Lumbosacral Plexus

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A: ventral aspect of the lumbar plexus. B: dorsal aspect of the sacral plexus. See abbreviations
Lumbosacral Plexus
Nerve Type	Plexus
Origin	Lumbar Plexus: T12-L4 Sacral Plexus: L4-S4
Major Branches	Lumbar Plexus: Femoral Nerve, Genitofemoral Nerve, Iliohypogastric Nerve, Ilioinguinal Nerve, Lateral Femoral Cutaneous Nerve, Lumbosacral Trunk, Obturator Nerve, Tibial Nerve and Common Peroneal Nerve (through sciatic trunk) Sacral Plexus: Inferior Gluteal Nerve, Nerve to Obturator Internus and Superior Gemellus, Nerve to Quadratus Femoris and Inferior Gemellus, Nerve to Piriformis, Posterior Femoral Cutaneous Nerve, Pudendal Nerve, Sciatic Nerve, Superior Gluteal Nerve, Perforating Cutaneous Nerve

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.

Nerve	Origin	Sensory Innervation	Motor Innervation
Femoral Nerve	L2, L3, L4 anterior rami, posterior divisions	Skin of medial lower leg through Saphenous Nerve	Quadriceps Femoris, Sartorius, Pectineus, Iliacus,
Genitofemoral Nerve	L1, L2	Skin of femoral triangle, lower scrotum/labia	Cremasteric muscle in men
Iliohypogastric Nerve	T12, L1	Skin of lower abdomen	Transversus Abdominis, Internal Obliques
Ilioinguinal Nerve	L1	Skin to inguinal region, small area of medial thigh, upper scrotum/labia.	Transversus Abdominis, Internal Oblique
Lateral Femoral Cutaneous Nerve	Posterior divisions of L2 and L3 spinal nerves	Anterolateral thigh
Lumbosacral Trunk	L4, L5 (mainly L5)	Skin of L5	Ankle dorsiflexors, ankle everters, ankle inverters
Obturator Nerve	L2, L3, L4 anterior rami	Skin of medial thigh	Adductor Magnus (anterior half), Adductor Longus, Adductor Brevis, Gracilis, Obturator Externus

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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.

Nerve	Origin	Sensory Innervation	Motor Innervation
Inferior Gluteal Nerve	L5, S1, S2		Gluteus Maximus
Nerve to Obturator Internus and Superior Gemellus	L5, S1, S2		Obturator Internus, Superior Gemellus
Nerve to Piriformis	Posterior division of the ventral rami of S1 and S2		Piriformis
Nerve to Quadratus Femoris and Inferior Gemellus	L4, L5, S1	Sensory branch to hip joint	Quadratus Femoris, Inferior Gemellus
Perforating Cutaneous Nerve	S2, S3	Lower medial aspect of the buttock
Posterior Femoral Cutaneous Nerve	S1, S2, S3	Posterior surface of the thigh, leg, and perineum (perineal branches and inferior cluneal nerves)
Pudendal Nerve	S2, S3, S4	Skin of penis, clitoris, most of the perineum	Muscles of the perineum
Sciatic Nerve	L4, L5, S1, S2, S3	No direct sensory function, but has indirect sensory supply to the foot (tibial nerve, common peroneal nerve) and leg (except medial portion which is saphenous nerve)	Extensive motor innervation to thigh, leg, ankle, foot.
Superior Gluteal Nerve	L4, L5, S1	Skin of buttock	Gluteus Medius, Gluteus Minimus, Tensor Fascia Lata

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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