Lumbar Plexus Flashcards
what is the lumbar plexus formed from?
anterior rami (division from spinal cord) of L1-L4, receiving some contribution from T12
where is the lumbar plexus found?
anterior to the transverse process of the lumbar vertebrae and within the psoas major region
what makes up the lumbar plexus?
the anterior rami of L1-L4 from lumbar spinal nerves leaving via intervertebral foramina makes up the lumbar plexus
What forms the cords of the lumbar plexus?
the anterior rami of L1-L4 combine together to form the 6 major peripheral nerves of the lumbar plexus
where do the lumbar cords travel to innervate their target structures?
posterior abdominal wall to reach the lower limb, there innervating target structures
Name the 6 branches of the lumbar plexus
- Iliohypogastric nerve
- ilioinguinal nerve
- genitofemoral nerve
- lateral femoral cutaneous nerve
- femoral
- obturtor
Iliohypogastric nerve
1st major branch of lumbar plexus, innervate anterior abdominal wall
Roots: T12 + L1
Motor: internal oblique + transversus abdominis (directly below internal oblique in the abdomen area)
Sensory: posterolateral gluteal skin in the pubic region
Ilioinguinal nerve
pass through superficial inguinal ring to innervate skin of genitalia
Roots: L1
Motor: internal obliquie + transversus abdominis
Sensory: skin of upper middle thigh, root of penis + anterior scrotum (males), mons pubis + labrium majus (females)
Genitofemoral nerve
divide into genital branch after leaving psoas major muscles
Roots: L1, L2
Motor: Genital branch innervates cremasteric muscle
Sensory: genital branch innervates skin of anterior scrotum (males), mons pubis and labium majus (females), femoral branch innervates skin of upper anterior thigh
lateral cutaneous nerve of the thigh
purely sensory nerve (cutaneous)
Roots: L2 + L3
Sensory: anterior + lateral thigh down to level of knee
Obturator Nerve
Roots: L2, L3, L4
Motor: obturator externus, pectineus, adductor longus, adductor brevis, adductor magnus, gracilis
Sensory: skin over medial thigh
Femoral nerve
Roots: L2, L3, L4
Motor: iliacus, pectineus, sartorius, muscles of quadriceps femoris
Sensory: skin on anterior thigh and medial leg
Memory aid for lumbar plexus
I, I Get Leftovers On Friday
Iliophypogastric, Ilioinguinal, Genitofemoral, Lateral cutaneous, Oturator, Femoral
Lumbosacral plexopathy
rare, damage to nerve bundles (lower/end) of lumbar / sacral plexus
neuropathic pains (abnormal nervous sensation), numbness, weakness, atrophy (wasting of muscles)
Main cause: diabetic amyotrophy (muscular atrophy)
what are the causes of lumbosacral plexopathy?
- diabetic amyotrophy - high blood sugar damage nerves
- idiopathic plexopathy - acute inflammation of the plexus
- compression of plexus due to tumours / other local invasions (can cause pain and loss of motor control)
