"nerve roots result in typical patterns of neurologic defects (muscle weakness, abnormal sensation, changes in reflexes) that allow localization of the responsible lesion. There are several procedures used in sacral nerve stimulation for the treatment of various related disorders. Sciatica is generally caused by the compression of lumbar nerves L4, or L5 or sacral nerves S1, S2, or S3, or by compression of the sciatic nerve itself. Spinal nerve 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"
"Vagus nerve The vagus nerve ( ), historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with parasympathetic control of the heart, lungs, and digestive tract. The vagus nerves are paired but are normally referred to in the singular. It is the longest nerve of the autonomic nervous system in the human body. Upon leaving the medulla oblongata between the pyramid and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein down to the"
"was also historically called the ""pneumogastric"" nerve since it innervates both the lungs and the stomach. Vagus nerve The vagus nerve ( ), historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with parasympathetic control of the heart, lungs, and digestive tract. The vagus nerves are paired but are normally referred to in the singular. It is the longest nerve of the autonomic nervous system in the human body. Upon leaving the medulla oblongata between the pyramid and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into"
"have axons up to a meter in length in humans. The longest axon in the human body belongs to the Sciatic Nerve and runs from the great toe to the base of the spinal cord. These are archetypal examples of neural pathways. Neural pathways in the basal ganglia in the cortico-basal ganglia-thalamo-cortical loop, are seen as controlling different aspects of behaviour. This regulation is enabled by the dopamine pathways. It has been proposed that the dopamine system of pathways is the overall organiser of the neural pathways that are seen to be parallels of the dopamine pathways. Dopamine is provided"
"sciatic nerve, which is the longest and widest nerve in the human body, beginning in the lower back and running through the buttocks all the way to the lower limb, is a frequent target for low kicks. The most common defense against a low kick is known as ""checking"", where the leg is bent and brought up to protect the thigh. This causes the kicker to slam their shin into the defending fighters' shin or knee, causing pain and damage to the offender. In some instances, a well executed check of a low kick can break the leg of the"
"Saphenous nerve The saphenous nerve (long or internal saphenous nerve) is the largest cutaneous branch of the femoral nerve. It is a strictly sensory nerve, and has no motor function. It approaches the femoral artery where this vessel passes beneath the sartorius, and lies in front of the artery, behind the aponeurotic covering of the adductor canal, as far as the opening in the lower part of the Adductor magnus. Here it diverges from the artery, and emerges from behind the lower edge of the aponeurotic covering of the canal; it descends vertically along the medial side of the knee"
"Axillary nerve The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus (upper trunk, posterior division, posterior cord) at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein. The nerve lies at first behind the axillary artery, and in front of the subscapularis, and passes downward to the lower border of that muscle. It then winds backward, in company with the posterior humeral circumflex artery, through a quadrangular space"
"Ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body (meaning unprotected by muscle or bone), so injury is common. This nerve is directly connected to the little finger, and the adjacent half of the ring finger, innervating the palmar aspect of these fingers, including both front and back of the tips, perhaps as far back as the fingernail beds. This nerve can cause an electric shock-like sensation"
"the brain and generate thousands of synaptic terminals. A bundle of axons make a nerve tract in the central nervous system, and a fascicle in the peripheral nervous system. In placental mammals the largest white matter tract in the brain is the corpus callosum, formed of some 20 million axons in the human brain. Axons are the primary transmission lines of the nervous system, and as bundles they form nerves. Some axons can extend up to one meter or more while others extend as little as one millimeter. The longest axons in the human body are those of the sciatic"
"Median nerve The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus. The median nerve originates from the lateral and medial cords of the brachial plexus, and has contributions from ventral roots of C5-C6 (lateral cord) and C8 and T1 (medial cord). The median nerve is the only nerve that passes through the carpal tunnel. Carpal tunnel syndrome is the disability that results from the median nerve being pressed in the carpal tunnel. The median nerve arises from the branches from lateral"
"Femoral nerve 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. Femoral nerve is the major nerve supplying the anterior compartment of the thigh. It is the largest branch of the lumbar plexus, and arises from the dorsal divisions of the ventral rami of the second, third, and fourth lumbar nerves (L2, L3, and L4). The nerve enters the femoral triangle by passing beneath the inguinal ligament, just lateral to the femoral artery. In the thigh, the nerve lies in a groove between"
"Spinal nerve 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. Each spinal nerve is"
"base and form a nerve trunk, which, in humans, is approximately one inch long. This travels in parallel with the vestibular nerves through the internal auditory canal, through which it connects to the brainstem. There, its fibers synapse with the cell bodies of the cochlear nucleus. In mammals, cochlear nerve fibers are classified as either type I or type II. In mammals, the axons from each cochlear nerve terminate in the cochlear nuclear complex that is ipsilaterally located in the medulla of the brainstem. The cochlear nucleus is the first 'relay station' of the central auditory system and receives mainly"
