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Sciatic nerve
 
 
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The sciatic nerve (also known as the ischiatic nerve) is a large nerve
Nerve

A nerve is an enclosed, cable-like bundle of Peripheral nervous system axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons....
 that starts in the lower back and runs through the buttock and down the lower limb. It is the longest and widest single nerve in the body.

The sciatic supplies nearly the whole of the skin of the leg, the muscles of the back of the thigh, and those of the leg and foot.

nerve enters the lower limb by exiting the pelvis
Pelvis

The pelvis or pelvic girdle is the irregular bone structure located at the base of the spine . In the adult human, it is formed by the sacrum and the coccyx, the caudal part of the axial skeleton, and a pair of hip bones, part of the appendicular skeleton or human leg....
 through the greater sciatic foramen
Greater sciatic foramen

The greater sciatic foramen is a major foramen of the pelvis....
, below the Piriformis muscle and above the superior gemellus muscle
Superior gemellus muscle

The superior gemellus muscle is a muscle of the human body.The Gemelli are two small muscular fasciculi, accessories to the tendon of the Obturator internus which is received into a groove between them....
.

It descends midway between the greater trochanter
Greater trochanter

The greater trochanter of the femur is a large, irregular, quadrilateral eminence.It is directed a little lateralward and backward, and, in the adult, is about 1 cm....
 of the femur
Femur

The femur, or thigh bone, is the most proximal bone of the leg in vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs....
 and the tuberosity of the ischium
Tuberosity of the ischium

Posteriorly, the Superior ramus of the ischium of the ischium forms a large swelling, the tuberosity of the ischium .It marks the lateral boundary of the pelvic outlet....
, and along the back of the thigh to about its lower third, where it divides into two large branches, the tibial
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.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a cutaneous branch that will become the sural nerve...
 and common peroneal nerves
Common fibular nerve

The common peroneal nerve , about one-half the size of the tibial nerve, is derived from the dorsal branches of the fourth and fifth lumbar nerve and the first and second sacral nerves....
.






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The sciatic nerve (also known as the ischiatic nerve) is a large nerve
Nerve

A nerve is an enclosed, cable-like bundle of Peripheral nervous system axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons....
 that starts in the lower back and runs through the buttock and down the lower limb. It is the longest and widest single nerve in the body.

The sciatic supplies nearly the whole of the skin of the leg, the muscles of the back of the thigh, and those of the leg and foot.

Anatomical course

The nerve enters the lower limb by exiting the pelvis
Pelvis

The pelvis or pelvic girdle is the irregular bone structure located at the base of the spine . In the adult human, it is formed by the sacrum and the coccyx, the caudal part of the axial skeleton, and a pair of hip bones, part of the appendicular skeleton or human leg....
 through the greater sciatic foramen
Greater sciatic foramen

The greater sciatic foramen is a major foramen of the pelvis....
, below the Piriformis muscle and above the superior gemellus muscle
Superior gemellus muscle

The superior gemellus muscle is a muscle of the human body.The Gemelli are two small muscular fasciculi, accessories to the tendon of the Obturator internus which is received into a groove between them....
.

It descends midway between the greater trochanter
Greater trochanter

The greater trochanter of the femur is a large, irregular, quadrilateral eminence.It is directed a little lateralward and backward, and, in the adult, is about 1 cm....
 of the femur
Femur

The femur, or thigh bone, is the most proximal bone of the leg in vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs....
 and the tuberosity of the ischium
Tuberosity of the ischium

Posteriorly, the Superior ramus of the ischium of the ischium forms a large swelling, the tuberosity of the ischium .It marks the lateral boundary of the pelvic outlet....
, and along the back of the thigh to about its lower third, where it divides into two large branches, the tibial
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.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a cutaneous branch that will become the sural nerve...
 and common peroneal nerves
Common fibular nerve

The common peroneal nerve , about one-half the size of the tibial nerve, is derived from the dorsal branches of the fourth and fifth lumbar nerve and the first and second sacral nerves....
. This division may take place at any point between the sacral plexus and the lower third of the thigh. When it occurs at the plexus, the common peroneal nerve usually pierces the Piriformis muscles.

In the upper part of its course, the nerve rests upon the posterior surface of the ischium, the nerve to the Quadratus femoris, the Obturator internus and Gemelli
Gemelli

Gemelli is Italian for twins.* Agostino Gemelli is an Italian psychologist.* Agostino Gemelli University Polyclinic is a teaching hospital in Rome....
; it is accompanied by the posterior femoral cutaneous nerve and the inferior gluteal artery
Inferior gluteal artery

The inferior gluteal artery , the larger 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....
, and is covered by the Gluteus maximus.

