The sacral plexus (Latin name - plexus sacralis) is formed by the 4th and 5th abdominal branches of the lumbar and spinal sacral nerves. They are formed into a bundle, which is called the lumbosacral trunk (in Latin - truncus lumbosacralis) and is part of the plexus sacralis. This plexus includes fibers from the nodes of the lower lumbar and sacral sympathetic trunk. The branches of the sacral plexus are located on the piriformis muscle (Latin name - m. piriformis) in the small pelvis and converge to the holes located above and below the piriformis muscle. Through the holes above, the branches go to the back of the pelvis.
Plexus with short mixed branches
The spine is functionally important for a person. Due to the lumbar vertebrae, lordosis is formed. This part of the spine experiences the greatest load.
The sacral plexus is located anterior to the transverse processes of the lumbar vertebrae. Its anatomy is unique and has been studied for a long time.
Muscular branches
Muscular branches (Latin name - rr. musculares) are formed by fibers L4 and L5, and alsoS1 and S2, supply nerves to the pelvic area m. piriformis, obturatorius internus. After passing through the hole under the piriformis muscle, they connect the quadriceps femoral muscle (m. quadratus femoris) with the central nervous system. These soft tissues contain receptors for other fibers. For example, femoral nerve tissue.
Upper Gluteus
The superior gluteal nerve (in Latin - n.gluteus superior) is formed by fibers L2 - L5 and S 1 and is represented by a short barrel. It follows through the supra-pear opening from the small pelvis to the dorsum of the pelvis. At the same time, it combines into a joint bundle with the arteries and vein of the same name. The nerve is divided into 3 branches, which supply sensory fibers to the small and medium muscles of the buttocks and thighs. Receptors are located in small, medium muscle tissue and the connective sheath. The sacral plexus nerves are important.
Lower Gluteus
Inferior gluteal nerve (Latin name - n.gluteus inferior), which is formed by fibers L5 and S1-S 2, is represented by a short trunk passing to the back surface of the pelvis through a slit-like gap in the lower part of the large paired opening of the posterior inferior part of the pelvic wall, like blood vessels. The psoas major muscle is supplied with nerves. Receptors are located both in the hip joint and in the large muscle of the buttocks. There is a connection of sensory nerve fibers and motor fibers. They then move together to the nuclei of the spinal cord.
Sacral plexus and long branches
Muscular branches radiate from all anterior branches that form the plexus (before they join). They are responsible for the innervation of the psoas minor and major muscles, the square muscle and the transverse lateral psoas muscles. Damage to branches can lead to serious consequences.
Nerve of the lumbar plexus, located behind (Latin name - n. cutaneus femoris posterior), thin, long and sensitive. The receptors are located within the skin and the connective sheath of the thigh of the back, the fossa of the knee joint, in the perineum and at the bottom of the gluteal muscle. The nerve endings and the trunk are located under the adipose tissue on the connective tissue membrane of the thigh. Then in the middle in the crease of the buttocks at the lower edge (m. Gluteus maximus) the fiber passes through the connective tissue membrane. Here, hiding behind the large gluteal nerve, it accompanies the sciatic nerve. Passes through the hole under the piriformis muscle into the deepening of the pelvis and forms the posterior roots L1- L3.
The roots L4- L5 take part in the formation of the sciatic nerve (in Latin - n. ischiadicus). S1- S3, is the thickest and longest fiber in the human body, it is also called mixed. The abdominal branches emerge from the intervertebral foramina. The nerve, which is formed on the wall near the paired opening in the posterior inferior part of the pelvic wall, passes through the slit-likethe gap in the lower part of the paired opening from the deepening of the pelvis and lies in the cavity between the ischial tubercle and the trochanter of the tubular thigh bone on the thigh muscle, which has a square shape, under the gluteal muscle. Here is the femoral nerve.
Sciatic nerve
This section of the system is located in the dorsal part of the thigh on the medial muscle and the long head of the biceps femoris. It goes down between the semimembranosus and semitendinosus muscles. From the sciatic nerve in the thigh region, moving branches depart, the long head of the biceps, semitendinosus and semimembranosus muscles of the thigh. The sciatic nerve enters at the upper corner of the fossa, located under the knee, or into the opening of the thigh. Here it divides into the tibial and peroneal nerves. Consider the further structure of the system.
The tibial nerve (in Latin - n. tibialis) is located at the top of the popliteal fossa between the fascia and the popliteal vessels, continuing its plexus between the gastrocnemius muscles into the ankle-popliteal canal (the Latin name is canalis cruropopliteus). Below on the lower leg, it is located between the long soft tissues of the lower leg of the posterior group. The tibial nerve in the foot divides into the median and lateral plantar nerve endings.
Tibular fiber branches
Muscular mixed branches have the Latin name rr. musculares). The first group departs where the tibial nerve passes through the ankle-popliteal canal. They are used to make a sensitive connection of the gastrocnemius, soleus, plantar muscles. Secondthe group departs at the bottom of the lower leg. They are designed to provide a nerve connection to the posterior tibial, long leg muscle of the posterior group. All these tissues have receptors from which smaller fibers extend. They go along the muscle branches to the tibial nerve.
