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Spinal nerve

Spinal nerves are mixed nerves that originate from the spinal cord and form part of the peripheral nervous system, transmitting sensory, motor, and autonomic signals between the central nervous system and the body's periphery.^[1] There are 31 pairs of spinal nerves in total, distributed across five regions: 8 cervical (C1–C8), 12 thoracic (T1–T12), 5 lumbar (L1–L5), 5 sacral (S1–S5), and 1 coccygeal (Co1).^[1] Each spinal nerve emerges laterally from the spinal cord through the intervertebral foramina, where it is formed by the union of a dorsal root (carrying sensory afferents) and a ventral root (carrying motor efferents), which join via fila radicularia.^[1] Immediately after exiting the spinal column, each spinal nerve divides into a dorsal ramus, which innervates the posterior skin and muscles of the trunk and limbs, and a ventral ramus, which supplies the anterior and lateral regions, including the limbs.^[1] The dorsal root contains sensory fibers from the periphery, including somatic and visceral sensations organized into dermatomes, while the ventral root conveys motor fibers to skeletal muscles, forming myotomes.^[1] Additionally, spinal nerves include autonomic fibers: sympathetic preganglionic neurons originate from the thoracic and upper lumbar segments (T1–L2), whereas parasympathetic fibers arise from the sacral segments (S2–S4).^[1] These nerves are essential for integrating sensory input with motor output, enabling reflexes, voluntary movements, and regulation of involuntary functions such as heart rate and digestion.^[1] Damage to spinal nerves, often due to compression or inflammation, can lead to radiculopathy, characterized by pain, weakness, or sensory loss in specific dermatomes or myotomes, aiding in clinical diagnosis.^[1]

Structure

Roots and formation

The spinal cord gives rise to 31 pairs of spinal nerves, which emerge bilaterally from its segments through distinct root structures. Each spinal nerve originates from the convergence of a dorsal (posterior) root and a ventral (anterior) root, with the dorsal root consisting of sensory fibers and the ventral root comprising motor fibers. These roots are formed by bundles of rootlets, typically numbering around 8 per root, that attach to the spinal cord via the posterolateral and anterolateral sulci, respectively.^[2]^[3] The dorsal roots feature prominent swellings known as dorsal root ganglia, located just proximal to the union site; these ganglia contain the cell bodies of pseudounipolar sensory neurons whose peripheral processes extend to peripheral tissues and central processes enter the spinal cord. In contrast, the ventral roots lack such ganglia, as their neuron cell bodies reside within the spinal cord's ventral horn. The rootlets of the dorsal root emerge from the cord and travel to the ganglion before continuing as the root proper, while ventral rootlets directly form the root without interruption.^[4]^[3] The dorsal and ventral roots converge to form the mixed spinal nerve within the intervertebral foramen, through which the nerve exits the vertebral canal. This union occurs distal to the dorsal root ganglion and proximal to the nerve's subsequent divisions. Root lengths vary along the spinal axis: shorter in the cervical and thoracic regions, where they exit near their segmental origin, and progressively longer in the lumbar and sacral regions due to the spinal cord terminating at the L1-L2 level, resulting in an elongated bundle known as the cauda equina.^[3]^[1]^[4] Once formed, the spinal nerve briefly remains undivided before branching into dorsal and ventral rami to innervate surrounding structures.^[2]

Rami and branches

After exiting the intervertebral foramen, each spinal nerve divides into a dorsal (posterior) ramus and a ventral (anterior) ramus, both containing mixed sensory and motor fibers.^[1] The dorsal ramus is typically smaller and supplies the paraspinous muscles and overlying skin at the corresponding vertebral level.^[1] In contrast, the ventral ramus is larger and provides the primary innervation to the anterior and lateral trunk as well as the limbs.^[1] Spinal nerves also give rise to meningeal branches, including the recurrent meningeal nerve, which re-enters the vertebral canal to supply the dura mater, vertebrae, and intervertebral discs.^[5] The sinuvertebral nerve, a specific recurrent meningeal branch, originates from the ventral ramus just distal to the dorsal root ganglion and combines with a sympathetic contribution from the gray ramus communicans before re-entering the spinal canal through the intervertebral foramen.^[6] Additionally, spinal nerves connect to the sympathetic trunk via gray and white rami communicantes. The white rami communicantes, present from spinal levels T1 to L2, carry preganglionic sympathetic fibers from the spinal nerve to the paravertebral ganglia.^[1] The gray rami communicantes, found at all spinal levels, convey postganglionic sympathetic fibers from the sympathetic chain back to the spinal nerves for distribution to peripheral structures.^[1] The dorsal rami often divide into medial, lateral, and sometimes intermediate branches to reach the erector spinae muscles and associated dermatomes.^[7] Ventral rami, depending on the spinal level, either continue as intercostal nerves for the thoracic wall or interconnect to form plexuses such as the cervical, brachial, or lumbosacral plexuses for limb innervation.^[1]