Lower down, it lies upon the Adductor magnus, and is crossed obliquely by the long head of the Biceps femoris.

Branches

The nerve gives off articular and muscular branches.

  • The articular branches (rami articulares) arise from the upper part of the nerve and supply the hip-joint, perforating the posterior part of its capsule; they are sometimes derived from the sacral plexus
    Sacral plexus

    In human anatomy, the sacral plexus is a nerve plexus which, as part of the lumbosacral plexus, emerges from the sacral vertebrae , and which provides motor and sensory nerves for the posterior thigh, most of the lower leg, the entire foot, and part of the pelvis....
    .


  • The muscular branches (rami musculares) are distributed to the following muscles of the lower limb: Biceps femoris, Semitendinosus, Semimembranosus, and Adductor magnus. The nerve to the short head of the Biceps femoris comes from the common peroneal part of the sciatic, while the other muscular branches arise from the tibial portion, as may be seen in those cases where there is a high division of the sciatic nerve.


The muscular branch eventually gives off the tibial nerve
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.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a cutaneous branch that will become the sural nerve...
 and common peroneal nerve, which innervates the muscles of the (lower) leg. The tibial nerve goes on to innervate all muscles of the foot except the extensor digitorum brevis (peroneal nerve).

Pathology

Pain caused by a compression or irritation of the sciatic nerve by a problem in the lower back is called sciatica
Sciatica

Sciatica is a set of symptoms including pain that may be caused by general compression and/or irritation of one of five nerve roots that give rise to the sciatic nerve, or by compression or irritation of the sciatic nerve itself....
. Common causes of sciatica include the following low back conditions: spinal disc herniation
Spinal disc herniation

A spinal disc herniation ', incorrectly called a "slipped disc", is a medical condition affecting the Vertebral column, in which a tear in the outer, fibrous ring of an intervertebral disc ' allows the soft, central portion to hernia....
, degenerative disc disease
Degenerative disc disease

Degeneration of the intervertebral disc, which is often called "degenerative disc disease" of the vertebral column, is a condition that can be painful and can greatly affect the quality of one's life....
, spinal stenosis
Spinal stenosis

Spinal stenosis is a medical condition in which the spinal canal narrows and compresses the spinal cord and nerves. This is usually due to the natural process of spinal degeneration that occurs with aging....
, and spondylolisthesis
Spondylolisthesis

Spondylolisthesis describes the anterior displacement of a vertebra or the vertebrae column in relation to the vertebrae below. It was first described in 1782 by Belgium obstetrician, Dr....
.

In religion

In the Jewish religion, consumption of the sciatic nerve is forbidden, even from otherwise kosher and properly slaughtered animals. This is based on the prohibition mentioned in the Biblical account (Genesis
Genesis

Genesis or Breishit is the first book of the Bible used by Judaism and Christianity, and the first of five books of the Pentateuch or Torah....
 chapter 32) of Jacob
Jacob

According to the Hebrew Bible, Jacob , also known as Israel , was the third Biblical patriarchs and the ancestor of the twelve Israelites....
 being wounded while wrestling with an angel
Jacob Wrestling with the Angel

Jacob Wrestling with the Angel is a Bible story commonly depicted in art. The story appears in chapter 32 of Genesis and chapter 12 of the Book of Hosea....
. The sciatic nerve is known in Hebrew as the gid hanasheh
Gid hanasheh

The gid hanosheh is the sciatic nerve that may not be eaten by Jews according to Halacha ....
. The process of removing the sciatic nerve (as well as certain large blood vessels and forbidden fats) from the surrounding meat is known as nikkur, or "deveining." Since this is a difficult and delicate process, cuts from an animal's hindquarters (including the Filet mignon
Filet mignon

Filet mignon is a steak cut of beef taken from the beef tenderloin, or psoas major of the steer or heifer.The beef tenderloin runs along either side of the vertebral column, and is usually harvested as two long snake-shaped cuts of beef....
) are generally not sold as kosher.

Additional images


See also

  • Sciatica
    Sciatica

    Sciatica is a set of symptoms including pain that may be caused by general compression and/or irritation of one of five nerve roots that give rise to the sciatic nerve, or by compression or irritation of the sciatic nerve itself....


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