Anterior Abdominal Wall, Inguinal Canal, and Scrotum (Part 1: Anterior Abdominal Wall) Flashcards
2 parts of abdominopelvic cavity
1) abdominal cavity proper (orange)
2) pelvic cavity (false pelvis) (green)
where does the abdominal cavity end and the pelvic cavity begin?
At the pelvis inlet (pelvic aperture)
Superior border of the abdominal cavity:
Superior border: diaphragm and costal margin (ribs 7-10) + 11th and 12th ribs
Inferior border of the abdominal cavity
Inferior border: Pelvic inlet (pelvic brim)
Anterior and lateral border of abdominal cavity
Anterior and lateral border: skin, fascia, and muscles (musculo-aponeurotic)
Posterior border of the abdominal cavity:
Posterior border: lumbar vertebral column, back muscles, diaphragm that overlies the thoracic vertebrae and lower ribs
A =
B =
C =
D =
E =
F =
G =
A =
B =
C =
D =
E =
F =
G =
H =
I =
tendinous intersections
tendinous intersections run horizontally across each rectus abdominis muscle
anterior superior illiac spine (ASIS)
a sharp notch anterior to the iliac crest.
Inguinal ligament
seperates abdominal wall from the thigh
- fibrous band that extends from the anterior superior iliac spine laterally to the pubic tubercle medially.
- Formed by the lower free border of the external oblique aponeurosis, which folds upon itself.
- The internal oblique and transversus abdominis muscles originate from its lateral end.
Superficial (external) inguinal ring
-location/general definition
- a triangular opening of the inguinal canal
- in the external oblique aponeurosis
- lies just lateral to the pubic tubercle
semilunar line
a curved vertical line on the anterior abdominal wall at the lateral edge of each rectus abdominis muscle
linea alba
- midline
- a tendinous median line that extends from the xiphoid process to the pubic symphysis
- Formed by the fusion of the aponeuroses of the external oblique, internal oblique, and transversus abdominismuscles.
A =
A= median plan e (right and left halves) = midline
B =
B = midclavicular/mid-inguinal planes (midpoint of clavicle and inguinal)
C =
C = transpyloric plane (L1 vertebra)
D =
D = subcostal plane (10th costal cartilage)
(end of costal margin)
E =
E = transumbilical plane (L3/L4 vertebra)
(goes through umbilicus)
F =
F = supracristal plane (L4 vertebral body)
(at uppermost point of iliac crest)
G =
G = transtubercular plane (L5 vertebral body)
Passes through the iliac tubercles and body of the L5 vertebra.
H =
H = interspinous plane
-passes between left and right ASIS
1 =
(and contents)
1 = right hypochondriac
contains: liver, gallbladder, right kidney, small intestine
2 =
(and contents)
2 = Left hypochondriac
contains: spleen, colon, left kidney, pancreas
3 =
(and contents)
3 = epigastric
contains: stomach, liver, pancreas, duodenum, spleen, adrenal glands
4 =
(and contents)
4 = right lateral lumbar
contains: gallbladder, liver, ascending right colon, right kidney, small intestine
5 =
(and contents)
5 = left lateral lumbar
contains: descending colon, left kidney, small intestine
6 =
(and contents)
6 = umbilical
contains: umbilicus, stomach, pancreas, small intestine, duodenum, transverse colon
7 =
(and contents)
7 = right inguinal (groin)
contains: small intestine, appendex, cecum, ascending colon
8 =
(and contents)
8 = left inguinal (groin)
contains: small intestine, sigmoid colon, descending colon
9 =
(and contents)
9 = pubic (hypogastric)
contains: small intestine, sigmoid colon, bladder
5 most common types of hernias
1) inguinal (most common overall)
2) umbilical (congenital or aquired)
3) incisional
4) epigastric
5) spigelian
why do inguinal hernias occur?
- the inguinal area is weak because the structures entering between then abdomen and thigh (transversalis fascia)
- Commonly secondary to conditions resulting in increased intraabdominal pressure (e.g., chronic obstructive pulmonary disease with chronic coughing, constipation)
- 2 types: direct and indirect
2 types of umbilical hernias and why they occur
1) congenital (common in neonates) - occur because of conntevt between fetus and mother
2) aquired (common in pregnant women and obese people) - occur because of intrabdominal pressure
why do incisional hernias occur?
Herniation of intra-abdominal contents through an abdominal wall defect created during a previous abdominal surgery.
where do epigastric hernias occur and why?
occur in midline between xiphoid process and the umbilicus (in linea alba)
(type of ventral hernia)
(can occur if problem with linea alba)
spigelian hernia
(where do they occur)
occur along semilunar lines
not very common
endoabdominal fascia - why is it important?
- surgical plane to seperate abdominal wall
- provides a plane that can be opened, enabling the surgeon to appraoch structures on or in the anterior aspect of the posterior abdominal wall (kidneys, bodies of lumbar vertebra, ect) withoutout entering th emembranous perioneal sac containing the abdominal viscera
- thus, the risk of contamination is minimized
A =
a = camper’s fascia = superficial fatty layer
(C comes before S - so remember camper’s before scarpa)
b =
b = scarpa’s fascia = deep membranous layer
(C comes before S - so remember camper’s before scarpa)
c =
c = extraperitoneal fat
d =
d = parietal peritoneum
- component of peritoneum that lines the abdominopelvic cavity.
