Sacral Spinal Nerves and Coccygeal Plexus Flashcards
How many sacral spinal nerves typically exist?
10 (5 pairs)
Do sacral spinal nerves descend inside or outside of the dura?
inside (form much of the cauda equina)
T/F: Each sacral spinal nerve divides into an anterior and a posterior primary ramus.
True
Which nerves travel through the sacral foramina
sacral spinal nerves (S1-S4 anterior primary rami through anterior sacral foramina, S1-S4 posterior primary rami through posterior sacral foramina)
What muscles do the medial branches of the posterior primary rami of S1-S3 supply?
adjacent multifidi
The lateral branches of the posterior primary rami of S1-S3 combine with branches from what nerves to supply the skin over the buttocks?
L5 and S4
What do the posterior primary rami of S4 and S5 combine with to supply the skin over the coccyx?
coccygeal posterior rami
Which sacral primary rami travel through the sacral hiatus?
anterior and posterior primary rami of S5
T/F: the posterior primary ramus of S4 does not divide into medial and lateral branches.
True
Which sacral spinal nerve contributes to both the sacral plexus and the coccygeal plexus?
S4 (S1-S4=sacral plexus, S4-Co1=coccygeal plexus
How many sacral sympathetic ganglia usually exist?
usually 3 or 4
T/F: The anterior primary ramus of each sacral nerve will receive postganglionic sympathetic fibers via a white ramus communicans.
False; via a gray ramus communicans
What forms the coccygeal plexus?
anterior rami of S4, S5, and Co 1
What nerves are produced from the coccygeal plexus?
anococcygeal nerves
What do the anococcygeal nerves supply?
sensory info from the skin adjacent to the coccyx and anus (“anal pucker” response)
