What is the superior border of the anterolateral abdominal wall?
xiphoid process
costal margins
What is the inferior border of the anterolateral abdominal wall?
inguinal ligaments
pelvic girdle
What are the 9 anterior abdominal regions?
right hypochondriac, epigastric, left hypochondriac, right lateral, umbilical, left lateral, right inguinal, hypogastric (pubic), left inguinal
What are the 4 planes that divide the 9 abdominal regions?
2 horizontal: -subcostal -transtubercular 2 vertical -2 midclavicular planes, running inferiorly to midinguinal points
Describe the layers of the abdominal wall from superficial to deep.
- Skin
- Camper’s fascia (subcutaneous fat)
- Scarpa’s fascia (deep membranous layer)
- Investing (deep) fascia surrounding muscles
- External oblique muscle
- Internal oblique muscle
- Transverse abdominis
- Transversalis fascia
- Extraperitoneal fat
- Parietal peritoneum
What is the origin of the external obliques?
external surfaces of ribs 5-12
What is the insertion of the external obliques?
- linea alba
- pubic tubercle
- anterior half of iliac crest
What is the innervation of the external obliques?
- thoracoabdominal nerves (ventral rami T7-T11)
- subcostal nerve (T12)
What is the origin of the internal obliques?
- thoracolumbar fascia
- anterior 2/3 iliac crest
- CT deep to lateral 1/3 of inguinal ligament
What is the insertion of the internal obliques?
- inferior borders of ribs 10-12
- linea alba
- pecten pubis via conjoint tendon
What is the innervation of the internal obliques?
- thoracoabdominal nerves (ventral rami T6-T11)
- subcostal nerve (T12)
- L1
What is the origin of the transversus abdominis?
- internal surfaces of costal cartilages 7-12
- thoracolumbar fascia
- iliac crest
- CT deep to lateral 1/3 of inguinal ligament
What is the insertion of the transversus abdominis?
- linea alba
- pubic crest
- pecten pubis via conjoint tendon
What is the innervation of the transversus abdominis?
- thoracoabdominal nerves (ventral rami T6-T11)
- subcostal nerve (T12)
- L1
Where is the pyramidalis in relation to other abdominal muscles?
anterior to inferior part of rectus abdominus muscle;
attaches to anterior surface of pubis and anterior pubic ligament and ends in linea alba
What is the action of the pyramidalis?
tenses linea alba;
only present in 80% of people
What is the rectus sheath?
-incomplete fibrous sheath;
-compartment for rectus abdominis and pyramidalis;
formed by interweaving of apopneuroses of the flat muscles;
-creates linea alba
What forms the anterior layer of the rectus sheath?
interweaving of apopneurosis of external oblique and anterior laminae of internal oblique’s apopneurosis
What forms the posterior layer of the rectus sheath?
interweaving of posterior laminae of internal oblique’s apopneurosis and apopneurosis of transverse abdominal
Where does the rectus abdominis sit in relation to the rectus sheath?
in between anterior and posterior layers
What is the arcuate line?
demarcation of lower limit of posterior layer of rectus sheath;
inferior to umbilicus, all the muscle apopneuroses pass superficial to rectus abdominus muscle: all 3 apopneuroses now form anterior layer;
visible on posterior internal wall of rectus sheath
Describe the median fold of the interior abdominal wall.
runs from apex of bladder to umbilicus;
remnant of fetal urachus, which previously joined the bladder to the umbilicus
Describe the 2 medial folds of the interior abdominal wall.
remnants of fetal medial umbilical arteries, now occluded
Describe the 2 lateral folds of the interior abdominal wall.
protrude because of inferior epigastric vessels
What is the abdominal wall arterial supply?
- superior epigastric aa
- inferior epigastric aa
- intercostal and subcostal aa
- circumflex iliac aa
- superficial epigastric aa
Explain collateral venous return.
if either IVC is blocked, superficial and/or deep vein anastomoses are able to compensate
What is the system of collateral venous return specifically in the abdomen.
