Muscles of Posterior Abdominal Wall / Lumbar Plexus / Branches of Abdominal Aorta

Where does the right crus of the diaphragm originate from?

Upper 3 lumbar vertebrae

What does the right crus split to surround?

Esophagus

Weakness of the right crus may cause what?

Hiatal hernia

What does the left crus originate from?

Upper 2 lumbar vertebrae

What is the name for the thickening of fascia that connects the right crus to the left crus and forms the border of the aortic hiatus?

Median arcuate ligament

What does the medial arcuate ligament connect?

Body of first lumbar vertebra to TVP of 1st lumbar vertebra

What does the medial arcuate ligament pass over?

Psoas major muscle and sympathetic trunk

What does the lateral arcuate ligament connect?

TVP of 1st lumbar vertebra to 12th rib

What muscle does the lateral arcuate ligament pass over?

Quadratus lumborum

What is the function of the psoas major?

Flex thigh and trunk

What is the origin of the psoas minor muscle?

Bodies and IVDs of T12 and L1

What is the function of the psoas minor?

Flex trunk

What is the name of pain produced when the thigh is extended passively or patient flexes their leg?

Psoas sign

What does a positive right psoas sign indicate?

Acute appendicitis

In how many patients is the psoas minor present in?

60%

What muscle of the posterior abdominal wall is active in forced expiration and may be strained with excessive coughing?

Quadratus lumborum

What forms the lumbar plexus?

Anterior primary rami of L1, L2, L3, and part of L4

What nerve is sensory to the skin covering the pubis and gluteal region?

Iliohypogastric nerve

What rami form the iliohypogastric nerve?

L1

T/F: The ilioinguinal nerve accompanies the spermatic cord or round ligament of uterus through the inguinal cana.

True

What nerve supplies sensory innervation to the skin of scrotum or labia majora and the thigh?

Ilioinguinal nerve

What segmental innervation forms the ilioinguinal nerve?

L1

What are the two branches of the genitofemoral nerve?

Genital and femoral branches

What nerve supplies the cremaster muscle?

Genital branch of genitofemoral

What supplies the skin over the femoral triangle?

Femoral branch of genitofemoral

What is the segmental innervation of the genitofemoral nerve?

L1, L2

What nerve supplies the skin of the anterior and lateral aspects of the thigh?

Lateral cutaneous nerve of thigh

What is the segmental innervation of the lateral cutaneous nerve of the thigh?

L2, L3

What nerve supplies the muscles/skin of the medial surface of the thigh?

Obturator nerve

What is the segmental innervation of the obturator nerve?

L2, L3, L4

What nerve supplies the muscles and skin of the thigh?

Femoral nerve

What is the segmental innervation of the femoral nerve?

L2, L3, and L4

What anterior primary rami form the sacral plexus?

L4 through S4

Where does the abdominal aorta lie?

Midline

Where does the thoracic aorta lie?

Left side

Where does the inferior/superior vena cava lie?

Right side

What are the unpaired arteries from the abdominal aorta?

Celiac trunk

Superior mesenteric artery

Inferior mesenteric artery

Median sacral artery

Where does the abdominal aorta bifurcate?

Anterior to L4

What does the abdominal aorta bifurcate into?

R/L common iliac arteries

What do the common iliac arteries branch into?

Internal and external iliac artery