The sacral plexus (plexus sacralis) is a nerve plexus that offers motor and sensory nerves because that the posterior thigh, most of the lower leg, the entire foot, and component of the pelvis (see the adhering to image). It is component of the bigger lumbosacral plexus. The sacral plexus is derived from the anterior rami of spinal nerves L4, L5, S1, S2, S3, and also S4. Each of these anterior rami provides rise to anterior and also posterior branches. The anterior branches it is provided flexor muscle of the lower limb, and posterior branches supply the extensor and also abductor muscles.

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Sacral plexus. Sagittal view, pelvis.
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The sacral plexus is developed by the union the the lumbosacral trunk (from the anterior rami the L4 and L5) and also the anterior rami that the first, second, third, and also fourth sacral nerves. The anterior rami that the upper 4 sacral nerves go into the pelvis v the anterior sacral foramina; the anterior rami the the 5th sacral nerve enter in between the sacrum and coccyx. <1> (See the adhering to image.)


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Sacral plexus, anterior view.

The nerves creating the sacral plexus converge towards the lower part of the greater sciatic foramen and unite to form a flattened band.


The band continues primarily together the sciatic nerve, i m sorry splits in the back of the thigh into the tibial nerve and common fibular nerve. This 2 nerves sometimes arise separately from the plexus, and also in all cases their independence can be presented by dissection.


The anterior rami the the an initial and second sacral nerves space large; the third, fourth, and fifth diminish progressively in size. Every receives a gray ramus communicans native the corresponding ganglion the the sorry trunk. From the second, third, and also fourth sacral nerves, a pelvic splanchnic nerve is given to the inferior hypogastric plexus. These are parasympathetic fibers the supply the hindgut and the pelvic viscera.


The sacral plexus lies in the earlier of the pelvis in between the piriformis muscle and also the pelvis fascia. In prior of it room the internal iliac artery, inner iliac vein, the ureter, and also the rectum. The exceptional gluteal artery and also vein generally run in between the lumbosacral trunk and the first sacral nerve, and the inferior gluteal artery and also vein regularly runs in between the 2nd and third sacral nerves.


All the nerve root entering the plexus split into anterior and posterior divisions, and the nerves occurring from these space as adheres to (see the image below):


Nerve to the Quadratus Femoris and Gemellus Inferior

The nerve come the quadratus femoris and also gemellus inferior arises from the anterior divisions of the fourth and fifth lumbar and first sacral nerve roots. It leaves the pelvis with the higher sciatic foramen, below the piriformis, and runs under in prior of the sciatic nerve, the gemelli, and also the tendon that the obturator internus, climate enters the anterior surface of the quadratus femoris and also gemellus worse muscles. This nerve offers an articular branch come the i know well joint.


Nerve to the Obturator Internus and also Gemellus Superior

The nerve come the obturator internus and also gemellus premium arises native the anterior department of the fifth lumbar and an initial and 2nd sacral nerve roots. It pipeline the pelvis v the greater sciatic foramen listed below the piriformis and gives off the branch to the gemellus superior, beginning the upper part of the posterior surface of this muscle. This nerve then the cross the ischial spine, start the perineum through the lesser sciatic foramen, and also pierces the pelvic surface ar of the obturator internus muscle.


Nerve come the Piriformis

The nerve to the piriformis occurs from the posterior divisions of the an initial and 2nd sacral nerve roots and enters the anterior surface of the muscle.


Superior and also Inferior Gluteal Nerves

The exceptional gluteal nerve occurs from the posterior departments of the fourth and also fifth lumbar and an initial sacral nerve roots. It leaves the pelvis v the greater sciatic foramen above the piriformis, add by the remarkable gluteal vessels, and also divides right into a superior and an inferior branch. The premium branch accompanies the upper branch of the deep department of the superior gluteal artery and also ends in the gluteus minimus. The inferior division gives filaments to the gluteus medius and also minimus and ends in the tensor fascia lata.


The inferior gluteal nerve arises from the posterior departments of the fifth lumbar and very first and second sacral nerve roots. It pipeline the pelvis v the better sciatic foramen, below the piriformis, and divides right into branches that enter the deep surface of the gluteus maximus.


