Lumbosacral Plexus

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The lumbosacral plexus can be divided into two anatomical parts: the upper lumbar plexus and the lower lumbosacral plexus.

Lumbar Plexus

The lumbar plexus is located within the psoas muscle. It contains the canterior rami of the T12 to L4 nerve roots. Only the femoral nerve can be reliably tested by EMG. The lateral femoral cutaneous nerve can be tested but it is unreliable.

Lumbar Plexus

Nerve	Segment	Motor Supply	Action	Sensory Supply
Iliohypogastric nerve	T12/L1	Transversus abdominis and internal oblique muscles	N/A	Lower abdomen
Ilioinguinal nerve	L1	Inferior abdominal muscles	N/A	Inguinal region, small area of media thigh, and upper scrotum/labia
Genitofemoral nerve	L1, L2	Cremasteric muscle in men	N/A	Skin of femoral triangle. Lower scrotum/labia
Lateral femoral cutaneous nerve	L2,L3	N/A	N/A	Lateral thigh
Obturator nerve	L2, L3, L4 anterior rami	Adductor magnus (anterior half), adductor longus, adductor brevis, gracilis, obturator externus	Hip adduction	Medial thigh
Femoral nerve	L2, L3, L4 anterior rami, posterior divisions	Quadriceps femoris, sartorius, pectineus, iliacus	Knee extension	Medial lower leg (through saphenous nerve
Lumbosacral trunk / furcal nerve	L4-5, mainly L5		Ankle dorsiflexion, eversion, inversion	L5 sensory loss

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  Lumbar Plexus

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  Subcostal nerve

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  Iliohypogastric nerve

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  Ilioinguinal nerve

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  Genitofemoral nerve

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  Lateral femoral cutaneous nerve

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  Obturator nerve

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  Femoral nerve

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  Lumbosacral trunk

Sacral Plexus

The sacral plexus is derived from the anterior rami of spinal nerves L4-S4 forming the lumbosacral trunk.

Sacral Plexus

Nerve	Segment	Motor Supply	Action	Sensory Supply
Superior gluteal	L4-S1	Gluteus medius, gluteus minimus, tensor fasciae latae	hip abduction	buttock pain
Inferior gluteal	L5-S2	Gluteus maximus	hip external rotation and power extension	N/A
Sciatic trunk/nerve	L5–S3	Tibial portion: Posterior compartment of the thigh and leg Common peroneal division: short head of biceps femoris, and anterior, and lateral compartments of the leg, and extensor digitorum brevis. and leg through common peroneal and tibial nerves		Tibial portion: Sole of the foot (medial and lateral plantar nerves) Common peroneal division: Anterolateral surface of the leg (sural nerve), first webspace of foot (deep peroneal nerve), and dorsal aspect of the foot (superficial peroneal nerve)
Posterior femoral cutaneous nerve		-	-	Posterior surface of the thigh, leg, and perineum (perineal branches and inferior cluneal nerves)
Pudendal nerve	S2-4	Muscles of the perineum		Penis, clitoris, most of the perineum
Nerve to piriformis
Nerve to obturator internus and superior gemellus

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  Sacral Plexus

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  Superior gluteal nerve

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  Inferior gluteal nerve

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  Nerve to piriformis

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  Sciatic nerve

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  Nerve to quadratus and inferior glemellus

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  Nerve to obturator internus and superior gemellus

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  Posterior femoral cutaneous nerve

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  Perforating cutaneous nerve

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  Pudendal nerve

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  Nerves to perineum and levator ani

Other Branches

Nerve	Segment	Motor Supply	Action	Sensory Supply
Tibial	L4-S3	Hamstrings (except short head of biceps femoris, posterior part of adductor magnus), triceps surae, tibialis posterior, popliteus, flexor digitorum longus, flexor hallucis longus, intrinsic muscles of foot	Knee flexion(primary), foot plantar flexion, toe flexion	skin of posterior leg and sole of foot
Common fibular	L4-S2	short head of biceps femoris, fibularis longus and brevis, tibialis anterior, extensor hallucis	knee flexion (short head of biceps femoris), foot dorsiflexion and eversion, toe extension	skin of anterior and lateral leg and dorsum of foot

Additional Images

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  Lumbar Plexus