The sacral plexus is a network of nerves that lies in the sacral region, anterior to the pelvic surface of the sacrum and the deep surface of the piriformis muscle (Read more!). Additionally, the internal iliac vessels and ureter lie anterior to the sacral plexus. This plexus appears triangular in shape, with its apex pointing downward.

The sacral plexus is formed by the ventral rami of the fourth lumbar to fourth sacral nerves (L4 - S4). The sacral ventral rami enter the pelvic cavity through the anterior sacral foramina. Please note that the sacral plexus receives only part of the ventral ramus of the fourth lumbar nerve (L4) via the lumbosacral trunk (Read more!).

The lumbosacral trunk crosses the sacroiliac joint and joins the sacral plexus, serving as a connection between the lumbar plexus and sacral plexus. It is fixed to the sacral ala by fibrous connective tissue. Additionally, part of the ventral ramus of the fourth sacral nerve (S4) joins the coccygeal plexus, so this nerve only partially contributes to the formation of the sacral plexus.

The following nerves arise from the sacral plexus:

Superior gluteal nerve (L4 - S1) (Read more!)
Inferior gluteal nerve (L5 - S2) (Read more!)
Nerve to piriformis muscle (S1 - S2) (Read more!)
Perforating cutaneous nerve (S2 - S3) (Read more!)
Nerve to obturator internus (L5 - S2) (Read more!)
Nerve to quadratus femoris muscle (L4 - S1) (Read more!)
Pudendal nerve (S2 - S4) (Read more!)
Nerve to levator ani (S3 - S4) (Read more!)
Nerve to coccygeus muscle (S4 - S5, Co1) (Read more!)
Posterior femoral cutaneous nerve (S1 - S3) (Read more!)
Sciatic nerve (L4 - S3) (Read more!)

The sacral plexus is a complex structure and is divided into two divisions (or parts) - anterior and posterior. The superior gluteal nerve, inferior gluteal nerve, nerve to piriformis, and perforating cutaneous nerve represent the posterior division of the sacral plexus, while the nerve to obturator internus, nerve to quadratus femoris, pudendal nerve, nerve to levator ani, and nerve to coccygeus represent the anterior division. The posterior femoral cutaneous nerve and sciatic nerve arise from both the anterior and posterior divisions of the sacral plexus.

The sacral plexus provides motor and sensory supply to the structures of the lower limb, pelvis, and perineum. Additionally, it also gives rise to pelvic splanchnic nerves (S2 - S4), which provide parasympathetic innervation to the pelvic viscera.

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Sacral plexus