human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross ...

, 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 (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

. It is part of the lumbosacral plexus and emerges from the

lumbar vertebrae The lumbar vertebrae are located between the thoracic vertebrae and pelvis. They form the lower part of the back in humans, and the tail end of the back in quadrupeds. In humans, there are five lumbar vertebrae. The term is used to describe t ...

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

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

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 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 The sciatic nerve, also called the ischiadic nerve, is a large nerve in humans and other vertebrate animals. It is the largest branch of the sacral plexus and runs alongside the hip joint and down the right lower limb. It is the longest and widest ...

, 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; 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 nerve plexus) in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1–L4) and from contributions of the su ...

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 in front of the piriformis muscle and the pelvic fascia. 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 com ...

internal iliac vein The internal iliac vein (hypogastric vein) begins near the upper part of the greater sciatic foramen, passes upward behind and slightly medial to the internal iliac artery and, at the brim of the pelvis, joins with the external iliac vein to for ...

, the

ureter The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lin ...

, and the

sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...

. The

superior gluteal artery The superior gluteal artery is the terminal branch of the posterior division of the internal iliac artery. It exits the pelvis through the greater sciatic foramen before splitting into a superficial branch and a deep branch. Structure Origin Th ...

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.

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

* * * {{Authority control Nerve plexus Spinal nerves Nerves of the lower limb and lower torso