Development

Embryological origins

The embryological development of spinal nerves begins during the third week of gestation with the formation of the neural plate from ectodermal cells induced by the underlying notochord. By the end of the fourth week, the neural folds elevate and fuse to form the neural tube, which closes caudally by day 28 at approximately the 25-somite stage (site corresponding to the level of future somite 31), establishing the foundational structure for the spinal cord.^[8] At this stage, neural crest cells delaminate from the dorsal neural tube and migrate ventrolaterally through the anterior half of the somites' sclerotome, aligning with the segmental metameres to ensure the future spinal nerves correspond to somite levels.^[9] Sensory components of the spinal nerves originate from neural crest cells during week 4, which migrate to form the dorsal root ganglia adjacent to the developing spinal cord. These cells differentiate into pseudounipolar sensory neurons that extend central processes into the dorsal horn of the neural tube and peripheral processes to target tissues. In contrast, motor components arise from ventral horn motor neurons within the basal plate of the neural tube, which extend axons to form the ventral roots beginning in week 4. The dorsal and ventral roots initially develop separately but converge by embryonic stage 13 (approximately week 5, with around 30 somites), uniting to create the spinal nerve proper, with segmentation ensuring one pair per metamere.^[10]^[9] By week 8, the spinal nerves have segmented into 31 pairs, corresponding to the cervical (8), thoracic (12), lumbar (5), sacral (5), and coccygeal (1) levels, as the embryonic spinal cord extends the full length of the vertebral canal and nerves exit through intervertebral foramina. This segmentation is tightly coupled with somite formation, which peaks at about 38-42 pairs but stabilizes to support the 31 spinal nerve pairs through sclerotome contributions to vertebrae. Hox genes play a critical role in this process, providing rostrocaudal patterning through their clustered, collinear expression along the neural tube and crest derivatives; for instance, 3' Hox genes (e.g., HoxA1) specify rostral identities, while 5' genes (e.g., HoxD13) define caudal ones, ensuring segment-specific nerve identities in dorsal root ganglion neurons and motor pools.^[11]^[12]

