Sacral Plexus

Front 1

Sciatic Nerve

Back 1

Tibial portion: anterior L4-S3
Common peroneal portion: posterior L4-S2
Runs under piriformis, through greater sciatic foramen
Motor innervation to knee flexors & ALL muscles in leg & foot

Front 2

Superior Gluteal Nerve

Back 2

Posterior division L4-S1
Runs superior to piriformis through greater sciatic foramen between gluteus medius & minimus
Motor innervation gluteus medius & minimus & tensor fascia latae

Front 3

Inferior Gluteal Nerve

Back 3

Posterior division L5-S2
Runs through greater sciatic foramen inferior to piriformis, deep to gluteus maximus & superficial to sciatic nerve
Motor innervation gluteus maximus

Front 4

Quadratus Femoris Nerve

Back 4

Also innervates superior gemillus
Anterior division L4-S1
Runs through the greater sciatic foramen inferior to the piriformis muscle
Motor innervation to those 2 muscles

Front 5

Obterator Internus Nerve

Back 5

Also innervates inferior gemillus
Anterior division L5-S2
Runs through greater sciatic foramen inferior to piriformis the loops back to reenter pelvis through lesser sciatic foramen
Motor innervation to obterator interus & superior gemellus

Front 6

Pudendal Nerve

Back 6

Anterior division S2-S4
Runs through the greater sciatic foramen inferior to the piriformis muscle then loops back to enter perineum through lesser sciatic foramen to enter pudendal canal
Motor innervation to perineum muscles & primary sensory innervation to genitalia

Front 7

Coccygeal & Levator Ani Nerve

Back 7

Anterior division S3-S4
Motor innervation to these 2 muscles

Front 8

Posterior femoral cutaneous nerve

Back 8

Anterior division S2-S3
Posterior division S1-S2
Runs through the greater sciatic foramen inferior to the piriformis muscle, lies alongside the sciatic nerve
Sensory innervation to skin of back of thigh & to skin of lower & lateral butt (gluteal branch) & perineum (perineal branch)

Front 9

Perforating branches of cutaneous nerve

Back 9

Posterior division S2-S3
Pierces sacrotuberal ligament; sensory innervation to skin of medial part of butt fold

Front 10

Piriformis Nerve

Back 10

Posterior division S1-S2
Motor innervation piriformis

Front 11

Pelvic Splanchnic Nerve

Back 11

Anterior division S2-S4
travels to inferior hypogastric plexus

Front 12

Perineal branch

Back 12

Anterior division S4
Descends through coccygeus then runs anterior to external sphincter ani
motor innervation to this muscle & sensory innervation to overlying skin