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| Nerve: Sacral plexus | |
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| Plan of sacral and pudendal plexuses. | |
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| Relations of the sacral plexus. Dissection of side wall of pelvis showing sacral and pudendal plexuses. | |
| Latin | plexus sacralis |
| Gray's | subject #213 957 |
| From | L4-L5, S1-S4 |
| Dorlands / Elsevier |
p_24/12648416 |
In human anatomy, the sacral plexus is a nerve plexus emerging from the sacral vertebrae (S1-S4), and which provides nerves for the pelvis and lower limbs.
Contents |
Composition
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 (Mr.V) 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.
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:
| Nerve | Segments | Muscles | Cutaneous |
| Nerve to quadratus femoris | L4-S1 | gemellus inferior, quadratus femoris | |
| Superior gluteal nerve | L4-S1 | gluteus medius, gluteus minimus, tensor fasciae latae | |
| Sciatic nerve | L4-S3 | ||
| * Tibial nerve | L4-S3 | posterior compartment | posterolateral leg and foot - medial sural cutaneous nerve |
| * Common fibular nerve | L4-S2 | anterior compartment and lateral compartment | 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 |
| Perforating cutaneous nerve | S2-S3 | - | - |
| Pudendal nerve | S2-S4 | bulbospongiosus, deep transverse perineal, ischiocavernosus, sphincter urethrae, superficial transverse perineal | clitoris, penis |
| Coccygeal nerve | S4-Co1 | - | perineum |
Additional images
 The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses. |
See also
External links
- MeSH Lumbosacral+Plexus
- Cross section at UV pembody/body15a
- Mnemonic at medicalmnemonics.com 3544 2382
- Sacral+plexus at eMedicine Dictionary
- 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.
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Wikipedia content modification information:
- This page was last modified on 5 October 2008, at 07:14.
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