Sacral plexus

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:

Additional images

File:Gray838.png|The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses. File:Sacral plexus schematic.svg|A schematic depiction.

File:Sacral plexus.gif| Diagram of the sacral plexus

Notes

References

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References

1. ''Thieme Atlas of Anatomy'' (2006), pp 470-471
2. ''Thieme Atlas of Anatomy'' (2006), pp 476, 478, 482