Congenital variations

Congenital variations in spinal nerves arise from disruptions during embryonic development, leading to structural anomalies that can affect nerve root formation, attachment, and function. These variations often manifest as part of broader spinal dysraphisms and may result in neurological deficits, such as sensory loss, motor weakness, or autonomic dysfunction, depending on the affected level.^[13] Spina bifida, a neural tube defect, is a prominent congenital anomaly associated with spinal nerve variations, including nerve root tethering and agenesis. In this condition, incomplete closure of the neural tube leads to exposure or malformation of the spinal cord and meninges, often causing the conus medullaris to remain low and tethered by fibrous bands or lipomatous tissue, which restricts nerve root mobility and can result in progressive stretching and ischemia of lumbosacral roots. Severe forms, such as myelomeningocele, may involve agenesis of multiple nerve roots due to direct neural tissue exposure and scarring. The incidence of spina bifida is approximately 3.5 per 10,000 live births (1 in 2,875) in the United States, as of 2024,^[14] with maternal folate deficiency as a key environmental risk factor that impairs DNA synthesis and neural tube closure; periconceptional folic acid supplementation reduces this risk by up to 70%.^[15]^[16]^[17]^[15] Caudal regression syndrome represents another critical variation impacting lumbosacral spinal nerves, characterized by partial or complete agenesis of the sacrum and lower lumbar vertebrae, which disrupts the formation and caudal migration of neural elements. This results in a truncated spinal cord (high conus) and hypoplastic or absent lumbosacral nerve roots, leading to neurogenic bladder, lower limb paresis, and sensory impairments. The syndrome is rare, with an incidence of about 1-2 per 100,000 births, and is linked to genetic factors such as maternal diabetes, alongside potential environmental influences.^[18]^[19] Anomalous nerve root formations, such as conjoined roots and duplicated ganglia, constitute subtler congenital variations that may remain asymptomatic or complicate surgical interventions. Conjoined nerve roots, the most common developmental anomaly of the cauda equina, occur when adjacent roots (typically L4-S1) share a single dural sheath, affecting 6-14% of individuals and potentially mimicking disc herniation on imaging due to altered root trajectories. Duplicated spinal ganglia, rarer and often associated with split cord malformations like diastematomyelia, involve paramedian replication of dorsal root ganglia, as observed histologically in cases of spinal cord duplication, leading to aberrant sensory innervation. These anomalies arise from incomplete separation of neural crest derivatives during weeks 4-6 of gestation.^[20]^[21] Prenatal diagnosis of these spinal nerve variations relies heavily on magnetic resonance imaging (MRI), which provides superior soft-tissue resolution compared to ultrasound for detecting tethered cords, root agenesis, or duplicated structures. Fetal MRI, typically performed after 18 weeks gestation, can identify associated anomalies like Chiari II malformation in spina bifida or sacral hypoplasia in caudal regression, enabling informed counseling and planning for postnatal interventions such as detethering surgery.^[22]^[23]

Regional characteristics

Cervical nerves

The cervical spinal nerves consist of eight pairs, designated C1 through C8, which emerge from the spinal cord in the cervical region. Unlike the other spinal nerves, the first seven cervical nerves (C1–C7) exit the vertebral column superior to their correspondingly named vertebrae, while the C8 nerve exits inferior to the C7 vertebra and superior to the T1 vertebra. This configuration arises from an embryological caudal shift of the vertebral column relative to the spinal nerves during development, resulting in eight nerves despite only seven cervical vertebrae.^[24] The C1 spinal nerve, also known as the suboccipital nerve, is unique among the cervical nerves as it often lacks a distinct dorsal root ganglion; in approximately 50% of cases, its dorsal rootlets fuse with the spinal accessory nerve (cranial nerve XI), eliminating a separate ganglion. This nerve primarily provides motor innervation to the suboccipital muscles without significant sensory components.^[25] The courses of the cervical nerves vary by level. The C1–C4 nerves have relatively short trajectories within the neck, with their ventral rami contributing to the cervical plexus and piercing the investing layer of deep cervical fascia to supply local structures. In contrast, the C5–C8 nerves have longer paths, passing between the anterior and middle scalene muscles before their ventral rami interconnect to form the brachial plexus, which extends into the upper limb.^[24]^[26] Notable contributions from these nerves include the phrenic nerve, formed by branches from the anterior rami of C3–C5, which provides essential motor and sensory innervation to the diaphragm. Additionally, the greater occipital nerve arises from the medial branch of the C2 dorsal ramus, supplying sensory innervation to the posterior scalp and occipital region.^[27]^[28] Cervical dermatomes and myotomes reflect segmental innervation patterns, with C2–C3 primarily serving the posterior head, scalp, and neck regions for both sensory and motor functions. The C5–T1 nerves, in turn, supply the dermatomes and myotomes of the upper limb, encompassing the shoulder, arm, forearm, and hand.^[29]^[24]

