abdomen anatomy

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The Abdomen
Surface Anatomy, Muscles and
Peritoneum

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Abdominopelvic Cavity
Largest part of ventral body
cavity
Abdominal
Stomach, liver, kidneys, etc
Pelvic
Bladder, some reproductive
organs, rectum
Two cavities are continuous
pg 12

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Surface Anatomy of Abdomen
Umbilicus = navel
Linea alba = white line
Xiphoid process to
pubic symphysis
Tendinous line
Inferior Boundaries
Iliac crest
Ant. Sup. Iliac spine
Inguinal ligament
Pubic crest
Superior Boundary
Diaphragm
pg 742
Pg 187

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Four Abdominal Quadrants
Pg 16

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Muscles of Abdominal Wall
No bony reinforcement
3 sheet-like layers
Continuous with layers
of intercostal muscles
Fibers of layers run in
different directions for
strength
Ends in aponeurosis
which contains rectus
abdominis muscle
Function: hold in organs,
move trunk, forced
breathing, inc. intra-
abdominal pressure
pg 278

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Muscles of Anterior Abdominal Wall
External Obliques
O: lower 8 ribs I: aponeurosis to linea alba
Function: Flex trunk, compress abd. wall (together)
Rotate trunk (separate sides)
Internal Obliques
O: Lumbar fascia, iliac crest, inguinal ligament
I: Linea alba, pubic crest, last 3-4 ribs, costal margin
Function: Same as External obliques
Transversus Abdominis
O:same as Internals, plus last 6 ribs
I: Xiphoid process, costal cart. 5-7
Function: Compress abdomen
Rectus Abdominis
O: Pubic crest, pubic symphysis I: Xiphoid, cost cart 5-7
Function: Flex, rotate trunk, compress abdomen, fix ribs

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Muscles of the
Anterior
Abdomen Wall
All muscles of anterior abdomen innervated by INTERCOSTAL nerves

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Muscles of the Posterior Abdominal Wall
Iliopsoas
Psoas major
O: Lumbar vertebrae + T12
I: Lesser trochanter of femur via iliopsoas tendon
Function: Thigh flexion, trunk flexion, lateral flexion
Iliacus
O: Iliac fossa, ala of sacrum
I: Lesser trochanter of femur via iliopsoas tendon
Function: Thigh flexion, trunk flexion
Quadratus lumborum
O: iliac crest, lumbar fascia
I: trans. proc of upper lumbar vertebrae
Function: Flex vertebral column

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Muscles of
Posterior
Abdominal
Wall
Quadratus
lumborum
Iliiopsoas
Iliacus
Psoas major
Pg 299

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Peritoneum
Extension of serous membrane in the
abdomino-pelvic cavity
Mesentery: Double layer of peritoneum
Hold organs in place
Store fat
Route for vessels + nerves
Retroperitoneal: some organs behind
peritoneum (eg) duodenum, ascending +
descending colon, rectum, pancreas
Peritoneal: remain surrounded by peritoneal
cavity (eg) liver, stomach, ileum + jejunum

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Peritoneal vs Retroperitoneal
Pg 13, 614