Sacral nerves
Encyclopedia
The five sacral nerves emerge from the sacrum
. Although the vertebral components of the sacrum are fused into a single bone, the sacral vertebrae are still used to number the sacral nerves.
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
. Although the vertebral components of the sacrum are fused into a single bone, the sacral vertebrae are still used to number the sacral nerves.
- Posteriorly, they emerge from the posterior sacral foraminaPosterior sacral foraminaLateral to the articular processes of the sacrum are the four posterior sacral foramina ; they are smaller in size and less regular in form than the anterior, and transmit the posterior divisions of the sacral nerves....
, and form the posterior branches of sacral nervesPosterior branches of sacral nervesThe posterior divisions of the sacral nerves are small, and diminish in size from above downward; they emerge, except the last, through the posterior sacral foramina...
(including the medial clunial nerves).
- Anteriorly, they emerge from the anterior sacral foraminaAnterior sacral foraminaAt the ends of the transverse ridges of the pelvic surface of the sacrum are seen the anterior sacral foramina , four in number on either side, somewhat rounded in form, diminishing in size from above downward, and directed lateralward and forward.They give exit to the anterior divisions of the...
, and contribute to the sacral plexusSacral plexus-External links:*...
(S1-S4) and coccygeal plexusCoccygeal plexusThe coccygeal plexus is a plexus of nerves near the coccyx bone.-Structure:This plexus is formed by the fifth sacral nerve and the coccygeal nerve...
.