In human anatomy, the sacral plexus is a nerve plexus which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis. It is part of the lumbosacral plexus and emerges from the lumbar vertebrae and sacral vertebrae (L4-S4).Thieme Atlas of Anatomy (2006), pp 470-471 A sacral plexopathy is a disorder affecting the nerves of the sacral plexus, usually caused by trauma, nerve compression, vascular disease, or infection. Symptoms may include pain, loss of motor control, and sensory deficits.
Structure The sacral plexus is formed by: the lumbosacral trunk the anterior division of the first sacral nerve portions of the anterior divisions of the second and third sacral nerves The nerves forming the sacral plexus converge toward the lower part of the greater sciatic foramen, and unite to form a flattened band, from the anterior and posterior surfaces of which several branches arise. The band itself is continued as the sciatic nerve, which splits on the back of the thigh into the tibial nerve and common fibular nerve; these two nerves sometimes arise separately from the plexus, and in all cases their independence can be shown by dissection. Often, the sacral plexus and the lumbar plexus are considered to be one large nerve plexus, the lumbosacral plexus. The lumbosacral trunk connects the two plexuses.
Relations The sacral plexus lies on the back of the pelvis in front of the piriformis muscle and the pelvic fascia. In front of it are the internal iliac artery, internal iliac vein, the ureter, and the sigmoid colon. The superior gluteal artery and vein run between the lumbosacral trunk and the first sacral nerve, and the inferior gluteal artery and vein between the second and third sacral nerves.
Nerves formed All the nerves entering the plexus, with the exception of the third sacral, split into ventral and dorsal divisions, and the nerves arising from these are as follows of the table below:
+ Nerves of the sacral plexusThieme Atlas of Anatomy (2006), pp 476, 478, 482 Nerve Segment Innervated muscles Cutaneous branches Superior gluteal L4-S1 Gluteus mediusGluteus minimusTensor fasciae latae Inferior gluteal L5-S2 Gluteus maximus Posterior cutaneous femoral Inferior cluneal nerves Perineal branches S1-S3
Perforating cutaneous S2-S3
Direct branches from plexus Piriformis S1-2 Piriformis
Obturator internus L5, S1-2 Obturator internus and Superior gemellus Quadratus femoris L4-5, S1 Quadratus femoris and Inferior gemellus Sciatic Sciatic L4-S3 Semitendinosus (Tib)Semimembranosus (Tib)Biceps femoris Long head (Tib) Short head (Fib) Adductor magnus (medial part, Tib) Common fibular L4-S2
Lateral sural cutaneousCommunicating fibular Superficial fibular
Fibularis longusFibularis brevis Medial dorsal cutaneousIntermediate dorsal cutaneous Deep fibular
Tibialis anteriorExtensor digitorum longusExtensor digitorum brevisExtensor hallucis longusExtensor hallucis brevisFibularis tertius Lateral cutaneous nerve of big toeIntermediate dorsal cutaneous Tibial nerve L4-S3 Triceps surae(Gastrocnemius, Soleus)PopliteusPlantarisTibialis posteriorFlexor digitorum longusFlexor hallucis longus Medial sural cutaneousMedial calcanealLateral dorsal cutaneous Medial plantar
Abductor hallucisFlexor digitorum brevisFlexor hallucis brevis (medial head)Lumbrical (only first) Proper digital plantar Lateral plantar
Flexor hallucis brevis (lateral head)Quadratus plantaeAbductor digiti minimiFlexor digiti minimiLumbrical (second third and fourth)Plantar interossei (first to third)Dorsal interossei (first to fifth)Adductor hallucis Proper plantar digital Pudendal and coccygeal Pudendal(Pudendal plexus) S2-S4 Muscles of the pelvic floor:Levator aniSuperficial transverse perinealDeep transverse perinealBulbospongiosusIschiocavernosusSphincter anus externusUrethral sphincter Inferior rectalPerineal Posterior scrotal/labial Dorsal penis/clitoris prostatic urethra./vagina Coccygeal(Coccygeal plexus) S5-Co1 Coccygeus AnococcygealDorsal branches
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See also Cervical plexus Brachial plexus Lumbar plexus Coccygeal plexus Lumbosacral plexus Nerve plexus Sciatic nerve Pudendal nerve Posterior femoral cutaneous nerve Superior gluteal nerve Inferior gluteal nerve
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