"""efferent"" correspond to the prefixes ""ad-"" (to, toward) and ""ex-"" (out of). There are 43 segments of nerves in the human body. With each segment, there is a pair of sensory and motor nerves. In the body, 31 segments of nerves are in the spinal cord and 12 are in the brain stem. Besides these, thousands of association nerves are also present in the body. Thus the somatic nervous system consists of two parts: The somatic nervous system controls all voluntary muscular systems within the body, and the process of voluntary reflex arcs. The basic route of nerve signals within"
"nervous system (PNS), although on a structural level the olfactory (I), optic (II), and trigeminal (V) nerves are more accurately considered part of the central nervous system (CNS). Most typically, humans are considered to have twelve pairs of cranial nerves (I–XII), with the terminal nerve (0) more recently canonized. They are: the olfactory nerve (I), the optic nerve (II), oculomotor nerve (III), trochlear nerve (IV), trigeminal nerve (V), abducens nerve (VI), facial nerve (VII), vestibulocochlear nerve (VIII), glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI), and hypoglossal nerve (XII). Cranial nerves are generally named according to their structure or"
"of left phrenic nerve has not been significantly linked to reduced pulmonary vital capacity. Phrenic nerve The phrenic nerve is a nerve that originates in the neck (C3-C5) and passes down between the lung and heart to reach the diaphragm. It is important for breathing, as it passes motor information to the diaphragm and receives sensory information from it. There are two phrenic nerves, a left and a right one. The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 5th and 3rd cervical nerves (C3-C5) in humans. Thus, the phrenic nerve receives innervation"
"components; however, dendrites and axons often act in ways contrary to their so-called main function. Axons and dendrites in the central nervous system are typically only about one micrometer thick, while some in the peripheral nervous system are much thicker. The soma is usually about 10–25 micrometers in diameter and often is not much larger than the cell nucleus it contains. The longest axon of a human motor neuron can be over a meter long, reaching from the base of the spine to the toes. Sensory neurons can have axons that run from the toes to the posterior column of"
"the coccyx. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. The length of the spinal cord is much shorter than the length of the bony spinal column. The human spinal cord extends from the foramen magnum and continues through to the conus medullaris near the second lumbar vertebra, terminating in a fibrous extension known as the filum terminale. It is about 45 cm (18 in) long in men and around 43 cm (17 in) in women, ovoid-shaped, and is enlarged in the cervical and lumbar regions. The cervical enlargement, located from C3"
"bundles of the long fibers or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called ""motor"" or ""efferent"" nerves, while those nerves that transmit information from the body to the CNS are called ""sensory"" or ""afferent"". Spinal nerves serve both functions and are called ""mixed"" nerves. The PNS is divided into three separate subsystems, the somatic, autonomic, and enteric nervous systems. Somatic nerves mediate voluntary movement. The autonomic nervous system is further subdivided into the sympathetic and the parasympathetic nervous systems. The sympathetic nervous system is activated in"
"Cranial nerves Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), in contrast to spinal nerves (which emerge from segments of the spinal cord). 10 of the cranial nerves originate in the brainstem. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck. Spinal nerves emerge sequentially from the spinal cord with the spinal nerve closest to the head (C1) emerging in the space above the first cervical vertebra. The cranial nerves, however, emerge from the central nervous system above this level. Each"
"to the pharynx. In most other nematodes, these specialised cells have been replaced by an organ consisting of two parallel ducts connected by a single transverse duct. This transverse duct opens into a common canal that runs to the excretory pore. Four peripheral nerves run the length of the body on the dorsal, ventral, and lateral surfaces. Each nerve lies within a cord of connective tissue lying beneath the cuticle and between the muscle cells. The ventral nerve is the largest, and has a double structure forward of the excretory pore. The dorsal nerve is responsible for motor control, while"
"149,000 km. There is a decline in total length with age of about 10% each decade such that a man at 80 years of age has 97,200 km and a female 82,000 km. Most of this reduction is due to the loss of thinner fibers. White matter is the tissue through which messages pass between different areas of gray matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). This myelin is found in almost all long nerve fibers, and acts as an electrical insulation. This is"
"canal via an intervertebral foramen, two layers of the spinal meninges, the arachnoid and the dura invaginate the nerve to form a dural sleeve of connective tissue, which is the epineurium. The outer portion of this sleeve comprises the external epineurium which permits longitudinal nerve excursion and absorption of longitudinal stress. The layer of the epineurium that extends within the nerve to define the fascicles is termed the internal epineurium. Together, these two layers form the epineurium, which varies in thickness along the course of a nerve. The epineurium is usually most abundant around joints, as its function is to"