Thoracic nerves

The thoracic spinal nerves consist of 12 pairs, designated T1 through T12, emerging from the corresponding segments of the thoracic spinal cord. Each nerve forms by the union of dorsal and ventral roots, with the dorsal root carrying sensory fibers and the ventral root carrying motor fibers, before exiting via the intervertebral foramina. Unlike cervical nerves, which contribute significantly to limb plexuses, thoracic nerves primarily provide segmental innervation to the trunk, with no major plexuses formed from their ventral rami except for a partial contribution from T1.^[1] The ventral rami of T2 through T11 give rise to the intercostal nerves, which course anteriorly within the intercostal spaces, traveling in the costal grooves along the inferior borders of the ribs to protect the neurovascular bundle. These nerves supply the intercostal muscles and associated structures of the chest wall. The ventral ramus of T1 largely joins the brachial plexus to innervate the upper limb and pectoral region, while its smaller intercostal branch participates in chest wall innervation. The ventral ramus of T12 forms the subcostal nerve, which passes below the twelfth rib to enter the abdominal wall, avoiding the intercostal spaces. T7 through T11 are classified as thoracoabdominal nerves, extending beyond the thoracic cage to reach the abdominal wall.^[1]^[30] The dorsal rami of all thoracic nerves are smaller than the ventral rami and divide into medial and lateral branches shortly after formation, primarily innervating the paraspinal muscles such as the erector spinae and overlying skin in corresponding dermatomes. Above T6, the medial branches provide cutaneous innervation to the back, whereas below T6, the lateral branches assume this role. From the intercostal nerves, lateral cutaneous branches emerge at the midaxillary line, dividing into anterior and posterior components to supply sensory innervation to the lateral skin of the chest and abdomen. Additionally, typical intercostal nerves from T2 through T6 emit collateral branches that descend within the intercostal space to innervate the inferior portions of the intercostal muscles, parietal pleura, and periosteum of the ribs.^[1]^[30] Thoracic nerves collectively innervate the skin and muscles of the chest wall via intercostal branches, with lower thoracic nerves (T7-T12) extending to the anterior abdominal wall, supplying muscles such as the external oblique, internal oblique, transversus abdominis, and rectus abdominis, as well as the overlying skin and parietal peritoneum. This segmental arrangement supports respiratory movements through intercostal muscle contraction and provides somatic sensation to the trunk.^[30]

Lumbar nerves

The lumbar spinal nerves comprise five pairs, labeled L1 through L5, each emerging from the spinal column via the intervertebral foramina directly inferior to its corresponding vertebra. Below the level of the L1 vertebra, these nerves travel as part of the cauda equina within the lumbar cistern before exiting. This arrangement positions the L1 to L5 nerves to primarily innervate structures of the lower trunk, pelvis, and lower limbs. Upon exiting the intervertebral foramina, each lumbar spinal nerve divides into a smaller dorsal (posterior) ramus and a larger ventral (anterior) ramus. The dorsal rami course posteriorly to supply the deep muscles of the back, such as the erector spinae, and the overlying skin along the paravertebral region. In contrast, the ventral rami of L1 through L4 travel obliquely through or anterior to the psoas major muscle, where they anastomose to form the lumbar plexus, a network that extends innervation to the anterior abdominal wall, iliac region, and proximal lower limb. Several key branches arise directly from the upper lumbar nerves before plexus formation. The iliohypogastric and ilioinguinal nerves, both originating primarily from L1 (with minor contributions from T12), pierce the internal oblique and transversus abdominis muscles to innervate the lower abdominal wall and provide sensory supply to the skin over the suprapubic region, upper medial thigh, and external genitalia. The genitofemoral nerve emerges from the ventral rami of L1 and L2, bifurcating into a genital branch that innervates the cremaster muscle in males and supplies sensation to the scrotum or labia majora, and a femoral branch that provides cutaneous innervation to the upper anterior thigh. Additionally, the ventral rami of L1 through L4 contribute to the innervation of the lower abdominal wall via direct muscular branches, while L2 through L4 specifically form the femoral nerve, which supplies motor innervation to the anterior thigh muscles (e.g., quadriceps femoris for knee extension) and sensory fibers to the skin of the anterior thigh and medial leg. The sensory distribution of the lumbar nerves follows distinct dermatomal patterns on the lower body. The L1 dermatome covers the groin, upper lateral thigh, and adjacent lower abdominal skin; the L4 dermatome includes the medial knee, anterior lower leg, and medial ankle; and the L5 dermatome encompasses the lateral leg, anterolateral calf, and dorsum of the foot up to the big toe.

