Sacral plexus

Template:Infobox Nerve Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

In human anatomy, the sacral plexus is a nerve plexus emerging from the sacral vertebrae (S1-S4), and which provides nerves for the pelvis and lower limbs.

Structure

The sacral plexus is formed by::

the lumbosacral trunk
the anterior division of the first sacral nerve
portions of the anterior divisions of the second and third sacral nerves

The nerves forming the sacral plexus converge toward the lower part of the greater sciatic foramen, and unite to form a flattened band, from the anterior and posterior surfaces of which several branches arise.

The band itself is continued as the sciatic nerve, which splits on the back of the thigh into the tibial nerve and common fibular nerve; these two nerves sometimes arise separately from the plexus, and in all cases their independence can be shown by dissection.

Often, the sacral plexus and the lumbar plexus are considered to be one large nerve plexus, the lumbosacral plexus. The lumbosacral trunk connects the two plexuses.

Relations

The sacral plexus lies on the back of the pelvis between the piriformis muscle and the pelvic fascia. In front of it are the internal iliac artery, internal iliac vein, the ureter, and the sigmoid colon. The superior gluteal artery and vein run between the lumbosacral trunk and the first sacral nerve, and the inferior gluteal artery and vein between the second and third sacral nerves.

All the nerves entering the plexus, with the exception of the third sacral, split into ventral and dorsal divisions, and the nerves arising from these are as follows:

Nerve	Segments	Muscles	Cutaneous
Nerve to quadratus femoris	L4-S1	gemellus inferior, quadratus femoris
Superior gluteal nerve	L4-S1	gluteus medius, gluteus minimus, tensor fasciae latae
Sciatic nerve	L4-S3
* Tibial nerve	L4-S3	posterior compartment	posterolateral leg and foot - medial sural cutaneous nerve
* Common fibular nerve	L4-S3	anterior and lateral compartments	anterolateral leg and foot - Lateral sural cutaneous nerve, medial dorsal cutaneous nerve, intermediate dorsal cutaneous nerve
Nerve to obturator internus	L5-S2	gemellus superior, obturator internus
Inferior gluteal nerve	L5-S2	gluteus maximus
Nerve to piriformis	S1-S2	piriformis
Posterior cutaneous nerve of thigh	S1-S3	-	thigh
Pudendal nerve	S2-S4	bulbospongiosus, deep transverse perineal, ischiocavernosus, sphincter urethrae, superficial transverse perineal	clitoris, penis
Coccygeal nerve	S4-Co1	-	perineum

Additional images

Dissection of side wall of pelvis showing sacral and pudendal plexuses.
The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.