SVC -deep: superior epigastric vein -superficial: lateral thoracic vein IVC -deep: inferior epigastric vein -superficial: superficial epigastric vein
What are the thoracoabdominal nerves? Where are they in relation to the anterior abdominal muscles?
ventral rami of T7-T11;
anterior cutaneous and lateral cutaneous branches;
travel between internal obliques and transversus abdominis
Describe the branching of the L1 nerve.
L1 branches into:
- iliohypogastric nerve
- ilioinguinal nerve
What nerve innervates the umbilicus?
T10- serves as a good reference point
What 2 passages exist in the inguinal region?
- inguinal canal = passage to perineum
- subinguinal space = passage to lower limb
What forms the inguinal ligament? What is its location?
inferior edge of the external oblique muscle apopneurosis- curls up on itself;
forms a portion of inguinal canal;
runs from ASIS to pubic tubercle
Where is the subinguinal space? What passes thru it?
inferior to inguinal ligament; passing thru: -hip flexor muscles -femoral nerve -femoral sheath (femoral artery, femoral vein, femoral canal)
How is the inguinal canal formed?
by descent of gonads during development;
led by processus vaginalis
What forms the deep inguinal ring? Describe its location.
transversalis fascia;
superior to middle of inguinal ligament, lateral to inferior epigastric vessels
What forms the superficial inguinal ring? Describe its location.
apopneurosis of external obliques;
superolateral to pubic tubercle
What keeps the superficial inguinal ring from splitting apart?
intercrural fibers provide extra support when intra-abdominal pressure increases
What forms the anterior wall of the inguinal canal?
external oblique apopneurosis;
reinforced laterally by internal oblique apopneurosis
What forms the posterior wall of the inguinal canal?
transversalis fascia; conjoint tendon (formed by internal obliques and transversus abdominis)
What forms the roof of the inguinal canal?
arcing fibers of internal obliques and transversus abdominis
What forms the floor of the inguinal canal?
- iliopubic tract (thickened inferior margin of transversalis fascia)
- inguinal ligament
- lacunar ligament (inferior aspect of external oblique apopneurosis)
What are the contents of the inguinal canal in males vs. females?
both sexes:
- blood vessels, lymphatic ducts, ilioinguinal nerve
males: spermatic cord
females: round ligament of uterus
What aspect of the inguinal canal is palpable in both sexes?
superficial ring;
superior to pubic tubercle
Explain the formation of the inguinal canal in females.
1) ovaries attached to:
- posterior abdominal wall
- perineum via gubernaculum (path of descent)
2) descent is restricted by uterus and upper gubernaculum
In females, what does the gubernaculum become during formation of the inguinal canal?
upper gubernaculum: ovarian ligament
lower gubernaculum: round ligament of uterus
Explain the formation of the inguinal canal in males.
1) testes descend along path of gubernaculum and processus vaginalis
2) pulls peritoneum, abdominal muscles, and fascia along with it (EXCEPT transversus abdominis muscle, which splits at gubernaculum)
Describe the spermatic cord coverings and fascia from superficial to deep.
- skin
- external spermatic fascia from external oblique
- Cremaster muscle & fascia from internal oblique
- internal spermatic fascia from transversalis fascia
- tunica vaginalis from peritoneum (doesn’t descend into scrotum like other coverings)
What causes retraction of testicles?
contraction of Cremasteric muscle
Define: inguinal hernia.
protrusion of abdominal contents (peritoneum and small intestine) through abdominal wall;
more common in men
Define: indirect (congenital) inguinal herniation.
inguinal herniation thru inguinal canal;
pushes thru deep ring, LATERAL to inferior epigastric vessels;
can descend into scrotum along path of spermatic cord
Define: direct inguinal herniation.
inguinal hernation thru Hesselbach’s (inguinal) triangle;
pushes thru MEDIAL to inferior epigastric vessels;
can involve superficial ring if severe enough
What structures form Hesselbach’s (inguinal) triangle?
- lateral border of rectus abdominis medially
- inguinal ligament inferiorly
- inferior epigastric vessels laterally