human anatomy The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a he ...

, the sacral plexus is a

nerve plexus A nerve plexus is a plexus (branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. There are five spinal nerve ple ...

which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

. It is part of the

lumbosacral plexus The anterior divisions of the lumbar nerves, sacral nerves, and coccygeal nerve form the lumbosacral plexus, the first lumbar nerve being frequently joined by a branch from the twelfth thoracic. For descriptive purposes this plexus is usually divi ...

and emerges from the

lumbar vertebrae The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...

and sacral vertebrae (L4-S4).''Thieme Atlas of Anatomy'' (2006), pp 470-471 A sacral

plexopathy Plexopathy is a disorder of the wikt:network, network of nerves in the brachial plexus, brachial or lumbosacral plexus. Symptoms include pain, muscle weakness, and sensory deficits (numbness). Types There are two main types of plexopathy, based on ...

is a disorder affecting the nerves of the sacral plexus, usually caused by trauma, nerve compression, vascular disease, or infection. Symptoms may include pain, loss of motor control, and sensory deficits.

Structure

The sacral plexus is formed by: * the

lumbosacral trunk The lumbosacral trunk is nervous tissue that connects the lumbar plexus with the sacral plexus. Structure The lumbosacral trunk comprises the whole of the ventral rami of L5 and a part of L4. It appears at the medial margin of the psoas major ...

* the anterior division of the first

sacral nerve A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into th ...

* 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 The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus. Structure Popliteal fossa The tibial nerve is the larger terminal branch of the sciatic nerve with root val ...

and

common fibular nerve The common fibular nerve (also known as the common peroneal nerve, external popliteal nerve, or lateral popliteal nerve) is a nerve in the lower leg that provides sensation over the posterolateral part of the leg and the knee joint. It divides at ...

; 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 The lumbar plexus is a web of nerves (a nervous plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the Ventral ramus of spinal nerve, divisions of the first four lumbar nerves (L1-L4) and ...

are considered to be one large nerve plexus, the

. The

connects the two plexuses.

Relations

The sacral plexus lies on the back of the pelvis in front of the

piriformis The piriformis muscle () is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group. The piriformis muscle has its origin upon the front surface of the sacrum, and in ...

muscle and the

pelvic fascia The pelvic fasciae are the fascia of the pelvis and can be divided into: * (a) the fascial sheaths of ** the Obturator internus muscle ( Fascia of the Obturator internus) ** the Piriformis muscle (Fascia of the Piriformis) ** the pelvic floor * ...

. In front of it are the

internal iliac artery The internal iliac artery (formerly known as the hypogastric artery) is the main artery of the pelvis. Structure The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial compa ...

, internal iliac vein, the

ureter The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...

, and the sigmoid colon. The

superior gluteal artery The superior gluteal artery is the largest and final branch of the internal iliac artery. It is the continuation of the posterior division of that vessel. It is a short artery which runs backward between the lumbosacral trunk and the first sacral ...

and vein run between the

and the first sacral nerve, and the

inferior gluteal artery The inferior gluteal artery (sciatic artery), the smaller of the two terminal branches of the anterior trunk of the internal iliac artery, is distributed chiefly to the buttock and back of the thigh. It passes down on the sacral plexus of nerves ...

and vein between the second and third sacral nerves.

Nerves formed

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 of the table below:

Additional images

File:Gray838.png, The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses. File:Sacral plexus schematic.svg, A schematic depiction. File:Sacral plexus.gif, diagram of the Sacral plexus

Notes

References

External links

* * *
Illustration at backpain-guide.com
{{Authority control Nerve plexus Spinal nerves Nerves of the lower limb and lower torso