Lumbosacral Plexus

Question 1

List the nervous system components from the spinal nerve to the peripheral nerves?

Answer 1

• spinal nerve
• make a ventral rami
• which makes a plexus
• separate to form peripheral nerve

Question 2

What spinal nerves form the iliohypogastric nerve? What does it supply/cutaneous innervations?

Answer 2

• T12 to L1
• runs along iliac crest, superior to inguinal canal
• lateral superior thigh and superior inguinal region

Question 3

What spinal nerves form the ilioinguinal nerve? Where does it run? What does it supply/cutaneous innervations?

Answer 3

• L1
• runs along iliac crest, then within inguinal canal
• symphysis, superior medial thigh, scrotum/labia majora

Question 4

What spinal nerves form the genitofemoral nerve? What muscle does it pierce?Where does the branches runs? What does it supply/cutaneous innervations?

Answer 4

• L1-L2
• pierces the psoas major
• genital branch runs within the inguinal canal
• femoral branch pierces fascia lata below inguinal canal
• genital branch supplies scrotum, labia major, cremaster muscle
• femoral branch supplies the anterior medial superior thigh

Question 5

What spinal nerves form the lateral femoral cutaneous nerve? Where does it run? What does it supply/cutaneous innervations?

Answer 5

• L2-L3
• runs along iliacus, then pierces fascia lata
• supplies anterior superior thigh

Question 6

What spinal nerves form the femoral nerve? What are the muscular branches? What does it supply?

Answer 6

• L2-L4
• quads, iliacus, sartorius, pectineus
• anterior thigh and then medial leg when it becomes the saphenous L4 nerve

Question 7

What spinal nerves form the obturator nerve? Where does it run? What are the muscular branches? What are the articular branches? What are the cutaneous branches?

Answer 7

• L2-L4
• runs w/ the obturator artery
• muscles: obturator externus, adductor long/magnus/brevis, gracilis, pectineus
• articulations: hip (ligaments and fibrous joint capsule)
• cutaneous: distal medial thigh

Question 8

What spinal nerves form the superior gluteal nerve? What muscles does it supply?

Answer 8

• L4 - S1

- TFL, gluteus medius, gluteus minimus

Question 9

What spinal nerves form the inferior gluteal nerve? What muscles does it supply?

Answer 9

• L5-S2

- gluteus maximus

Question 10

What spinal nerves form the sciatic nerve? What are the two main branches?

Answer 10

• L4-S3
• Tibial
• Common fibular

Question 11

What are the nerve branches of the tibial nerve? And its muscular branches?

Answer 11

Nerve: medial plantar, lateral plantar, medial sural, and medial calcaneal
Muscular: hamstrings, adductor magnus posterior, gastrocnemius, soleus, plantaris, popliteus, flexor hallicus longus, flexor digitoum longus, tibialis posterior

Question 12

What are the nerve branches of the common fibular and what do they innervate?

Answer 12

Superior fibular: cutaneous- anterior ankle, dorsum
-muscular: fibularis longus and brevis
Deep fibular: muscular- tibialis anterior, extensor digitorum longus, extensor digitorum brevis, extensor hallicus longus, extensor hallicus brevis, fibularis tertius
Lateral sural

Question 13

What are the nerve branches and cutaneous innervations of the posterior femoral cutaneous nerve?

Answer 13

• cutaneous innervations: posterior thigh

- nerve branches: inferior cluneal branch

Question 14

What are the muscular innervations of the plantar nerve?

Answer 14

• medial: abductor hallicus, flexor digitor brevis, flexor hallicus brevis, 1st lumbrical
• lateral: adductor hallicus, quadratus plantae, abductor digiti minimi, 2-4 lumbricals, all interossei, FDMB, and FHB lateral head