumbar/flank
BOTTOM 1/3
right iliac, hypogastric/suprapubic, left iliac
where is the transpyloric plane (of Addison)
- Midway between the pubic synthesis and the jugular notch
- Runs from the tip of the 9th costal cartilage
- at approximately the level of L1 vertebral body
- it is the point where the midclavicular line crosses the costal margin?
where is McBurney’s point?
- between the umbilicus and the anterior superior iliac spine (ASIS) on right side
- it lies 2 thirds of the way along this line, over the iliac fossa.
- It is where the base of the appendix usually lies (tender in acute appendicitis)
what are the 4 layers of the abdominal wall?
- Skin
- Superficial fascia: Fatty connective tissue
- Muscles and associated fascia
- Parietal peritoneum
how many Anterior abdominal wall muscles are there?
- 3 Pairs of flat muscles
- 2 pairs of vertical muscles
name the 3 flat muscles of the anterior abdominal wall?
- external oblique
- internal oblique
- transversus abdominis
where does the external oblique originate and insert?
originates from lower ribs (5-12)
insertions
- iliac crest
- pubic bone (crest, symphysis, tubercle)
- becomes aponeruiosis ( xiphoid process and the linea alba)
what are the functions of the external and internal obliques?
- Contralateral rotation of the torso.
- flexion of the trunk
- Bilateral contraction of EO, rectus abdominis and IO - this flexes the trunk by drawing the pubis towards the xiphoid (like in crunches or sit-ups)
where does the internal oblique originate and insert?
ORIGINS:
- the inguinal ligament,
- iliac crest
- the lumbodorsal fascia
INSERTIONS:
- ribs 10-12,
- costal cartilages,
- becomes Aponeurosis: Xiphoid process, pubic tubercle, linea alba, pubic synthesis
which of the flat muscles is deepest? which is largest?
EO - largest
IO - deep to EO, smaller and thinner
transversus abdominis - deepest
what direction to each of the flat muscles fibres run?
EO - ‘hands in pockets’ inferomedially
IO - superomedially, perpendicular to EO
transversus abdominis - horizontally
what is the innervation of the flat muscles?
- Thoracoabdominal nerves (T7-T11)
- subcostal nerve (T12).
IO and transversus abdominis:
- additionally innervated by branches of the lumbar plexus.
what is the function of the transversus abdominis?
Compression of abdominal contents.
what are the origins and insertions of the transversus abdominis?
origins - the inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia.
insertions - the conjoint tendon. Aponeurosis: Xiphoid process, pubic tubercle, linea alba, pubic synthesis
what is the aponeurosis in the anterior abdominal wall?
- each flat muscle forms an aponeurosis (broad flat tendon tissue that anchors muscles) near to midclavicular line
- aponeurosis of each flat muscles connects with its pair on other side of midline
- the aponeurosis covers the vertical rectus abdominis muscle
what is the white central line extending from the xiphoid process of the sternum to the pubic symphysis called? what is it made of?
- the linea alba
- a fibrous structure
- formed from the aponeuroses of all the flat muscles where they meet in the midline
name the 2 vertical muscles
- rectus abdominis
2. pyramidalis
what are the origins and insertions of the rectus abdominis?
origins - pubic crest
insertions - xiphoid process, costal cartilage of ribs 5-7
what are the origins and insertions of the pyramidalis?
origins - pubic crest and pubic symphysis
insertions - the linea alba
what is the function of the rectus abdominis?
- compressing the abdominal viscera,
- stabilises the pelvis during walking,
- depresses the ribs
what is the function of the pyramidalis?
to tense the linea alba.
what is the innervation for the vertical muscles?
rectus abdominis - Thoracoabdominal nerves (T7-T11).
pyramidalis - Subcostal nerve (T12).
which is the bigger of the vertical muscles? describe their shapes?
rectus abdominis - long, paired muscle, found either side of the midline in the abdominal wall
pyramidalis- small triangular muscle, found superficially to the rectus abdominis.
what is thelinea semilunaris?
surface marking created by the lateral borders of the rectus abdominis muscles
what is the blood supply to the vertical muscles?
Inferior epigastric arteries (+ superior for pyramidalis)
what makes up the ‘6 pack’?
The rectus abdominis muscle, the tendinous intersections of this muscle, and the linea alba
what muscles is the rectus sheath formed from?
the aponeuroses of the 3 flat muscles (EO,IO,transversus abdominis)
what muscles does the rectus sheath enclose?
the 2 vertical muscles ( rectus abdominis, pyramidalis)
describe the rectus sheath layers in the upper 2/3 of the abdomen?
The anterior wall - is formed by the aponeuroses of the external oblique, and of half of the internal oblique. (1.5 layers)
The posterior wall- is formed by the aponeuroses of half the internal oblique and of the transversus abdominis.