Sacral and coccygeal nerves

The sacral spinal nerves comprise five pairs, labeled S1 through S5, originating from the sacral segments of the spinal cord, while the coccygeal nerves consist of a single pair, designated Co1, arising from the coccygeal segment.^[1] These nerves emerge as mixed sensory and motor pathways, with S1 through S4 exiting the sacral canal via the anterior and posterior sacral foramina, and S5 along with Co1 passing through the sacral hiatus.^[31] Upon formation, each nerve divides into a dorsal ramus and a ventral ramus; the dorsal rami of the sacral nerves innervate the paraspinal muscles and overlying skin in the gluteal area, whereas the ventral rami of S1-S4 converge on the posterior pelvic wall to form the sacral plexus, anterior to the piriformis muscle.^[32] The ventral ramus of Co1, in conjunction with those of S4 and S5, contributes to the small coccygeal plexus.^[33] Key branches from the sacral nerves include contributions from S2-S4 to the pudendal nerve, which traverses the greater sciatic foramen, loops around the sacrospinous ligament, and re-enters the pelvis via the lesser sciatic foramen to supply the perineal structures.^[32] This nerve provides motor innervation to the external anal and urethral sphincters, as well as sensory fibers to the perineal skin, including the genitalia and surrounding areas.^[32] The ventral rami of S1-S3, along with L4 and L5, form the sciatic nerve, the largest branch of the sacral plexus, which exits the pelvis through the greater sciatic foramen and descends to innervate the posterior thigh muscles, such as the biceps femoris, semitendinosus, and semimembranosus.^[32] Additionally, pelvic splanchnic nerves arising from S2-S4 carry parasympathetic fibers to the bladder and rectum, regulating visceral functions like micturition and defecation.^[1] The anococcygeal nerve, derived from the coccygeal plexus involving Co1, consists of fine filaments that pierce the sacrotuberous ligament to deliver sensory innervation exclusively to the skin overlying and around the coccyx.^[34] In terms of dermatomes, S2-S4 supply sensory coverage to the perianal region, encompassing the skin of the buttocks' medial aspects, the gluteal cleft, genitals, and perineum between the anus and genitalia, while the Co1 dermatome is limited to the thin skin adjacent to the coccyx.^[35] These distributions ensure comprehensive sensory mapping of the pelvic and lower posterior body regions.^[35]

Functions

Sensory roles

Spinal nerves convey sensory information from the periphery to the central nervous system primarily through afferent fibers originating in the dorsal roots. These fibers transmit somatosensory signals, including touch, pain, and temperature, as well as proprioceptive information about body position and movement. The cell bodies of these sensory neurons are located in the dorsal root ganglia, where they form pseudounipolar structures with a single axon that bifurcates into peripheral and central processes.^[36]^[2]^[1] The skin and underlying tissues are organized into dermatomes, which are segmental areas innervated by specific spinal nerves, allowing for precise localization of sensory input. For instance, the C6 dermatome covers the thumb and radial forearm, while the L5 dermatome includes the big toe and dorsum of the foot. These mappings reflect the embryonic segmentation of the body and provide a clinical framework for assessing sensory integrity, though individual variations exist.^[37]^[38] Upon entering the spinal cord via the dorsal roots, the central processes of these pseudounipolar neurons synapse in the dorsal horn. Fine touch and proprioception ascend ipsilaterally through the dorsal column-medial lemniscus pathway, while pain and temperature signals cross to the contralateral anterolateral system via the spinothalamic tract. This organization enables discriminatory and affective processing of sensory modalities in higher brain centers.^[39]^[40]^[41] Visceral afferents, conveying sensations from internal organs such as distension or chemical irritation, also travel through the dorsal roots but often join spinal nerves via the white rami communicantes in the thoracolumbar region. These unmyelinated fibers originate from pseudounipolar neurons in the dorsal root ganglia and project to the dorsal horn, integrating with somatic pathways for autonomic sensory processing. Visceral afferents from pelvic organs (e.g., bladder, rectum, genitals) similarly enter via the dorsal roots of sacral spinal nerves (S2–S4), without involvement of rami communicantes.^[42]^[2]^[43] At the spinal level, pain transmission is modulated by the gate control theory, which posits a gating mechanism in the dorsal horn where non-noxious inputs from large-diameter afferents can inhibit nociceptive signals from small-diameter fibers. This substantia gelatinosa-mediated process, influenced by descending pathways, explains phenomena like pain relief from rubbing an injured area. The theory, proposed by Melzack and Wall, revolutionized understanding of pain modulation by emphasizing central integration over peripheral specificity.^[44]^[45]

