anteriolateral abdominal wall Flashcards
what is the funciton of the abdominal wall?
encloses the abdominal cavity
what is contained within the abdominal cavity?
holds the bulk of the GI viscera
what is the function of the abdominal wall?
- forms a firm, flexible wall which keeps the abdominal viscera in the abdominal cavity
- PROTECTS abdo visceral from injury
- maintains ANATOMICAL POSITION of viscera against gravity
- assists in FORCEFUL EXPIRATION by pushing the abdominal viscera upwards
- involved in any action (coughing, vomiting) that INCREASES INTRA-ABDOMINAL pressure
what are the layers of the abdominal wall? (external to internal)
skin, superficial fascia (subcutaneous tissue), muscles & associated fascia, parietal peritoneum
what does the superficial fascia consist of?
fatty connective tissue
what does the composition of the superficial fascia layer depend on?
its location
describe how the superficial fascia layer is above the umbilicus?
a single sheet of connective tissue
continuous with the superficial fascia in other regions of the body
describe how the superficial fascia layer is below the umbilicus?
divided into 2 layers:
fatty superficial layer (Camper’s fascia)
membranous deep layer (Scarpa’s fascia)
what runs between the 2 superficial fascia layer below the umbilicus?
superficial vessels and nerves
how many muscles are there in the abdominal wall?
5 muscles
what are the groups that the muscles in the abdominal wall can be divided into?
vertical muscles & flat muscles
how many flat muscles of the abdominal wall are there?
3 flat muscles:
external oblique
internal oblique
transversus abdominis
where are the flat muscles of the abdominal wall located?
laterally in the abdominal wall, stacked upon one another
What is the function of the flat muscles?
they act to flex, laterally flex and rotate the trunk
which direction do the fibres of the abdominal wall run? why?
in differing directions and cross each other - strengthening the abdominal wall and decreasing the risk of herniation
describe the muscle external oblique in terms of structure within the abdominal wall
largest and most superficial flat muscle
where do the fibres of external oblique run? what does it form?
fibres run inferomedially
as the fibres approach the mid-line, they form an aponeurosis
what is an aponeurosis?
a broad flat tendon
what happens in the mid-line where the aponeuroses forms?
the aponeuroses of all the flat muscles become entwined, forming the linea alba
what is the linea alba?
a fibrous structure that extends from the xiphoid process of the sternum to the pubic symphysis
describe the location of the internal oblique muscle within the anterolateral abdominal wall
lies deep to the external oblique
smaller and thinner structure
where do the fibres of the internal oblique run?
superiormedially (perpendicular to the fibres of the external oblique)
what happens to the fibres of internal oblique near the midline?
forms aponeurotic fibres which contribute to the linea alba
Where does the transversus abdominis lie within the anterolateral abdominal wall?
deepest of the flat muscles
where do the fibres of transversus abdominis lie?
transversely running fibres
does the transversus abdominis contribute to linea alba?
transversus abdominis contributes to aponeurotic fibres to the linea alba (like other flat muscles)
what lies deep to transversus abdominis?
a well formed layer of fascia, called transversalis fascia
what are the vertical muscles?
rectus abdominis
pyramidalis
what and where is the rectus abdominis?
a long, paired muscle, found either side of the midline in the abdominal wall
what is the rectus abdominis split into 2 by?
linea alba
what do the lateral border of the 2 muscles create?
a surface marking called the linea semilunaris
what is the rectus abdominis intersected by at several places?
a fibrous strip - tendinous intersections
what gives the 6 pack appearances?
the tendinous intersections and the linea alba
in individuals with low body fat
what are the functions of the rectus abdominis?
compressing abdominal viscera
stabilise pelvis during walking
depresses the ribs
describe the pyramidalis
a small triangle shaped muscle
where is the pyramidalis found?
lovated inferiorly
base on pubis bone
apex of triangle attached to linea alba
what is the function of pyramidalis?
tense the linea alba
what is the rectus sheath formed by?
by the aponeuroses of the 3 flat muscles, and enloses the rectus abdominus and pyramidalis muscles
has anterior & posterior wall for most of its length
what forms the anterior wall of the rectus sheath?
aponeuroses of the external oblique, and of half of the internal oblique
what forms the posterior wall of the rectus sheath?
formed by the aponeuroses of half the internal oblique and of the transversus abdominis
does the aponeuroses move? to where? when?
approximately halfway between the umbilicus and the pubic symphysis, all of the aponeuroses move to the anterior wall of the rectus sheath
what happens when the aponeuroses moves to the anterior wall of the rectus sheath?
there is no posterior wall to the sheath
the rectus abdominis is in direct contact with the transversalis fascia
what is the arcuate line?
the area of transition between having a posterior wall and on posterior wall
which factors should be considered in incision used to gain access to the abdominal cavity?
- direction of the muscle fibres (split muscle fibres rather than cut)
- location of nerves
- ease of access of the desired viscera
what is the median vertical incisions?
an incision that is made through the linea alba
can be extended the whole length of the abdomen, by curving around the umbilicus
why is blood loss minimal in median vertical incisions?
what is another advantage of median vertical incisions?
linea alba is poorly vascularised
major nerves are also avoided
when is median vertical incision used?
access to abdominal cavity
what is paramedian vertical incisions
similar to median incision, but is performed laterally to the linea alba, providing access to more lateral structures (kidney, spleen & adrenals)
where is a transverse incision made?
an incision made just inferior and laterally to the umbilicus
why is a transverse incision made?
causes least damage to the nerve supply to the abdominal muscles, and heals well
what is produced when incised rectus abdominis heals?
the incised rectus abdominus heals producing a new tendinous intersection
when is a transverse incision used?
in operations on the colon, duodenum & pancreas
where is suprapubic transverse incision (pfannenstiel) made?
5cm superior to the pubis symphysis
when are suprapubic transverse incisions made?
when access to the pelvic organs is needed
what care must be taken in a suprapubic transverse incision?
care must be taken not to perforate the bladder (especially if it is not catheterised), as the fascia thins around the bladder area
where is subcostal transverse incision made?
the incision starts inferior to the xiphoid process, and extends inferior parallel to the costal margin
when is subcostal transverse incision made?
used on the right side to operate on the gall bladder, and on the left to operate on the spleen
how is a McBurney transverse incision made? what does it allow for?
a ‘grid iron’ incision, because it consists of 2 perpendicular lines, splitting the fibres of the muscles without cutting them - allows for excellent healing
where is a McBurney transverse incision made?
performed at McBurney’s point (1/3 of the distance between the ASIS and the umbilicus)
when is a McBurney transverse incision made?
appendectomies
