Overview

Relationship to Psoas
- Three lateral
- Two through
  - Genitofemoral Nerve
  - Femoral nerve
- Two medial
  - Obturator Nerve
  - Lumbosacral trunk
Formed from anterior rami of the upper 4 lumbar nerves after they have supplied Psoas Major and Quadratus Lumborum segmentally
Formed in the substance of the Psoas Major
Supplies part of the lower abdo wall but mainly concerned in supplying skin and muscle in the lower limb
Reinforces Sacral Plexus – the true plexus of the lower limb

Branches

Are really just the 1st lumbar segmental body-wall nerve and its collateral branch
Supplies: Skin overlying inguinal region, front of scrotum, motor supply for fibres of Internal Oblique and Transversus that forms the roof of the inguinal canal and reach the conjoint tendon

Femoral Part: Area of skin below middle of Inguinal Ligament
Genital Part: Spermatic Cord – Sensory to Tunica Vaginalis, Spermatic Fascia and small area of anterior scrotal and labial skin, and motor to Cremaster

Entirely sensory
Supplies: Iliac Fascia, Peritoneum of Iliac Fossa, lateral side of thigh down to knee
Emerges from lateral border of Psoas
Enters thigh by passing through or under lateral part of Inguinal Ligament

Issues from the lateral border of Psoas
Crosses the iliac fossa in the gutter between Psoas and Iliacus, deep to Iliac Fascia
Supplies:
- Iliacus in abdo
- Anterior thigh muscles
  - Nerve to Pectineus – runs behind Femoral Sheath to reach muscle
  - Nerves to Sartorius – One often pierces the muscle and continues on as an Intermediate Femoral Cutaneous Nerve – supplies skin and fascia lata over front of thigh down to knee
  - Nerve to Rectus Femoris – upper branch also supplies hip joint
  - Nerve to Vastus Lateralis runs down with the descending branch of Lateral Femoral Circumflex Artery between Rectus Femoris and Vastus Intermedius
  - Nerve to Vastus Intermedius – Sinks into the anterior muscle surface
  - Nerve to Vastus Medialis – Enters upper part of Subsartorial Canal and sinks into muscle
  - Nerves to all three vasti also supply Knee Joint
- Cutaneous
  - Medial Femoral Cutaneous Nerve – supplies medial side of thigh
  - Anterior branch – reaches front of the knee
Saphenous nerve:
- Crosses in front of Femoral Artery in Subsartorial Canal
- Emerges behind the posterior border of Sartorius
- Infrapatellar Branch – pierces Sartorius to run into Patellar Plexus
- Pierces the Fascia Lata between the tendons of Sartorius and Gracilis
- Descend to supply skin and periosteum over subcutaneous surface of Tibia
- Runs with the Great Saphenous Vein in front of the Medial Malleolus
- Ends on the medial side of the foot just short of the big toe

Emerges from Medial Side of Psoas
Lies on the Ala of the Sacrum lateral to the Lumbosacral trunk
Slants down to side wall of pelvis between origin of Internal Iliac Artery and Ilium
From the angle between External and Internal Iliac Vessels, it runs straight to the Obturator Foramen
Supplies Parietal Peritoneum of side wall of pelvis
As it emerges from Obturator Foramen, it splits into anterior and posterior divisions
Posterior Division supplies:
- Obturator Externus
- Pubic portion of Adductor Magnus
- Knee joint via branch accompanying Femoral Artery into Popliteal Fossa
Anterior Division supplies:
- Hip Joint
- Adductor Brevis
- Adductor Longus
- Maybe Pectineus
- Gracilis
- Medial side of the thigh by a cutaneous branch
Accessory Obturator Nerve, when occasionally present, passes over Superior Pubic Ramus to supply Pectineus

L4 and L5
These roots descend medially across the pelvic brim, over the ala of the sacrum, to join the sacral plexus (S1–S4)