(1.5 layers)
anterior/posterior to rectus abdominis muscle (enclosed)
describe the rectus sheath layers in the lower 1/3 of the abdomen?
anterior wall - formed by all the aponeuroses (EO,IO,transversus abdominis)
posterior wall - none (in direct contact with the transversalis fascia)
what line divides the upper 2/3 from the lower 1/3 of the abdomen?
the arcuate line
- Approximately midway between the umbilicus and the pubic symphysis
what arteries supply the abdominal wall?
- epigastric (sup + inf)
- segmental lumbar arteries
- Intercostal arteries
what veins drain the abdominal wall?
- Intercostal veins drain into the azygos system
- Lumbar veins drain to the veins of the posterior abdominal wall and the azygos system
- Superior and inferior epigastric veins drain to subclavian and femoral veins respectively
what is the peritoneum?
a continuous membrane which lines the abdominal cavity and covers the abdominal organs
what is the role of the peritoneum?
- support the viscera/organs
- providespathways for blood vessels and lymph to travel to and from the viscera.
what are the 2 layers to the peritoneum?
- visceral (lines the organs)
- parietal (lines the wall)
what epithelium lines the peritoneum?
- simple squamous epithelial cells
- called mesothelium
- same for both layers
what derived the 2 layers of the peritoneum in the embryo?
pariteal - somatic mesoderm
visceral - splanchnic mesoderm
what is the nerve supply of the parietal peritoneum? how does this affect pain sensation?
- same somatic nerve supply as the region of the abdominal wall is lines
- so well localised pain
what is the nerve supply of the visceral peritoneum? how does this affect pain sensation?
has the sameautonomicnerve supply as the viscera it covers
- pain is poorly localised
- pain is referred to dermatomes
what are the 2 functions of the peritoneal cavity (potential space)?
- the peritoneal fluid acts as a lubricant to enable free movement of abdominal viscera/organs ]
- contains antibodies to fight infection
what are intraperitoneal organs?
give examples
- if they are enveloped by visceral peritoneum anteriorly and posteriorly
eg. stomach,spleen,liver
what are retroperitoneal organs?
- when organs are not covered in visceral peritoneum
- only parietal peritoneum on their anterior surface
what is the difference between primary and secondary retroperitoneal organs?
primary - developed as retroperitoneal (oesophagus, rectum and kidneys)
secondary - initially intraperitoneal (ascending and descending colon)
what abdominal organs are retroperitoneal ?
SAD PUCKER
Suprarenal glans (adrenal) Aorta & IVC Duodenum Pancreas Ureters Colon (asc,desc) Kidneys Eosophagus Rectum
what is a mesentery?
= double layer of visceral peritoneum
what are the roles of the mesenteries?
connects intraperitoneal organs to posterior abdominal wall
carries blood vessels, nerves, lymphatics
absorbs nutrients
what organ is the main mesentery connected to?
- the small intestine
what is an omentum?
omenta =
- sheets of visceral peritoneum
- that extend from thestomach and proximal part of the duodenum to other abdominal organs.
what is the role of the GREATER omentum?
how many layers is it?
= 4 visceral peritoneum layers
- attaches to GREATER curvature of stomach + proximal duodenum + transverse colon
- migrates to infected viscera
- contains lots of lymph’s and vessels
what is the role of the LESSER omentum?
what are its attachments?
= a double layer of visceral peritoneum (smaller then great)
- attaches from thelesser curvatureof the stomach and the proximal part of the duodenum to the liver.
what 2 ligaments does the lesser omentum contain?
- the hepatogastric ligament
(flat broad sheet) - the hepatoduodenal ligament
(free edge)
what important vessels does the lesser omentum contain?
what organ do they supply?
the portal triad
- hepatic artery
- portal vein
- bile dict
within the hepatoduodenal ligament (the free edge)
provides blood suppply to liver
what is a peritoneal ligament?
- the double fold of peritoneum that connects the viscera to another viscera or the abdominal wall
what is the falciform ligament?
- sickle shaped
- attaches anterior surface of liver to anterior abdominal wall
- its free edge contains the ligamentum teres
what is the ligamentum teres ?
a remanent of the umbilical vein (oxygenated blood from placenta to fetus)
on the free edge of the falciform ligament
what is the urachus?
- fibrous cord
- remnant of a channel between the bladder and the umbilicus
what is a dermatome?
- area of skin
- which is supplied by the same sensory ganglia and spinal cord segments as the nerve fibres innervating the viscera
eg. Irritation of thediaphragm(e.g. as a result of inflammation of the liver, gallbladder or duodenum) may result inshoulder tip pain.