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|Nerve: Sacral plexus|
|Plan of sacral and pudendal plexuses.|
|Gray's||subject #213 957|
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.
The sacral plexus lies on the back of the pelvis between 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.
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:
|Nerve to quadratus femoris||L4-S1||gemellus inferior, quadratus femoris|
|Superior gluteal nerve||L4-S1||gluteus medius, gluteus minimus, tensor fasciae latae|
|* Tibial nerve||L4-S3||posterior compartment||posterolateral leg and foot - medial sural cutaneous nerve|
|* Common fibular nerve||L4-S3||anterior and lateral compartments||anterolateral leg and foot - Lateral sural cutaneous nerve, medial dorsal cutaneous nerve, intermediate dorsal cutaneous nerve|
|Nerve to obturator internus||L5-S2||gemellus superior, obturator internus|
|Inferior gluteal nerve||L5-S2||gluteus maximus|
|Nerve to piriformis||S1-S2||piriformis|
|Posterior cutaneous nerve of thigh||S1-S3||-||thigh|
|Pudendal nerve||S2-S4||bulbospongiosus, deep transverse perineal, ischiocavernosus, sphincter urethrae, superficial transverse perineal||clitoris, penis|
- Dictionary at eMedicine Sacral+plexus
- Illustration at preventdisease.com
- Illustration at backpain-guide.com
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
Nerves: spinal nerves
lumbar plexus: iliohypogastric - ilioinguinal - genitofemoral (femoral branch/lumboinguinal, genital branch) - lateral cutaneous of thigh (patellar) - obturator (anterior, cutaneous, posterior, accessory) - femoral (anterior cutaneous branches, saphenous)
sacral/coccygeal plexus: to quadratus femoris - to obturator internus - to the piriformis - superior gluteal - inferior gluteal - posterior cutaneous of thigh (inferior cluneal, perineal branches)
sciatic: tibial (medial sural cutaneous, sural, medial calcaneal, medial plantar, lateral plantar) - common fibular (lateral sural cutaneous, deep fibular, superficial fibular, medial dorsal cutaneous, intermediate dorsal cutaneous)
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