Sacral Plexus Part 1 Flashcards
What anterior primary rami form the sacral plexus?
L4, L5, S1-S3 and part of S4
Which rami contribute to the sacral plexus by way of the lumbosacral trunk?
L4 and L5
What muscle does the sacral plexus form on the anterior surface of?
piriformis
When do the nerve roots that form the sacral plexus divide into anterior and posterior divisions?
shortly after exiting their IVF/sacral foramen
What roots contribute fibers to the nerve to the quadratus femoris and gemellus inferior?
L4, L5, and S1 nerves
Virtually every major nerve of the sacral plexus leaves the pelvic cavity via what opening?
greater sciatic foramen
T/F: the nerve to the quadratus femoris and gemellus inferior leaves the pelvis thru the greater sciatic foramen to supply muscles which contribute to lateral rotation and abduction of the thigh.
False; should say aDDuction
What nerve exits the pelvis thru the greater sciatic foramen, re-enters via the lesser sciatic foramen and supplies muscles that contribute to lateral rotation and abduction of the thigh?
nerve to the obturator internus and gemellus superior
What roots contribute to the nerve to the obturator internus and gemellus superior?
L5, S1, and S2
T/F: the nerve to the obturator internus and gemellus superior re-enters the pelvis via the lesser sciatic foramen to supply the gemellus superior.
False; re-enters to supply obturator internus– nerve to obturator internus and gemellus superior gives off branches to gemellus superior after exiting greater sciatic foramen before re-entering pelvis
What roots contribute to the pudendal nerve?
S2, S3, and S4
which nerve leaves the pelvis via the greater sciatic foramen, arches around the ischial spine and into the perineum via the lesser sciatic nerve?
pudendal nerve
What structure does the pudendal nerve travel through inferior to the pubic symphysis to reach the dorsal side of the penis/clitoris?
pudendal canal
What are the 3 major branches that come off of the pudendal nerve inside the pudendal canal?
inferior rectal nerves, perineal nerve, and the terminal branch of the pudendal nerve (dorsal nerve of the penis/clitoris)
Which branch of the pudendal nerve carries sensory info from the skin around the anus and inferior 2/3 of the anal canal?
inferior rectal nerves
What nerve is the motor supply to the external anal sphincter?
inferior rectal nerve of the pudendal nerve
After the perineal nerve is given off of the pudendal nerve in the pudendal canal, what does it divide into?
deep and superficial branches
What muscles are supplied by the deep branches of the perineal nerve?
external anal sphincter, bulbospongiosus, ischiocavernosus, and superficial transverse perineus
What kind of info is carried by the superficial branches of the perineal nerve?
sensory
What area is supplied by the superficial branches of the perineal nerve in males? in females?
posterior scrotum, urethral mucosa, and bulb of penis;
labium majus, external urethral orifice, and vestibule
what muscles are supplied by the terminal branch of the pudendal nerve?
deep transverse perineus and urethral sphincter muscles
What is the name given to the terminal branch of the pudendal nerve?
dorsal nerve of the penis/clitoris
What areas does the terminal branch of the pudendal nerve carry sensory info from?
in males: corpus cavernosum, glans penis, and skin covering penis;
in females: corpus cavernosum and clitoris
Individual muscular branches off the sacral plexus supply the levator ani and coccygeus muscles. Where do these fibers originate?
S4