Posterior Femoral Cutaneous Nerve

The posterior femoral cutaneous nerve is dispersed to the skin that the perineum and posterior surface of the lower part of the buttock, thigh, and leg (see the complying with image). It arises partially from the posterior divisions of the an initial and second sacral nerve roots and also from the anterior departments of the 2nd and 3rd sacral nerve roots.


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chart of the segmental circulation of the cutaneous nerves that the lower extremity.

The posterior femoral cutaneous nerve proceeds from the pelvis through the greater sciatic foramen listed below the piriformis; it climate descends in ~ the gluteus maximus with the inferior gluteal artery and also runs under the back of the thigh beneath the fascia lata and over the long head of the biceps femoris come the back of the knee. Here, that pierces the deep fascia and accompanies the little saphenous vein to about the center of the ago of the leg, with its terminal twigs communicating with the sural nerve. The branches space all cutaneous and are dispersed to the gluteal region, the perineum, and the earlier of the thigh and also leg, together follows:


Inferior cluneal branches turn upward about the reduced border of the gluteus maximus and also supply the skin covering the lower and also lateral part of the muscle


Perineal braches curve forward below and also in front of the ischial tuberosity, pierce the fascia lata, and also run forward beneath the superficial fascia of the perineum to the skin that the scrotum in the male and of the labium majus in the female


Branches to the ago of the thigh and also leg consist of of countless filaments acquired from both sides of the nerve and distributed to the skin covering the back and medial side of the thigh, the popliteal fossa, and also the upper component of the earlier of the leg


Sciatic Nerve

The sciatic supplies virtually the totality of the skin that the leg, the muscles of the ago of the thigh, and also those of the leg and foot. That is the largest nerve in the body, measuring 2 cm in breadth, and is also the extension of the flattened back of the sacral plexus. The sciatic nerve passes out of the pelvis with the greater sciatic foramen, below the piriformis muscle. That descends in between the higher trochanter the the femur and also the tuberosity of the ischium and also along the back of the thigh to about its reduced third, wherein it divides into 2 large branches, the tibial and also common fibular (peroneal) nerves (see the picture below). This division may take ar at any suggest between the sacral plexus and the lower 3rd of the thigh.


The sciatic nerve supplies the hamstring muscle and all of the muscles and also skin the the leg and also foot via that 2 branches, the tibial and also common fibular nerves.


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Sacral plexus, posterior view of reduced extremity.

Tibial Nerve

The tibial nerve is the larger of the 2 terminal branches of the sciatic nerve. It arises from the anterior branches of the fourth and fifth lumbar and first, second, and third sacral nerve roots. This nerve descends along the back of the thigh and also through the center of the popliteal fossa come the lower component of the popliteus muscle, whereby it passes with the popliteal artery beneath the arch the the soleus. The tibial nerve climate runs along the ago of the leg v the posterior tibial ship to the interval in between the medial malleolus and also the heel, where it divides beneath the flexor retinaculum (laciniate ligament) right into the medial and also lateral plantar nerves.


In the thigh, it is overlapped through the hamstring muscles above and climate becomes much more superficial and also lies lateral to, and also some distance from, the popliteal vessels. The contrary the knee joint, the tibial nerve is in nearby relation through these vessels, and also crosses come the medial side of the artery. In the leg, it is covered in the upper part of its food by the muscles of the calf; lower down, it is extended by the skin, the superficial and deep fascia. The tibial nerve is placed on the deep muscles and lies at very first to the medial next of the posterior tibial artery but soon the cross that vessel and descends on its lateral next as much as the ankle. In the lower 3rd of the leg, it runs parallel v the medial margin of the tendo calcaneus.


Articular branches supply the i know good joint. Muscular branches in the thigh it is provided the semitendinosus, semimembranosus, lengthy head of the biceps femoris, and the ischiocondylar part of the adductor magnus muscles


Articular branches, usually 3 in number, likewise supply the knee joint; 2 of this accompany the superior and inferior medial genicular arteries, and a 3rd supplies the middle genicular artery. Just above the bifurcation that the nerve, an articular branch is given off come the fish eye joint.


