Lumbosacral Plexus

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Lumbar and Sacral Plexus.jpg
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.

NerveOriginSensory InnervationMotor Innervation
Femoral NerveL2, L3, L4 anterior rami, posterior divisionsSkin of medial lower leg through saphenous nerveQuadriceps Femoris, Sartorius, Pectineus, Iliacus,
Genitofemoral NerveL1, L2Skin of femoral triangle, lower scrotum/labiaCremasteric muscle in men
Iliohypogastric NerveT12, L1Skin of lower abdomenTransversus Abdominis, Internal Obliques
Ilioinguinal NerveL1Skin to inguinal region, small area of medial thigh, upper scrotum/labia.Transversus Abdominis, Internal Oblique
Lateral Femoral Cutaneous NervePosterior divisions of L2 and L3 spinal nervesAnterolateral thigh
Lumbosacral TrunkL4, L5 (mainly L5)Skin of L5Ankle dorsiflexors, ankle everters, ankle inverters
Obturator NerveL2, L3, L4 anterior ramiSkin of medial thighAdductor Magnus (anterior half), Adductor Longus, Adductor Brevis, Gracilis, Obturator Externus

Sacral Plexus

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

NerveOriginSensory InnervationMotor Innervation
Inferior Gluteal NerveL5, S1, S2Gluteus Maximus
Nerve to Obturator Internus and Superior GemellusL5, S1, S2Obturator Internus, Superior Gemellus
Nerve to PiriformisPosterior division of the ventral rami of S1 and S2Piriformis
Nerve to Quadratus Femoris and Inferior GemellusL4, L5, S1Sensory branch to hip jointQuadratus Femoris, Inferior Gemellus
Perforating Cutaneous NerveS2, S3Lower medial aspect of the buttock
Posterior Femoral Cutaneous NerveS1, S2, S3Posterior surface of the thigh, leg, and perineum (perineal branches and inferior cluneal nerves)
Pudendal NerveS2, S3, S4Skin of penis, clitoris, most of the perineumMuscles of the perineum
Sciatic NerveL4, L5, S1, S2, S3No 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 NerveL4, L5, S1Skin of buttockGluteus Medius, Gluteus Minimus, Tensor Fascia Lata

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


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