| Sacral spinal nerve | |
|---|---|
 The plan of the lumbosacral plexus | |
| Details | |
| Identifiers | |
| Latin | nervi spinalis |
| FMA | 6423 |
| Anatomical terminology | |
The sacral spinal nerve 1 (S1) is a spinal nerve of the sacral segment. [1]
It originates from the spinal column from below the 1st body of the sacrum.
S1 supplies many muscles, either directly or through nerves originating from S1. They are not innervated with S1 as single origin, but partly by S1 and partly by other spinal nerves. The muscles are:
Pronator quadratus is a square-shaped muscle on the distal forearm that acts to pronate the hand.
The sciatic nerve, also called the ischiadic nerve, is a large nerve in humans and other vertebrate animals. It 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 fibres 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.
The piriformis muscle is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group.
The lateral rotator group is a group of six small muscles of the hip which all externally (laterally) rotate the femur in the hip joint. It consists of the following muscles: piriformis, gemellus superior, obturator internus, gemellus inferior, quadratus femoris and the obturator externus.
The posterior cutaneous nerve of the thigh is a sensory nerve of the thigh. It is a branch of the sacral plexus. It supplies the skin of the posterior surface of the thigh, leg, buttock, and also the perineum.
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 superior gluteal nerve is a mixed nerve of the sacral plexus that originates in the pelvis. It provides motor innervation to the gluteus medius, gluteus minimus, tensor fasciae latae, and piriformis muscles; it also has a cutaneous branch.
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 perforating cutaneous nerve is a cutaneous nerve of the sacral plexus that provides sensory innervation to the skin of the buttocks.
The erector spinae or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes to maintain stable posture standing or sitting.
The inferior gluteal artery is a terminal branch of the anterior trunk of the internal iliac artery. It exits the pelvis through the greater sciatic foramen. It is distributed chiefly to the buttock and the back of the thigh.
The nerve to obturator internus is a mixed nerve providing motor innervation to the obturator internus muscle and gemellus superior muscle, and sensory innervation to the hip joint. It is a branch of the sacral plexus. It is one of the group of deep gluteal nerves.
The nerve to quadratus femoris is a nerve of the sacral plexus that provides motor innervation to the quadratus femoris muscle and gemellus inferior muscle, and an articular branch to the hip joint. The nerve leaves the pelvis through the greater sciatic foramen.
A nerve root is the initial segment of a nerve leaving the central nervous system. Nerve roots can be classified as:
The following outline is provided as an overview of and topical guide to human anatomy:
The sacral spinal nerve 4 (S4) is a spinal nerve of the sacral segment.
The sacral spinal nerve 3 (S3) is a spinal nerve of the sacral segment.
The sacral spinal nerve 2 (S2) is a spinal nerve of the sacral segment.
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