Nerves of the Pelvic and Gluteal Region

Question 1

Lumbar plexus

Answer 1

• Anterior primary rami L1-L3, part of L4, some T12

* Located posterior to/in psoas major

Question 2

T12 and L1 form…

Answer 2

• Iliohypogastric (T12, L1)
• Ilioinguinal (L1)
• Genitofemoral (L1, L2)

Question 3

Iliohypogastric nerve

Answer 3

Iliohypogastric (T12/L1)
• Cranial end of lateral psoas major
• Crosses quadratus lumborum, passes iliac crest, enters intneral surface of transversus abdominis & internal oblique
• Lateral cutaneous branches – posterior gluteal area
• Anterior cutaneous branches – hypogastric region
• Muscle branches: transversus abdominis & internal oblique

Question 4

Ilioinguinal nerve

Answer 4

Ilioinguinal (L1)
• Lateral border psoas major
• Caudal to iliohypogastric
• Parallel w/ iliohypogastric across quadratus lumborum to iliac crest, pierces trasnversus abdominis
• Communication w/ iliohypogastric: between transversus abdominis and internal oblique
• With sperm cord through superifical inguinal ring
• To medial thigh, root of penis, anterior scrotum

Question 5

Genitofemoral nerve

Answer 5

Genitofemoral (L1, L2)
• Passes through psoas major to ventral surface
• Genital branch: joins spermatic cord and round ligament to supply lateral scrotum and adjacent thigh
• Femoral branch runs lateral to genital branch and deep to inguinal ligament in lateral femoral sheath to supply skin over anterior thigh

Question 6

L2, L3 and L4

Answer 6

Split into anterior and posterior divisions

Question 7

Anterior divisions of L2, L3 and L4

Answer 7

Obturator (L2,3,4)
• medial to psoas major
• enters pelvis under iliac vessels
• exitsthrough obturator canal

Accessory obturator (L3,L4)
• Present 10%
• Runs medial to psoas major m.
• Leaves pelvis by passing superior to pubic ramus
• Deep to pectineus in thigh, becomes a muscular branch
• May give off articular branch to hip

Question 8

Posterior divisions of L2, L3 and L4

Answer 8

Femoral (L2,3,4)
• Travels through psoas major
• Distally, runs between psoas major and iliacus
• Leaves pelvis deep to inguinal ligament, lateral to femoral artery

Lateral femoral cutaneous (L2,L3) 
•	Middle/lateral border psoas major
•	Over iliacus
•	To ASIS 
•	Inferior inguinal ligament
•	Over Sartorius 
•	Anterior branch- skin over lateral/anterior thigh
•	Posterior branch – skin lateral thigh from greater trochanter distally to mid-thigh

Question 9

Variations

Answer 9

1. Iliohypogastric/ilioinguinal nerves can come from common trunk
2. Ilioinguinal nerve is absent with genitofermoral taking over innervation
3. Cutaneous branches of femoral nerve are variable

Question 10

Sacral plexus

Answer 10

• Lumbosacral trunk: pats L4, L5-S3, part S4
• Medial to piriformis
• Converge at greater sciatic foramen
• All branches EXCEPT S4 branch into anterior/posterior divisions

***L4= Nervus furcalis > divided into two plexuses

Question 11

Anterior division

Answer 11

Nerve to quadratus femoris/inferior gemellus (L4-S1)

• Greater sciatic foramen, ventral to sciatic n
• Articular branch to hip joint

Nerve to obturator internus/superior gemellus (L5-S2)

• greater sciatic foramen
• Reenters through lesser sciatic foramen to bturator internus

Question 12

Posterior division

Answer 12

Nerve to piriformis (S2 or S1/S2)

Superior gluteal (L4-S1)

• Greater sciatic foramen superior to piriformis
• Superior branch to gluteus minimus
• Inferior branch to gluteus medius/minimus, tensor fascia latae

Inferior gluteal (L5-S2)

• Greater sciatic foramen
• Inferior piriformis
• Supplies gluteus maximus

Question 13

Sciatic nerve

Answer 13

o Largest nerve in body, largest branch sacral plexus
o Anterior division: L4-S3
o Posterior divison L4-S2
o Supplies: posterior leg muscles, all muscles of the leg, foot, skin foot most skin leg, all joints in lower extrmity
o Greater sciatic formina inferior to piriformis
o Cranial end: rests posterior ischium btwn ischial tuberosity & greater trochanter of femur
o Crosses obturator internus tendon, gemelli m, quadratus femoris
o Accompanied by posterior femoral cutaneous and inferior gluteal artery
o Articular branches to hip joint
o One antaomic nerve

Question 14

Sciatic nerve - two physiologic nerves

Answer 14

Two physiologic nerves in one connective sheath

• Tibial (anterior L4-S3)
• Common peroneal (posterior L4-S2)

Question 15

Posterior femoral cutaneous nerve of sacral plexus

Answer 15

Posterior femoral cutaneous (S2, S3A, S1/S2P)
o Skin gluteal region, posterior thigh, perineum, upper leg
o Gluteal branches: Inferior cluneal – lateral to gluteus maximus

Question 16

Perineal branches of sacral plexus

Answer 16

o Medial to proximal thigh, perineum, scortum, base penis/labia majora

Question 17

Femoral branches of sacral plexus

Answer 17

o Skin posterior/medial thigh and popliteal fossa

Question 18

Sural branches of sacral plexus

Answer 18

o Skin distal popliteal fossa

Question 19

Coccygeal plexus

Answer 19

• Part S4, S5, coccygeal anterior rami