The posterior division dorsal ramus is labeled at the top right. A nerve plexus is a network of intersecting nerves; multiple nerve plexuses exist in the body.
Nerve plexuses are 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 cervical plexus is formed by the ventral rami of the upper four cervical nerves and the upper part of fifth cervical ventral ramus. The network of rami is located deep within the neck.
The brachial plexus is formed by the ventral rami of C5—C8 and the T1 spinal nerves, and lower and upper halves of the C4 and T2 spinal nerves. The plexus extends toward the armpit axilla. The lumbar plexus is formed by the ventral rami of L1—L5 spinal nerves with a contribution of T12 form the lumbar plexus.
This plexus lies within the psoas major muscle. The sacral plexus is formed by the ventral rami of L4-S3, with parts of the L4 and S4 spinal nerves. It is located on the posterior wall of the pelvic cavity. The coccygeal plexus serves a small region over the coccyx and originates from S4, S5, and Co1 spinal nerves.
It is interconnected with the lower part of sacral plexus. Brachial plexus : Cervical C5—C8 and thoracic T1 nerves comprise the brachial plexus, which is a nerve plexus that provides sensory and motor function to the shoulders and upper limbs.
Lumbar plexus : The lumbar plexus is comprised of the ventral rami of the lumbar spinal nerves L1—L5 and a contribution from thoracic nerve T The posterior green and anterior yellow divisions of the lumbar plexus are shown in the diagram.
The intercostal nerves are part of the somatic nervous system and arise from anterior divisions rami anteriores, ventral divisions of the thoracic spinal nerves T1 to T The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum.
Intercostal nerves : An image of the intercostal brachial nerves. They differ from the anterior divisions of the other spinal nerves in that each pursues an independent course without plexus formation. These are limited in their distribution to the parietes wall of the thorax. The anterior divisions of the second, third, fourth, fifth, and sixth thoracic nerves, and the small branch from the first thoracic, are confined to the walls of the thorax and are named thoracic intercostal nerves.
Near the sternum, they cross in front of the internal mammary artery and transversus thoracis muscle, pierce the intercostales interni, the anterior intercostal membranes, and pectoralis major, and supply the integument of the front of the thorax and over the mamma, forming the anterior cutaneous branches of the thorax.
The branch from the second nerve unites with the anterior supraclavicular nerves of the cervical plexus. The seventh intercostal nerve terminates at the xyphoid process, at the lower end of the sternum. The anterior divisions of the seventh, eighth, ninth, tenth, and eleventh thoracic intercostal nerves are continued anteriorly from the intercostal spaces into the abdominal wall; hence they are named thoraco-abdominal nerves or thoracicoabdominal intercostal nerves.
Unlike the nerves from the autonomic nervous system that innervate the visceral pleura of the thoracic cavity, the intercostal nerves arise from the somatic nervous system. This enables them to control the contraction of muscles, as well as provide specific sensory information regarding the skin and parietal pleura.
This explains why damage to the internal wall of the thoracic cavity can be felt as a sharp pain localized in the injured region. Damage to the visceral pleura is experienced as an unlocalized ache. A dermatome is an area of skin that is supplied by a single spinal nerve, and a myotome is a group of muscles that a single spinal nerve root innervates. A dermatome is an area of skin that is supplied by a single spinal nerve. There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves and five sacral nerves.
Each of these nerves relays sensation, including pain, from a particular region of the skin to the brain. Dermatomes : Dermatomes are areas of skin supplied by sensory neurons that arise from a spinal nerve ganglion. Dermatomes and the associated major cutaneous nerves are shown here in a ventral view. Along the thorax and abdomen, the dermatomes are like a stack of discs, with each section supplied by a different spinal nerve. Along the arms and the legs, the pattern is different.
The dermatomes run longitudinally along the limbs, so that each half of the limb has a different dermatome. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints. Dermatomes have clinical significance, especially in the diagnosis of certain diseases.
Symptoms that follow a dermatome, such as pain or a rash, may indicate a pathology that involves the related nerve root. Examples include dysfunction of the spine or a viral infection. Viruses that remain dormant in nerve ganglia, such as the varicella zoster virus that causes both chickenpox and shingles, often cause either pain, rash, or both in a pattern defined by a dermatome. Shingles rash : The shingles rash appears across a dermatome.
In this patient, one of the dermatomes in the arm is affected, restricting the rash to the length of the back of the arm. Shingles is one of the only diseases that causes a rash in a dermatomal pattern, and as such, this is its defining symptom. The rash of shingles is almost always restricted to a specific dermatome, such as on the chest, leg, or arm caused by the residual varicella zoster virus infection of the nerve that supplies that area of skin. Shingles typically appears years or decades after recovery from chickenpox.
