Posterior Abdominal Wall

Question 1

Quadratus Lumborum

• Attachments
• Function
• Innervation

Answer 1

• Iliac crest to 12th rib and L1-4 transverse processes
• One can bend the trunk to one side, and both together can force expiration and support the 12th rib
• T12-L4 anterior rami

Question 2

Iliacus

• Attachments
• Function
• Innervation

Answer 2

• Iliac fossa to join psoas as iliopsoas and insert into lesser trochanter of femus
• Hip flexion
• Femoral nerve

Question 3

Psoas

• Attachments
• Function
• Innervation

Answer 3

• T12-L4 bodies and intervertebral disks (superficially) and L1-L5 (deep) to join iliacus as iliopsoas. Attaches to lesser trochanter of femur.
• Flexes hip, can bend trunk laterally (one) or raise trunk from a supine position (both)
• Lumbar plexus direct branches (L2-4)

Question 4

Arcuate Ligaments

Answer 4

Question 5

Right and Left Crus

Answer 5

Question 6

Abdominal Aorta

• Entry into abdomen
• Branches
• Bifurcation

Answer 6

• @T12
• Diaphragm (inf. phrenic), abdominal wall (lumbar, median sacral), abdominal viscera, kidneys, ovaries/testes
• @L4 into common R&L common iliac to supply lower limb and pelvis

Question 7

Inferior Vena Cava

• Drains
• Formed by

Answer 7

• Body wall (lumbar, sacral), diaphragm (inferior phrenic), kidneys, supra-renal glands. Also blood from hepatic veins
• Two common iliac veins coming together @L5.

Question 8

Lumbar Veins

• 1&2 drain
• 3&4 drain
• 5 drains

Answer 8

• Into ascending lumbar
• Into IVC
• Into iliolumbar vein > common iliac

Question 9

Gonadal Vessels

• Arterial branches
• Veins

Answer 9

• Ovarian and testicular arteries direct from aorta @L2
• Ovarian and testicular veins drain directly to the IVC on the right, and to the left renal on the left

Question 10

Posterior Abdominal Wall Lymphatics

• Iliac nodes
• Para-aortic (lateral) nodes
• Pre-aortic nodes
• Cisterna chyli

Answer 10

• Lymph from pelvis
• Lymph from the body wall, kidneys, testes and ovaries
• Lymph from digestive tract - coeliac, inferior and superior mesenteric
• L1,L2 - start of thoracic duct.

Question 11

Lumbar Plexus

• Root value
• Branches
• Nerves of the plexus

Answer 11

• Anterior rami L1-L4
• Form within psoas. Some sensory to pelvic skin but most to lower limb
• As shown

Question 12

Iliohypogastric and ilioinguinal nerves

• Root value
• Iliohypogastric
• Ilioinguinal

Answer 12

• Anterior ramus L1
• Sensory to lateral gluteal skin and pubic skin. Motor to internal oblique and transversus abdominis
• Sensory to skin on medial thigh and root penis/scrotum or mons pubis/labium majus. Motor to internal oblique and transversus abdominis

Question 13

Genitofemoral Nerve

• Root Value
• Provides
• Branches

Answer 13

• Anterior Rami L1, L2
• Sensory innervation to scrotum/mons pubis and skin of upper anterior thigh. Motor to cremasteric muscle.
• Genital and femoral branches

Question 14

Lateral Cutaneous Nerve

• Root value
• Provides

Answer 14

• Anterior rami L2, L3
• Sensory innervation to the skin on the anterior and lateral thigh

Question 15

Femoral Nerve

• Root value
• Sensory
• Motor

Answer 15

• L2-L4
• To skin on anterior thigh and medial leg
• To pectineus, iliacus and anterior compartment of thigh

Question 16

Obturator Nerve

• Root value
• Sensory
• Motor

Answer 16

• Anterior rami L2-L4
• To skin on medial thigh
• To obturator externus and medial compartment of thigh