Lumbar Plexus

Lumbar plexus formed by

ventral primary rami (VPR) of L1-L4 (with minor T12 contribution)

Differentiate anterior/posterior rootlets, ventral/dorsal rami, anterior/posterior divisions, and anterior/posterior branches

anterior/posterior rootlets - branches off of spinal cord that merge to form spinal nerve

ventral/dorsal rami - branches from a spinal nerve

anterior/posterior divisions - branching of the ventral rami, not every rami has these divisions

anterior/posterior branches - divisions in a peripheral nerve

Iliohypogastric nerve segmental innervation

L1 VPR

Iliohypogastric nerve branches

muscular branches (partial innervation to transverse abdominis and internal abdominal oblique muscles) and cutaneous branches (posteriolateral gluteal region + abdomen above pubis)

Iliohypogastric muscular branches

partial innervation to transverse abdominis and internal abdominal oblique muscles

Iliohypogastric cutaneous branches

posteriolateral gluteal region + abdomen above pubis

Ilioinguinal nerve segmental innervation

L1 VPR

Ilioinguinal characteristic

smaller/thinner than iliohypogastric

Ilioinguinal branches

muscular branches (partial innervation to internal abdominal oblique muscles) and cutaneous branches (superomedial thigh + skin over genitals)

Ilioinguinal muscular branches

partial innervation to internal abdominal oblique muscles

Ilioinguinal cutaneous branches

superomedial thigh + skin over genitals

Genitofemoral segmental innervation

L1, L2 VPR

Genitofemoral characteristic

pierces psoas major

Genitofemoral branches

genital branch (motor supply to cremaster muscle) and femoral branch (cutaneous supply to skin over femoral triangle)

Genitofemoral muscular branch

genital branch, motor supply to cremaster muscle

Genitofemoral cutaneous branch

femoral branch, cutaneous supply to skin over femoral triangle

Obturator nerve segmental innervation

anterior division of L2, L3, L4 VPR

Obturator nerve characteristics

divides into anterior and posterior branches near obturator canal

Obturator nerve branches

anterior and posterior branches

Obturator nerve anterior branch parts + characteristic

hip joint, femoral artery, motor supply to adductor longus, gracilis, and adductor brevis, cutaneous supply to medial thigh; exits above obturator externus

Obturator nerve posterior branch parts + characteristic

motor supply to obturator externus and obturator magnus, articular branch to knee joint; pierces obturator externus

Accessory obturator nerve segmental innervation

anterior division of L3, L4 VPR

Accessory obturator nerve characteristics

only in 10% of people, runs anterior to obturator nerve

Accessory obturator branches

articular branch (hip joint), motor supply to pectineus

Femoral nerve segmental innervation

posterior division of L2, L3, L4 VPR

Femoral nerve characteristics

superficial, between iliacus and psoas major, lateral most structure in femoral triangle

Femoral nerve branches

muscular branch (iliacus, sartorius, pectineus, quadriceps femoris (all 4)), cutaneous branch (with both anterior cutaneous branch and saphenous nerve), articular branch to knee, and vascular branch to femoral triangle

Femoral nerve muscular branch

iliacus, sartorius, pectineus, quadriceps femoris (all 4)

Femoral nerve cutaneous branch

divides into anterior cutaneous branch (L2, L3) supplying anterior thigh and saphenous nerve (L3, L4) supplying skin of medial patella, leg, and foot

Anterior cutaneous branch segmental innervation and what it supplies

L2, L3 (from femoral nerve so posterior division of VPR), supplies anterior thigh

Saphenous nerve segmental innervation and what it supplies

L3, L4 (from femoral nerve so posterior division of VPR), supplies skin of medial patella, leg, and foot

Femoral nerve articular branch

to knee

Femoral nerve vascular branch

to femoral triangle

Lateral femoral cutaneous nerve segmental innervation

posterior division of L2, L3 VPR

Lateral femoral cutaneous nerve characteristics

runs under inguinal ligament and lateral to femoral triangle, if it becomes entrapped under inguinal ligament, causes burning and numbness in region of its cutaneous supply, called Meralgia Paresthetica

What lateral femoral cutaneous nerve supplies

anterolateral thigh

Femoral triangle superior border

inguinal ligament

Femoral triangle medial border

adductor longus

Femoral triangle lateral border

sartorius

Femoral triangle contents lateral to medial

NAVEL, femoral nerve, femoral artery, femoral vein, empty space, lymph nodes

Femoral triangle floor

iliopsoas and pectineus

Femoral triangle roof

fascia lata