Lumbar Plexus

Question 1

Iliohypogastric nerve

Answer 1

Courses along (superior border of) iliac crest

Roots: L1 (+ Recieve contributions from T12)

Motor innervation:

1) Internal oblique muscle
2) Transversus abdominis muscle

Sensory innervation:
1) Posterolateral gluteal skin over pubic region

Question 2

Ilioinguinal nerve

Answer 2

Courses along iliac crest

Roots: L1

Motor innervation:

1) Internal oblique muscle
2) Transversus abdominis muscle

Sensory innervation:

1) Males – skin over root of penis and anterior scrotum
2) Females – skin over mons pubis and labia major
3) Skin superior antero-medial thigh

Question 3

Lateral cutaneous nerve

Answer 3

Courses anterior to iliacus muscle and passes deep to inguinal ligament

Roots: L2-L3

Sensory innervation:
1) Skin of anterior and lateral aspects of thigh (till the knee)

Question 4

Femoral nerve

Answer 4

Arises from lateral border of Psoas major muscle and passes deep to inguinal ligament

Roots: L2-L4

Motor innervation:
1) Muscles of anterior compartment of thigh (pectineus, sartorius, quadriceps femoris, iliacus)

Sensory innervation:
1) Skin of anterior thigh and medial leg

Question 5

Genitofemoral nerve

Answer 5

Courses on the ANTERIOR surface of Psoas major muscle and divides into the genital and femoral branches after leaving the psoas major muscle
It also transverse the inguinal canal along with spermatic cord (male) or round ligament (female)

Roots: L1 - L2

Motor innervation:
1) Cremaster muscle (males)

Sensory innervation:

1) Males – skin of anterior scrotum
2) Females – skin over mons pubis and labia major
3) Upper anterior thigh (femoral branch)

Question 6

Obturator nerve

Answer 6

Arises from the MEDIAL border of psoas major muscle and transverse the obturator foramen

Roots: L2-L4

Motor innervation:
1) Muscles of medial compartment of thigh (gracilis, adductor magnus, adductor brevis, adductor longus, obturator externus)

Sensory innervation:
1) Skin over medial aspect of thigh