Muscular branches, 4-5 in number, arise indigenous the nerve as it lies in between the 2 top of the gastrocnemius muscle and also supply the muscle and also the plantaris, soleus, and also popliteus muscles. The branch because that the popliteus turns roughly the lower border that the popliteus and also is distributed to the deep surface of the muscle. Lower down, muscular branches arise separately or by a typical trunk and also supply the soleus, tibialis posterior, flexor digitorum longus, and also flexor hallucis longus. The branch to the flexor hallucis longus accompanies the fibular (peroneal) artery, whereas the to the soleus beginning the deep surface ar of the muscle.


The medial sural cutaneous nerve descends between the 2 top of the gastrocnemius, and, in ~ the level the the middle of the earlier of the leg, pierces the deep fascia and unites through the communicating ramus the the lateral sural cutaneous branch that the common fibular (peroneal) nerve to type the sural nerve.


The sural nerve is formed by the junction the the medial sural cutaneous v the fibular (peroneal) connecting branch. It passes downward near the lateral margin the the tendo calcaneus, lie close to the little saphenous vein, come the space between the lateral malleolus and the calcaneus. The sural nerve runs forward listed below the lateral malleolus and continues together the lateral dorsal cutaneous nerve along the lateral side of the foot and little toe, communicating on the dorsum of the foot through the intermediate dorsal cutaneous nerve, a branch the the superficial fibular (peroneal).


Medial calcaneal branches perforate the flexor retinaculum (laciniate ligament) and also supply the skin of the heel and medial next of the single of the foot.


The medial plantar nerve is the larger of the 2 terminal departments of the tibial nerve and accompanies the medial plantar artery. Native its beginning under the flexor retinaculum (laciniate ligament), the medial plantar nerve overcome under covering of the abductor hallucis and appears between this muscle and also the flexor digitorum brevis. It provides off a proper plantar digital nerve and also divides the contrary the bases of the metatarsal bones right into 3 typical plantar digital nerves.


The cutaneous branches pierce the plantar aponeurosis in between the abductor hallucis and also the flexor digitorum brevis and also are distributed to the skin that the sole of the foot


The muscular branches it is provided the abductor hallucis, the flexor digitorum brevis, the flexor hallucis brevis, and the very first lumbrical; those giving the abductor hallucis and flexor digitorum brevis arise from the tribe of the nerve near its origin and also enter the deep surface of the muscles; the branch that the flexor hallucis brevis springs indigenous the suitable plantar digital nerve come the medial side of the good toe, and that offering the an initial lumbrical native the an initial common plantar digital nerve


The proper plantar digital nerve of the an excellent toe gives the flexor hallucis brevis and also the skin top top the medial side of the good toe; each suitable plantar digital nerve offers off cutaneous and articular filaments; the opposite the last phalanx, this digital nerves send upward a dorsal branch, which provides the structures approximately the nail; the continuation of this nerves are distributed to the sphere of the toe


The 3 common plantar digital nerves pass between the divisions of the plantar aponeurosis, and each splits into 2 suitable plantar digital nerves; those that the very first common plantar digital nerve it is provided the adjacent sides of the an excellent and second toes, conversely, those that the 2nd supply the surrounding sides that the second and 3rd toes, and also those the the third an in similar way supply the surrounding sides that the 3rd and 4th toes; the third common plantar digital nerve obtain a communicating branch indigenous the lateral plantar nerve, vice versa, the very first gives a twig to the very first lumbrical muscle


The lateral plantar nerve supplies the skin of the fifth toe and also lateral fifty percent of the 4th toe, as well as most of the deep muscles. That passes through the lateral plantar artery to the lateral side of the foot, lying between the flexor digitorum brevis and also quadratus plantae and, in the interval between the previous muscle and also the abductor number minimi quinti, divides into a superficial and a deep branch. Before its division, it gives the quadratus plantae and abductor number minimi quinti.

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The superficial branch that the lateral plantar nerve splits into a proper and also a usual plantar digital nerve; the proper plantar digital nerve provides the lateral next of the tiny toe, the flexor digit minimi (quinti) brevis, and the 2 interossei the the 4th intermetatarsal space. The common plantar digital nerve communicates v the 3rd common plantar digital branch that the medial plantar nerve and divides into 2 proper plantar digital nerves the supply the adjoining sides of the fourth and also fifth toes.