📝 STANDARD DESCRIPTION:
FEMORAL NERVE (L4-L6):
- Exits abdomen between psoas muscles into femoral triangle on medial thigh.
- Supplies: iliopsoas + QUADRICEPS FEMORIS (extensor of stifle).
- Sensory: medial side of thigh and leg (via saphenous nerve).
- Damage → cannot extend stifle → leg buckles → 'dropped haunch'.
OBTURATOR NERVE (L4-L6):
- Runs along medial wall of pelvis on shaft of ilium.
- Exits through obturator foramen.
- Supplies: ADDUCTORS of thigh.
- Damage during difficult calving → adductors paralyse → cow's hind legs splay sideways = 'Calving Paralysis / Downer Cow'.
📚 DETAILED DESCRIPTION:
FEMORAL & OBTURATOR NERVES
FEMORAL NERVE:
Origin: Lumbar plexus (L4-L6).
Course: Runs through the substance of the iliopsoas, exits the abdomen on the medial side of the thigh in the femoral triangle with the femoral artery.
Supplies:
• Motor — iliopsoas, sartorius, the quadriceps femoris (the main stifle extensor).
• Sensory — terminates as saphenous nerve for skin of medial thigh, leg, and hock.
Clinical importance: If this nerve is damaged (calving paralysis, hip injury, prolonged dorsal recumbency on a hard table), the quadriceps cannot fire → the stifle CANNOT extend → the limb buckles forward when the animal tries to bear weight ('dropped quarter' in calves).
OBTURATOR NERVE:
Origin: Lumbar plexus (L4-L6).
Course: The nerve descends along the medial side of the shaft of ilium, then crosses the floor of the bony pelvis directly above the obturator foramen, and finally exits via that foramen onto the medial thigh.
Supplies: All the adductor muscles of the thigh — pectineus, gracilis, adductor, obturator externus.
CALVING PARALYSIS — IMPORTANT UG TOPIC:
During difficult calving, the calf's body crushes the obturator nerve against the pelvic floor. After parturition, the cow tries to stand but the adductors fail → both hind legs slide outward to either side ('splay leg' / 'do the splits') → cow falls = downer cow.
Treatment: Apply HOBBLES above hocks to keep legs together until nerve recovers; soft bedding; lift cow regularly. May take days-weeks to recover.
// COMPARATIVE ANALYSIS
| CATTLE |
Most commonly affected by calving paralysis (obturator). |
| DOG |
Femoral nerve injury (rare) → quadriceps paralysis after iliopsoas injury. |
CLINICAL RELEVANCE
Calving Paralysis (Downer Cow): Bilateral obturator nerve damage during dystocia. Hobbles + soft bedding are key.
Femoral Pulse: Felt in the femoral triangle medial to thigh in DOG — used to check pulse and to do femoral venipuncture.
