Sacral Plexus Part 2 (Posterior division) Flashcards
What nerve supplies the piriformis muscle and which roots contribute fibers?
nerve to the piriformis; fibers from S1 and S2
What roots contribute fibers to the superior gluteal nerve?
L4, L5, and S1
After the superior gluteal nerve exits the pelvis via the greater sciatic foramen, what does it split into?
superior and inferior branches
What muscle does the superior gluteal nerve exit the pelivs superior to?
piriformis
T/F: the inferior branches of the superior gluteal nerve supply the gluteus maximus.
False; inferior branches of superior gluteal nerve supply the gluteus medius, gluteus minimis and tensor fascia lata
What muscles are supplied by the superior branches of the superior gluteal nerve?
gluteus medius and minimus
What nerve leaves the pelvis via the greater sciatic foramen, inferior to the piriformis, to supply the gluteus maximus? what roots contribute fibers?
inferior gluteal nerve;
L5, S1, and S2
What roots contribute to the perforating cutaneous nerve?
S2 and S3
How does the perforating cutaneous nerve get its name?
it penetrates the sacrotuberous ligament on its way to the lower medial aspects of the buttocks
T/F: the perforating cutaneous nerve may be formed by a branch off the pudendal nerve or be absent altogether.
True
what two nerves are formed by both anterior and posterior divisions of the sacral plexus?
posterior cutaneous nerve of the thigh and sciatic nerve
What roots/divisions form the posterior cutaneous nerve of the thigh?
anterior divisions of S2 and S3 and posterior divisions of S1 and S2
What nerve leaves the pelvis via the greater sciatic foramen, descends thru the posterior thigh and inferior to the leg where it ultimately communicates with the sural nerve?
posterior cutaneous nerve of the thigh
What skin is supplied by the posterior cutaneous nerve of the thigh?
skin of the posterior and medial thigh
What is the largest nerve in the human body?
sciatic nerve
The sciatic nerve is commonly about 2 cm in diameter and formed by two nerves. What are the two nerves that combine to form the sciatic nerve?
tibial and common fibular nerves
The tibial nerve is more medial than the common fibular nerve. Where do the fibers of the tibial nerve come from?
the anterior divisions of the L4-S3 nerves
Where do the fibers of the common fibular nerve come from?
The posterior divisions of the L4-S2
T/F: the sciatic nerve leaves the pelvis via the greater sciatic foramen, below the piriformis, with both parts in individual sheaths.
False; both parts are in a common sheath
What muscle does the sciatic nerve travel on the posterior aspect of in the thigh?
adductor magnus
Where does the sciatic nerve split into its tibial and common fibular components?
about 2/3 of the way to the knee (lower 3rd of the thigh)
T/F: the point at which the sciatic nerve may be further or the two parts may be separate all the way.
True
What muscle does the common fibular nerve give off branches to in the thigh before separating from tibial nerve fibers?
biceps femoris (short head)
After separating from the tibial nerve, the common fibular nerve follows its course around the fibula where it gives off an articular branch. What joint does the common fibular nerve send an articular branch to upon reaching the antero-lateral aspect of the leg?
knee joint
