1. LUMBOSACRAL PLEXUS
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3. Lumbar plexus (T12- L4):
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4. Lumbar Plexus L2—L4. Largest branch of lumbar plexus.
Femoral nerve:
L2—L4.
Largest branch of lumbar plexus.
Emerges from lateral side of psoas major.
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5. Lumbar Plexus Enters thigh behind inguinal ligament. Supplies:
Femoral nerve:
Enters thigh behind inguinal ligament.
Supplies:
In iliac fossa:
Iliacus (GSE); pectineus (GSE); femoral artery (GVE).
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6. Lumbar Plexus Supplies: Terminates as: Distally:
Femoral nerve:
Supplies:
Distally:
Sartorius; quadriceps femoris; anterior thigh (GSA).
Terminates as:
Saphenous nerve (GSA) to medial thigh and foot.
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7. Lumbar Plexus L2..L4. Emerges from medial side of psoas major.
Obturator nerve:
L2..L4.
Emerges from medial side of psoas major.
Descends along lateral wall of pelvis.
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8. Lumbar Plexus Enters thigh through obturator foramen:
Obturator nerve:
Enters thigh through obturator foramen:
In obturator groove it divides into:
Anterior branch (anterior to adductor brevis).
Posterior branch (posterior to adductor brevis).
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9. Lumbar Plexus Supplies: Medial thigh muscles (GSE).
Obturator nerve:
Supplies:
Medial thigh muscles (GSE).
Skin on medial thigh (GSA).
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10. Sacral Plexus
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12. Sacral Plexus Passes through greater sciatic notch above piriformis.
Superior gluteal nerve:
L4..S1.
Passes through greater sciatic notch above piriformis.
Supplies lateral gluteal compartment.
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13. Sacral Plexus Passes through greater sciatic notch below piriformis.
Inferior gluteal nerve:
L5..S2.
Passes through greater sciatic notch below piriformis.
Supplies posterior gluteal compartment.
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14. Sacral Plexus Runs with gluteal nerves deep to gluteus maximus.
Posterior femoral cutaneous:
Runs with gluteal nerves deep to gluteus maximus.
Then runs with sciatic nerve and gluteal artery.
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15. Sacral Plexus Supplies:
Posterior femoral cutaneous:
Supplies:
Skin on buttock (GSA) via inferior cluneal nerve.
Skin of external genitalia (GSA) via perineal branches.
Skin on back of thigh.
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16. Sacral Plexus L4..S1. To quadratus femoris (GSE): To piriformis (GSE):
Nerves to lateral thigh compartment:
To inferior gemellus (GSE):
L4..S1.
To quadratus femoris (GSE):
To piriformis (GSE):
S1..S2.
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17. Sacral Plexus Common peroneal (fibular). Tibial.
Sciatic nerve:
Fusion of:
Common peroneal (fibular).
Tibial.
Largest physical nerve in the body.
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18. Sacral Plexus Exits pelvis through greater sciatic foramen:
Sciatic nerve:
Exits pelvis through greater sciatic foramen:
Inferior to piriformis (usually).
Descends between gluteus maximus.
Between greater trochanter and ischial tuberosity.
Lies on:
Ischium, gemelli, obturator internus, quadratus femoris.
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19. Nerve Injuries Total muscle function is lost.
Peripheral:
All motor function and sensation supplied by nerve distal to injury is lost.
Total muscle function is lost.
Sensation over more than one dermatome is lost.
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20. Nerve Injuries Sensory impairment over one dermatome.
Nerve root:
Usually affected by disc herniation immediately cranial (superior) to it.
Sensory impairment over one dermatome.
Muscle weakening.
May only affect one root or the other.
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22. Lumbar Plexus Femoral nerve Obturator nerve Lateral femoral cutaneous
Cutaneous branches
Thigh, leg, foot (e.g. saphenous nerve)
Motor branches
Anterior thigh muscles (e.g. quadriceps, sartorius, iliopsoas)
Obturator nerve
Sensory
Skin medial thigh; hip, knee joints
Motor
Adductor muscles
Lateral femoral cutaneous
Skin lateral thigh
Genitofemoral
Skin scrotum, labia major, anterior thigh
Cremaster muscle
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23. Sacral plexus (L4-S4) Sciatic nerve (L4-S3) Tibial nerve
Motor to muscles of pelvis and lower extremity (gluteal, posterior femoral, lower leg & foot)
Sensory from posterior pelvis, posterior thigh, anterior, posterior & lateral leg
Sciatic nerve (L4-S3)
Tibial nerve
Common peroneal (fibular) nerve
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26. Anterior compartment- Extensors of the knee Femoral Nerve
lateral
medial
femur
Medial compartment-
Adductors of the knee
Obturator Nerve
Posterior compartment-
Flexors of the knee
Sciatic Nerve
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27. Motor Branches of the Femoral Nerve L2 L3 L4 Rectus femoris iliopsoas
pectineus
sartorius
Vastus lateralis
Vastus medialis
Vastus intermedius
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28. Motor Branches of the Obturator Nerve Adductor brevis Adductor longus
gracilis
Adductus magnus
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29. Motor Branches of the Sciatic Nerve Hamstrings Common peroneal nerve
Semitendinosis
Biceps femoris
semimembranosus
Hamstrings
Common peroneal nerve
Tibial nerve
Deep peroneal nerve
Superficial peroneal nerve
Anterior compartment of leg
Gastrocnemius and posterior compartment of the leg and foot
Lateral compartment of leg
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30. Dermatomes (innervation of skin)
(area of skin innervated by the cutaneous branches from a single spinal nerve is called a dermatome)
Reveal sites of
damage to spinal
nerves or spinal cord
Dermatomes (innervation of skin)
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