where is the sacral plexus located
on the surface of the posterior pelvic wall, anterior to the piriformis muscle.
The sacral plexus is formed by the
anterior rami (divisions) of the sacral spinal nerves S1, S2, S3 and S4.
It also receives contributions from the lumbar spinal nerves L4 and L5.
At each vertebral level (S1-S4)....
paired spinal nerves leave the spinal cord via the intervertebral foramina of the vertebral column.
The anterior rami of the S1-S4 spinal roots (and the lumbosacral trunk) divide into several cords. These cords then combine together to form the five major peripheral nerves of the sacral plexus.
name the 5 major peripheral nerves of the sacral plexus
superior gluteal nerve
inferior gluteal nerve
sciatic nerve and its divisions
posterior femoral cutaenous nerve
as the nerves descend down the posteiro pelvic wall, they have 2 main destination:
Leave the pelvis via the greater sciatic foramen – these nerves enter the gluteal region of the lower limb, innervating the structures there.
- Remain in the pelvis – these nerves innervate the pelvic muscles, organs and perineum.
superior gluteal nerve
The superior gluteal nerve leaves the pelvis via the greater sciatic foramen, entering the gluteal region superiorly to the piriformis muscle. It is accompanied by the superior gluteal artery and vein for much of its course.
roots of the superior gluteal nerve
L4, L5, S1
motor function of the superior gluteal nerve
Innervates the gluteus minimus, gluteus medius and tensor fascia lata.
sensory function of the superior gluteal nerve
Inferior Gluteal Nerve
The inferior gluteal nerve leaves the pelvis via the greater sciatic foramen, entering the gluteal region inferiorly to the piriformis muscle.
It is accompanied by the inferior gluteal artery and vein for much of its course.
roots of the inferior gluteal nerve
L5, S1, S2
Motor function of the inferior gluteal nerve
innervates gluteus maximus
Sensory function of the inferior gluteal nerve
roots of the sciatic nerve
L4, L5, S1, S2, S3
motor function of the sciatic nerve
Tibial portion – Innervates the muscles in the posterior compartment of the thigh (apart from the short head of the biceps femoris), and the hamstring component of adductor magnus. Innervates all the muscles in the posterior compartment of the leg and sole of the foot.
Common fibular portion – Short head of biceps femoris, all muscles in the anterior and lateral compartments of the leg and extensor digitorum brevis.
sensory function of the sciatic nerve
Tibial portion: supplies the skin of the posterolateral leg, lateral foot and the sole of the foot.
Common fibular portion: supplies the skin of the lateral leg and the dorsum of the foot.
Posterior Femoral Cutaneous
The posterior cutaneous nerve of thigh leaves the pelvis via the greater sciatic foramen, entering the gluteal region inferiorly to the piriformis muscle. It descends deep to the gluteus maximus and runs down the back of the thigh to the knee.
roots of the posterior femoral cutaneous
S1, S2, S3
Motor fucntion of the posterior femoral cutaenous
Sensory fucntion of the posterior femoral cutaneous
Innervates the skin on the posterior surface of the thigh and leg. Also innervates the skin of the perineum.
This nerve leaves the pelvis via the greater sciatic foramen, then re-enters via the lesser sciatic foramen. It moves anterosuperiorly along the lateral wall of the ischiorectal fossa, and terminates by dividing into several branches.
roots of the pudendal nerve
S2, S3, S4
Motor function of the pudendal nerve
Innervates the skeletal muscles in the perineum, the external urethral sphincter, the external anal sphincter, levator ani.
sensory function of the pudendal nerve
innervates the penis and clitoris and most of the skin of the perineum
In addition to the five major nerves of the sacral plexus, there are a number of smaller branches. These tend to be nerves that directly supplying muscles (with the exception of the perforating cutaneous nerve, which supplies the skin over the inferior gluteal region and the pelvic splanchnic nerves, which innervate the abdominal viscera):
Nerve to piriformis
Nerve to obturator internus
Nerve to quadratus femoris
way to remeber roots fo the pudendal
S2, S3, S4 keeps poo off the floor!!!!!!!!!!!!!! :)
acronymn for the sacral plexus peripheral nerves
Salmon is so perfectly pink
This stands for Superior Gluteal, Inferior Gluteal, Sciatic, Posteriorcutaneous nerve of thigh, Pudendal.