| Lumbosacral trunk | |
|---|---|
 Plan of lumbar plexus. | |
 Dissection of side wall of pelvis showing sacral and pudendal plexuses. | |
| Details | |
| From | L4-L5 |
| Identifiers | |
| Latin | truncus lumbosacralis |
| TA98 | A14.2.07.026 |
| TA2 | 6504 |
| FMA | 65535 |
| Anatomical terms of neuroanatomy | |
The lumbosacral trunk is nervous tissue that connects the lumbar plexus with the sacral plexus. It is formed by the union of parts of the fourth and fifth lumbar nerves and descends to join the sacral plexus.
The lumbosacral trunk is formed by the union of the entire anterior ramus of lumbar nerve L5 and a part of L4[ clarification needed ]. [1] [2] [3] L4 first issues its branches to the lumbar plexus, then emerges from the medial border of the psoas muscle [3] to unite with the anterior ramus of L5 just superior to the pelvic brim to form the thick, cord-like trunk which [4] crosses the pelvic brim (medial to the obturator nerve) [3] to descend upon the anterior surface of the ala of sacrum before joining the sacral plexus. [4]
Like the sacral nerves, the lumbosacral trunks splits into an anterior division and a posterior division before recombining to form nerves for the flexor and extensor compartments of the lower limb. [3]
The lumbosacral trunk may be compressed by the fetal head during the second stage of labour. [5] This causes some muscle weakness in the legs. [5] A full recovery is usually expected. [5]
The human leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.
The sciatic nerve, also called the ischiadic nerve, is a large nerve in humans and other vertebrate animals which is the largest branch of the sacral plexus and runs alongside the hip joint 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. The sciatic nerve has no cutaneous branches for the thigh. This nerve provides the connection to the nervous system for the skin of the lateral leg and the whole foot, 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 fibers from both the anterior and posterior divisions of the lumbosacral plexus.
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.
A nerve plexus is a plexus 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 plexuses, except in the thoracic region, as well as other forms of autonomic plexuses, many of which are a part of the enteric nervous system. The nerves that arise from the plexuses have both sensory and motor functions. These functions include muscle contraction, the maintenance of body coordination and control, and the reaction to sensations such as heat, cold, pain, and pressure. There are several plexuses in the body, including:
In human anatomy, the sacral plexus is a nerve plexus which provides motor and sensory nerves for the posterior thigh, most of the lower leg and foot, and part of the pelvis. It is part of the lumbosacral plexus and emerges from the lumbar vertebrae and sacral vertebrae (L4-S4). A sacral plexopathy 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.
The internal iliac artery is the main artery of the pelvis.
The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee. It is the largest branch of the lumbar plexus.
The inferior gluteal nerve is the main motor neuron that innervates the gluteus maximus muscle. It is responsible for the movement of the gluteus maximus in activities requiring the hip to extend the thigh, such as climbing stairs. Injury to this nerve is rare but often occurs as a complication of posterior approach to the hip during hip replacement. When damaged, one would develop gluteus maximus lurch, which is a gait abnormality which causes the individual to 'lurch' backwards to compensate lack in hip extension.
The lumbar plexus is a web of nerves 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 subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip joint and mainly support the anterior part of the thigh.
The iliohypogastric nerve is a nerve that originates from the lumbar plexus that supplies sensation to skin over the lateral gluteal and hypogastric regions and motor to the internal oblique muscles and transverse abdominal muscles.
The lumbar nerves are the five pairs of spinal nerves emerging from the lumbar vertebrae. They are divided into posterior and anterior divisions.
The obturator nerve in human anatomy arises from the ventral divisions of the second, third, and fourth lumbar nerves in the lumbar plexus; the branch from the third is the largest, while that from the second is often very small.
The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet. Its lower boundary is the pelvic floor.
The anterior divisions of the lumbar nerves, sacral nerves, and coccygeal nerve form the lumbosacral plexus, the first lumbar nerve being frequently joined by a branch from the twelfth thoracic. For descriptive purposes this plexus is usually divided into three parts:
The nerve to obturator internus, also known as the obturator internus nerve, is a nerve that innervates the obturator internus and gemellus superior muscles.
The hypogastric nerves are the continuation of the superior hypogastric plexus that descend into the pelvis anterior the sacrum and become the inferior hypogastric plexuses on either side of pelvic organs. The hypogastric nerves serve as a pathway for autonomic fibers to communicate between the lower abdomen and pelvis.
The ventral ramus is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami.
The following outline is provided as an overview of and topical guide to human anatomy:
The pelvis is the lower part of the trunk, between the abdomen and the thighs, together with its embedded skeleton.