The mixed median plantar nerve (Latin name - n. plantaris medialis) is located on the middle edge of the sole in the groove between the muscle that abducts the first toe and the muscle of the plantar part of the foot. It provides motor cells that respond to any stimulus. These muscles contain receptors associated with sensory fibers that are involved in the formation of the median plantar nerve.
On the middle part of the foot, a lateral branch departs from the median plantar fiber (in Latin - r. lateralis) to provide sensitive cells 1 and 2 of the worm-like muscles. The sensitive part of the lateral branch has receptors in the skin of the first, second and third fingers, the lateral half of the fourth finger and in the palmar interosseous muscles. The fibers take part in the formation of nerves on the sole, which are connected to 3 common plantar nerves. They, in turn, find a connection with the lateral branch. In the direction from the skin receptors of the middle surface of the first toe, the tibial nerve is directed. It connects to the medial branch of the median plantar fiber, located on the side of the muscle that leads away the big toe. But this is not all the features of the structure. What other nerves does the lumbosacral region contain?
Lateral plantar
The lateral mixed plantar nerve (Latin name - n. plantaris lateralis) is located on the lateral edge of the foot in the groove between the muscle of the plantar part and the square foot muscle, then goes into the groove, which is formed by the muscles of the 5th finger and the muscle of the foot. Its deep branch at the level of the metatarsal bends in the middle. Here it provides nerve cells to the muscles of the fifth finger (abductor fifth finger, short flexor, adductor first finger, third and fourth thin short muscle between the tendons of the long flexor of the fingers and interosseous muscles). Receptors are located in the skin and subcutaneous adipose tissue. You can find them in the area of the 4th and 5th fingers. It is from them that the nerves come, connecting into a large nerve going to the upper branch of the lateral nerve of the sole. They form the lumbosacral plexus.
Medium Gastrocnemius
The median sural nerve has the Latin name n. cutaneus surae medialis. Its endings are located on the dorsum of the lower leg from the medial side. At the same time, they alternate with the receptors of the femoral nerve. The fibers, reaching the bottom of the popliteal fossa, pierce the fascia of the lower leg. Here they enter the tibial nerve.
There are other fragments of this system. For example, the sural nerve with the Latin name n. suralis. It is sensitive and contains endings in the skin and subcutaneous adipose tissue on the back of the leg, heel and side of the foot. It is from them that the dorsal nerve begins. Fibers, reaching the lateral ankle,carry out the transition to the main tibial nerve. Sensitive tissues are located in the subcutaneous tissue in the lower third of the leg from the side. Then they are sent along two trunks of nerves: one - along the tibial nerve, the other - along the common peroneal nerve. It is worth listing other features of the system. What nerves does the lumbosacral region have?
Sensitive fibers of the lower leg
The nerve of the lower leg is also sensitive. It is located between the bones (Latin name - n. interosseus cruris). The endings are located in the membrane between the bones, in the areas above the bones of the lower leg and in the ankle joint. At the same time, it connects with other fibers. It goes along the membrane and enters the tibial nerve in the place where there is a hole in the membrane between the bones.
Articular branches (in Latin - rr. articulares) are formed from the ends of the capsule of the ankle and knee joints. They join with the tibial nerve as it passes near them.
Lesser tibial nerve (Latin name - n. fibularis communis) is mixed, separated from the nerve of the sciatic in the region of the thigh. It is located on the lateral side of the fossa under the knee and the head of the fibula. Its sensitive fiber bypasses from the back. In this case, the nerve is located between the neck of the fibula and the beginning of the long peroneal muscle.
What else does the sacral plexus include? This will be discussed further.
Branches of the peroneal nerve
Lateral sural nerve (Latin name - n. cutaneus surae lateralis)very sensitive. The endings are in the skin, fiber and connective tissue membrane of the posterolateral part of the lower leg. Fibers with high sensitivity go under the connecting sheath. It forms a case for the lower leg. Here the nerve connects to the fibers of the tibial nerve. In the hole under the knee, they come out from under the connective sheath. At this point, it merges with the small tibial nerve.
Articular branches (Latin name - rr. articulares) are sensitive and have endings in the capsule between the tibia and knee joint. Branches from this section are short. Especially those that are located between the tibial joint and have an entrance to the small nerve. Fusion occurs when it is close to the head of the fibula. The nerve branches from the knee joint are thick. They enter the system in the corner of the popliteal fossa. What else is included in the sacrococcygeal plexus?
Branches of muscles (in Latin - rr. musculares) - motor nerves of short length. Provide sensitive cells to the head of the biceps femoral muscle.
The superficial peroneal nerve (Latin name - n. fibularis superficialis) is mixed and widely provided with nerve cells. Receptors are located on the foot in the skin of the dorsal surface and interdigital spaces of the third, fourth and median surface of the fifth toe. From them, the posterior nerves are formed, which are combined into an intermediate dorsal cutaneous nerve of the foot.
So, we have examined the anatomy of the sacral plexus in detail.