"Thoracodorsal nerve The thoracodorsal nerve is a nerve present in humans and other animals, also known as the middle subscapular nerve or the long subscapular nerve. It supplies the latissimus dorsi muscle. It arises from the brachial plexus. It derives its fibers from the sixth, seventh, and eighth cervical nerves. It is derived from their ventral rami, in spite of the fact that the latissimus dorsi is found in the back. The thoracodorsal nerve is a branch of the posterior cord of the brachial plexus, and is made up of fibres from the posterior divisions of all three trunks of"
"caused by damage to cranial nerve IV (trochlear nerve). Trochlear nerve The trochlear nerve, also called the fourth cranial nerve or CN IV, is a motor nerve (a somatic efferent nerve) that innervates only a single muscle: the superior oblique muscle of the eye, which operates through the pulley-like trochlea. The trochlear nerve is unique among the cranial nerves in several respects: Homologous trochlear nerves are found in all jawed vertebrates. The unique features of the trochlear nerve, including its dorsal exit from the brainstem and its contralateral innervation, are seen in the primitive brains of sharks. The human trochlear"
"study finding that mating in hamsters is reduced when the terminal nerve is severed. Terminal nerve The terminal nerve, or cranial nerve zero, was discovered by German scientist Gustav Fritsch in 1878 in the brains of sharks. It was first found in humans in 1913. A 1990 study has indicated that the terminal nerve is a common finding in the adult human brain. The nerve has been called by other names, including cranial nerve XIII, Zero Nerve, Nerve N, and NT. The terminal nerve appears just anterior of the other cranial nerves bilaterally as a microscopic plexus of unmyelinated peripheral"
"Sartorius muscle The sartorius muscle () is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment. The sartorius muscle originates from the anterior superior iliac spine and part of the notch between the anterior superior iliac spine and anterior inferior iliac spine. It runs obliquely across the upper and anterior part of the thigh in an inferomedial direction. It passes behind the medial condyle of the femur to end in a tendon. This tendon curves anteriorly to join the tendons of the gracilis"
"called nuclei. Axons within the CNS are grouped into tracts. There are 33 spinal cord nerve segments in a human spinal cord: 8 cervical segments forming 8 pairs of cervical nerves (C1 spinal nerves exit spinal column between occiput and C1 vertebra; C2 nerves exit between posterior arch of C1 vertebra and lamina of C2 vertebra; C3-C8 spinal nerves through IVF above corresponding cervica vertebra, with the exception of C8 pair which exit via IVF between C7 and T1 vertebra) 12 thoracic segments forming 12 pairs of thoracic nerves (exit spinal column through IVF below corresponding vertebra T1-T12) 5 lumbar"
"the pelvic area near the iliac spine, and supplies the skin of the anterior thigh. The obturator nerve (L2-L4) passes medially behind psoas major to exit the pelvis through the obturator canal, after which it gives off branches to obturator externus and divides into two branches passing behind and in front of adductor brevis to supply motor innervation to all the other adductor muscles. The anterior branch also supplies sensory nerves to the skin on a small area on the distal medial aspect of the thigh. The femoral nerve (L2-L4) is the largest and longest of the nerves of the"
"which contributes to the rate of lower limb amputations among this population. Overall, the poor sensation and detection may lead to changes in skin, hair, joint, and bone damage over the years for many people. Sensory nerve A sensory nerve, also called an afferent nerve, is a nerve that carries sensory information toward the central nervous system (CNS). It is a cable-like bundle of the afferent nerve fibers coming from sensory receptors in the peripheral nervous system (PNS). A motor nerve carries information from the CNS to the PNS, and both types of nerve are called peripheral nerves. Afferent nerve"
"of other neurons, muscles, or glands at their termination points. A nervous system emerges from the assemblage of neurons that are connected to each other. In vertebrates, the nervous system can be split into two parts, the central nervous system (brain and spinal cord), and the peripheral nervous system. In many species — including all vertebrates — the nervous system is the most complex organ system in the body, with most of the complexity residing in the brain. The human brain alone contains around one hundred billion neurons and one hundred trillion synapses; it consists of thousands of distinguishable substructures,"
"These include the greater occipital nerve, which provides sensation to the back of the head, the lesser occipital nerve, which provides sensation to the area behind the ears, the greater auricular nerve and the lesser auricular nerve. The phrenic nerve is a nerve essential for our survival which arises from nerve roots C3, C4 and C5. It supplies the thoracic diaphragm, enabling breathing. If the spinal cord is transected above C3, then spontaneous breathing is not possible. The last four cervical spinal nerves, C5 through C8, and the first thoracic spinal nerve, T1, combine to form the brachial plexus, or"
"Frontal nerve The frontal nerve is the largest branch of the ophthalmic nerve(V), and may be regarded, both from its size and direction, as the continuation of the nerve. It enters the orbit through the superior orbital fissure, not running within the tendinous ring, and runs forward between the levator palpebrae superioris and the periosteum. Midway between the apex and base of the orbit it divides into two branches, supratrochlear nerve and supraorbital nerve. It provides the sensory innervations for the skin of the forehead, mucosa of frontal sinus, and the skin of the upper eyelid via general somatic afferent"