- Receives somatic innervation and is pain sensitive.
e =
e = endoabdominal fascia = transversalis fascia (deep fascia)
- continuation of endothoracic fascia
- important surgical plane to seperate abdominal wall
f =
f = transversus abdominus muscle
g =
g = internal oblique muscle
h =
h = external oblique muscle
I =
I = investing fascia (deep fascia, encloses all muscles)
6 main functions of abdominal wall muscles:
1) maintenance of posture
2) assist in respiration (because change in abdominal pressure)
3) moving the trunk and stabilizing the pelvis
4) support and protect abdominal viscera
5) accommodate expansion/flexibility (pregnancy, weight gain)
6) expulsion of fluid (urine or vomitus), flatus, feces of fetuses (when increase in abdominal wall pressure)
External oblique
- location
- fiber orientation
- origin
- inserts
- most superficial abdominal muscle
- fiber orientation: inferomedially (hands in pocket) (downward and medially)
- origin: lower 8 ribs
- inserts: iliac crest, pubic tuburcle, linea alba
Internal oblique muscle
- location
- origin
- fiber orientation
- inserts
- intermediate abdominal muscle
- fibers are orientated perpindicular to external oblique muscles (medially and superior)
- origin: iliac crest and inguinal ligament
- inserts: lower 3 ribs, linea alba, pubis
transverse abdominis muscle
- location
- fiber orientation
- origin
- inserts
- deepest abdominal muscle
- run in transverse orientation
- origin: lower 6 costal cartilages, iliac crest, and inguinal ligament
inserts: linea alba, pubis (via conjoint tendon)
rectus abdominis
- location
- fiber orientation
- origin
- inserts
- enclosed within the rectus sheath (fibers of aponeurosis of 3 flat muscles)
- fibers run in a vertical direction (straight, anteriorly)
- origin: pubis
- inserts: xiphoid process, costal cartilages (riibs 5-7)
pyramidalis
- location
- origin
- inserts
- triangular muscles lies anterior to inferior part of rectus abdominis with in the rectus sheath
- origin: pubis, pubic ligament
- inserts: linea alba
*found inferiorly, but can be abscent in some individuals (very small)
rectus sheath (what does it consist of/enclose)
a sheath formed by the fusion of aponeuroses (broad tendons) of the flat muscles (external oblique, internal oblique, and transversus abdominis muscles), which encloses the vertical muscles (rectus abdominis and pyramidalis muscles)
arcuate line
- terminal point at theh posterior layer of the rectus sheath (so below this line, no posterior layer of rectis sheath)
- a line which allows inferior epigastric vessels to enter into the rectus sheath (The inferior epigastric vessels perforate the rectus abdominis here.)
- the arrangement of the aponeurosis (rectus sheath) is different above and below the arcuate line
above arcuate line:
Anteriorly: Aponeurosis of EO
- Posteriorly: Aponeurosis of TA
- IO splits in two:
- part comes anterior to rectus abdominis (anterior)
- part comes posterior to rectus adominis (posterior)
below arcuate line:
-all aponeurposis from EO, IO and TA are anterior to rectus abdomiinis
(so no posterior rectal sheath)
-instead have transversalis fascia, extraperioneal fat and parietal peritoneum anteriorly
at arcuate line:
-TA aponeurosis and the posterior lamina of the IO aponeurosis pass anterior to the rectus muscle. -Thus, the lower 1/3rd of the rectus muscle is in direct contact with the peritoneum.
contents of rectus sheath
*remember by rule of 2
abdominal muscles:
- rectus abdominis
- pyrimidalis
abdominal viscera:
- superior epigastric
- inferior epigastric
abdominal nerves: (lower 6 intercostal nerves)
- lower five intercostal nerves (T7-T11)
- subcostal nerve (T12)
anterior abdominal wall muscles (and mneumonic)
TIRE Pump
Transversus abdominis
Internal abdominal oblique
Rectus abdominis
External abdominal oblique
Pyramidalis
abdominal vessels in rectus sheath (where they come from/what they supply/landmarks)
superior epigastric
- branch of the internal thoracic artery
- descends along the abdominal wall and anastomoses with branches of the inferior epigastric artery near the umbilicus
- supplies the anterior abdominal wall.
inferior epigastric
- Branch of external iliac artery
- Main artery of the lower abdominal wall
- Anastomoses with superior epigastric artery
- Gives rise to the cremasteric artery (runs in spermatic cord)
- Forms lateral boundary for Hesselbach’s triangle
*Superior epigastric artery and inferior epigastric artery anastomose, providing collateral circulation between the subclavian and external iliac arteries
Nerves in rectus sheath
1) lower five intercostal nerves (T7-T11)
2) subcostal nerve (T12)
* The lower five intercostal nerves pierce the lateral margin of the linea semilunaris to enter the rectus sheath posterolaterally. The intercostal (T6–T9), subcostal, and L1 nerves terminate in the rectus abdominis muscle with three patterns:*
* (1) terminate simply within the muscle,*
* (2) supply the muscle and then terminate as a cutaneous branch, or*
* (3) pass through the muscle and terminate as a cutaneous branch*
