Posterior branches of sacral nerves
Encyclopedia
The 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
. In some rare cases these nerves break and cause the person's legs to become weak and eventually whither away under the person's weight.
The upper three are covered at their points of exit by the multifidus, and divide into medial and lateral branches.
Posterior sacral foramina
Lateral 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....
. In some rare cases these nerves break and cause the person's legs to become weak and eventually whither away under the person's weight.
The upper three are covered at their points of exit by the multifidus, and divide into medial and lateral branches.