A myotome is the group of muscles that a single spinal nerve root innervates. The myotome is the motor equivalent of a dermatome. The testing of myotomes provides the clinician with information about the level in the spine where a lesion may be present.
During testing, the clinician looks for muscle weakness of a particular group of muscles. Results may indicate lesions to the spinal cord nerve root, or intervertebral disc herniation that presses on the spinal nerve roots.
The peripheral nervous system PNS consists of the nerves and ganglia outside of the brain and spinal cord. Unlike the CNS, the PNS is not protected by the bones of the spine and skull, or by the blood —brain barrier, leaving it exposed to toxins and mechanical injuries. The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system.
Spinal nerve : This diagram indicates the formation of a typical spinal nerve from the dorsal and ventral roots. Numbers indicate the types of nerve fibers: 1 somatic efferent, 2 somatic afferent, 3—5 sympathetic efferent, 6—7 sympathetic afferent. The peripheral nervous system includes 12 cranial nerves and 31 pairs of spinal nerves that provide communication from the CNS to the rest of the body by nerve impulses to regulate the functions of the human body. The term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body.
Each pair of spinal nerves roughly correspond to a segment of the vertebral column: 8 cervical spinal nerve pairs C1—C8 , 12 thoracic pairs T1—T12 , 5 lumbar pairs L1—L5 , 5 sacral pairs S1—S5 , and 1 coccygeal pair.
It is probably caused by an autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues.
What triggers autoimmune disorders is not known. Symptoms vary depending on This disorder occurs primarily in men. It typically occurs in young adults but can occur at any age. Malfunction of the brachial plexus causes pain, weakness, and loss of sensation in an arm. All or part of the arm such as the forearm or biceps may be affected. If the cause is an injury, recovery tends to occur slowly, over several months. Some severe injuries cause permanent weakness.
Acute brachial neuritis causes severe pain in the upper arms and shoulders. Usually, the arm becomes weak and reflexes are impaired as the pain resolves.
Weakness develops within 3 to 10 days. Then people typically regain their strength over the next few months. Malfunction of the lumbosacral plexus causes pain in the lower back and leg as well as weakness and loss of sensation in all or part of a leg such as the foot or calf.
Recovery depends on the cause. Doctors suspect that a plexus is involved when symptoms are located in a part of the body supplied by a specific plexus. The location of the symptoms indicates which plexus is affected. Electromyography and nerve conduction studies Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography EEG is a simple, painless procedure in which Magnetic resonance imaging MRI or computed tomography CT can help determine whether a cancer, another mass, or an injury is causing the plexus disorder.
Treatment of a plexus disorder depends on the cause. Cancer near the plexus may be treated with radiation therapy, chemotherapy, or both. Occasionally, a cancer or another mass that is damaging the plexus must be removed surgically. If diabetes Treatment Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar glucose levels to be abnormally high.
Urination and thirst are Then, tiny electrical signals are passed between the needles. The speed at which those signals travel is measured and compared to accepted normal values. A slowing of the electrical signal indicates that a specific nerve is damaged. Once that nerve of a specific plexus is identified, treatment can be properly directed. Sometimes other diagnostic tests, like a magnetic resonance imaging MRI or computerized tomography CT scan , are performed to look for damage to a nerve plexus.
A minor injury to a plexus usually requires no treatment at all. Symptoms tend to be mild and temporary, and usually go away with the passage of time. Some plexus injuries may require more intensive treatments for you to recover. Treatment for a ruptured nerve may involve surgery to repair the damage. Surgery may involve a nerve transfer, neurolysis freeing nerves from scar tissue , or a nerve graft.
These surgeries are considered most effective when performed within six months of the injury, so time is of the essence. After a nerve plexus injury, you may benefit from working with a physical therapist or occupational therapist.
They can assess your condition and prescribe specific treatments to maintain muscle function and joint range of motion. Your body is a complex series of muscles, bones, tendons, and nerves. When nerves exit your spinal canal, they are sorted and organized in a plexus.
This plexus serves to keep nerve signals organized and to create a system where your nerves are protected from injury. A disruption of one nerve may be mitigated by its neighboring nerves. A plexus injury may cause numbness, tingling, or loss of movement.
Severe plexus injuries may require the care of a qualified physician to help you fully recover. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Do not waste your time: straight to magnetic resonance imaging for pediatric burners and stingers.
Am J Emerg Med. Timing of surgery in traumatic brachial plexus injury: a systematic review. J Neurosurg. Your Privacy Rights. To change or withdraw your consent choices for VerywellHealth. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page.
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