piriformis syndrome. Other acute causes of sciatica include coughing, muscular hypertension, and sneezing. Sciatic nerve injury occurs between 0.5% and 2.0%
Sciatic nerve
From Wikipedia, the free encyclopedia
The
sciatic nerve (
; also called
ischiadic nerve,
ischiatic nerve) is a large
nerve in
humans and other
animals. It begins in the
lower back and runs through the
buttock and down the
lower limb. It is the longest and widest single nerve in the
human body, going from the top of the leg to the foot on the posterior aspect.
[1] The sciatic nerve provides the connection to the nervous system for nearly the whole of the
skin of the
leg, the
muscles of the back of the
thigh, and those of the leg and
foot. It is derived from
spinal nerves L4 to
S3. It contains
fibres from both the anterior and posterior divisions of the
lumbosacral plexus.
Structure
The sciatic nerve is formed from the L4 to S3 segments of the
sacral plexus, a collection of nerve fibres that emerge from the
sacral part of the
spinal cord. The fibres unite to form a single nerve in front of the
piriformis muscle. The nerve passes beneath
piriformis and through the
greater sciatic foramen, exiting the
pelvis.
[2]:422-4 From here, it travels down the posterior thigh to the
popliteal fossa. The nerve travels in the
posterior compartment of the thigh behind (superficial to) the
adductor magnus muscle, and is itself in front of (deep to) one head of the
biceps femoris muscle. At some point between the pelvis and popliteal fossa, the nerve divides into its two branches:
[2]:532
The sciatic nerve is the largest nerve in the human body.
[2] :422-4
Development
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This section requires expansion. (March 2014) |
Function
The sciatic nerve supplies sensation to the
skin of the
foot, as well as the entire lower leg (except for its inner side). Sensation to skin to the sole of the foot is provided by the
tibial nerve, and the lower leg and upper surface of the foot via the
common fibular nerve.
[2]:422-4
The sciatic nerve also innervates muscles. In particular:
[2] :422-4
Clinical significance
Sciatica
Pain caused by a compression or irritation of the sciatic nerve by a problem in the lower back is called
sciatica. Common causes of sciatica include the following lower back and hip conditions:
spinal disc herniation,
degenerative disc disease,
lumbar spinal stenosis,
spondylolisthesis, and
piriformis syndrome.
[3] Other acute causes of sciatica include
coughing, muscular
hypertension, and
sneezing.
[4]
Injury
Sciatic nerve injury occurs between 0.5% and 2.0% of the time during
total hip arthroplasty.
[5]
Sciatic nerve palsy is a complication of total hip arthroplasty with an
incidence of 0.2% to 2.8% of the time, or with an incidence of 1.7% to
7.6% following revision.
[6] Following the procedure, in rare cases, a screw, broken piece of trochanteric wire, fragment of
methyl methacrylate bone cement, or
Burch-Schneider metal cage
can impinge on the nerve; this can cause sciatic nerve palsy which may
resolve after the fragment is removed and the nerve freed. The nerve can
be surrounded in oxidized regenerated cellulose to prevent further
scarring. Sciatic nerve palsy can also result from severe
spinal stenosis following the procedure, which can be addressed by
spinal decompression surgery.
[5][7] It is unclear if
inversion therapy is able to decompress the sacral vertebrae, it may only work on the lumbar aspects of the sciatic nerves.
Other disease
Bernese periacetabular
osteotomy
resulted in major nerve deficits in the sciatic or femoral nerves in
2.1% of 1760 patients, of whom approximately half experienced complete
recovery within a mean of 5.5 months.
[8]
Sciatic nerve exploration can be done by
endoscopy in a
minimally invasive procedure to assess lesions of the nerve.
[9] Endoscopic treatment for sciatic nerve entrapment has been investigated in
deep gluteal syndrome; "Patients were treated with sciatic nerve decompression by
resection of fibrovascular scar bands,
piriformis tendon release,
obturator internus, or
quadratus femoris or by
hamstring tendon scarring."
[10]
Society and culture
According to
Jewish law, the sciatic nerve (
Hebrew:
Gid hanasheh) cannot be eaten, to commemorate Jacob's hurt in his struggle with an
Angel.
[11]
See also
Additional images
-
-
Structures surrounding left hip-joint.
-
Nerves of the right lower extremity. Posterior view.
-
-
-
See also
Notes
Left gluteal region, showing surface markings for arteries and sciatic nerve
Tibial and common peroneal nerve (aka common fibular nerve)
Sciatic nerve.
Structures surrounding left hip-joint.
Nerves of the right lower extremity. Posterior view.
Sciatic nerve.
Sciatic nerve.
Sciatic nerve.
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