Motor roles

Spinal nerves carry efferent motor fibers originating from the ventral roots of the spinal cord, which emerge from the anterior horn and convey signals to skeletal muscles for voluntary and reflexive movements.^[1] These fibers primarily consist of lower motor neurons, whose cell bodies reside in the ventral horn, enabling direct control over muscle contraction and posture.^[1] The efferent fibers include two main types of motor neurons: alpha motor neurons, which innervate extrafusal muscle fibers to produce force and movement, and gamma motor neurons, which regulate the sensitivity of muscle spindles by innervating intrafusal fibers.^[46] Alpha motor neurons form large axons that exit via the ventral roots and travel through spinal nerves to reach skeletal muscles, while gamma motor neurons maintain muscle spindle tone during contraction.^[3] Myotomes represent the segmental organization of motor innervation, where each spinal nerve level supplies a specific group of muscles derived from the same embryological somite.^[47] For instance, the C5 spinal nerve primarily innervates the deltoid muscle for shoulder abduction, while the S1 nerve supplies the gastrocnemius for plantar flexion of the foot.^[48] This mapping allows for precise assessment of spinal nerve integrity through targeted muscle testing.^[1] Lower motor neurons exit the spinal cord through the ventral roots, which unite with dorsal roots to form spinal nerves; the motor fibers then predominantly course through the ventral rami to peripheral nerves, ultimately synapsing at neuromuscular junctions on skeletal muscle fibers.^[4] At these junctions, acetylcholine release triggers muscle contraction, ensuring efficient transmission of motor commands.^[49] Spinal nerves facilitate reflex arcs, such as the monosynaptic stretch reflex, where sensory input from muscle spindles via dorsal roots directly excites alpha motor neurons in the ventral horn, leading to rapid muscle contraction without higher brain involvement.^[50] This arc exemplifies the spinal cord's role in automatic motor responses to maintain posture and limb position.^[51] Upper motor neurons from the corticospinal tract descend through the spinal cord to synapse on lower motor neurons in the ventral horn, modulating voluntary motor output and fine-tuning spinal reflexes via excitatory and inhibitory influences.^[52] Motor signals from spinal nerves are often distributed through plexuses, such as the brachial plexus for upper limb innervation.^[1]

Autonomic contributions

Spinal nerves carry autonomic fibers that contribute to the involuntary regulation of visceral functions, integrating with the sympathetic and parasympathetic divisions of the autonomic nervous system. The sympathetic component originates from preganglionic neurons in the intermediolateral cell column of the spinal cord from levels T1 to L2, forming the thoracolumbar outflow.^[53] These preganglionic fibers exit the spinal cord via the anterior roots of the corresponding spinal nerves and connect to the sympathetic chain ganglia through white rami communicantes, which are myelinated and carry efferent signals to paravertebral or prevertebral ganglia.^[54] Postganglionic fibers, which are unmyelinated and release norepinephrine, then rejoin all spinal nerves via gray rami communicantes, distributing to targets such as blood vessels, sweat glands, and arrector pili muscles throughout the body.^[55] This sympathetic pathway supports the "fight-or-flight" response, promoting physiological changes like vasodilation in skeletal muscles, increased heart rate, and sweating to enhance survival during stress.^[53] For instance, sympathetic activation via spinal nerves triggers piloerection by stimulating arrector pili muscles, a reflex that raises body hair to trap air for insulation.^[54] Although autonomic fibers travel alongside somatic fibers in mixed spinal nerves, they diverge at the rami communicantes to innervate visceral and glandular targets independently of voluntary control.^[55] The parasympathetic contribution arises primarily from spinal nerves S2 to S4, constituting the sacral portion of the craniosacral outflow—though this classification has been debated since 2016, with some studies proposing it is sympathetic based on genetic and developmental evidence, a view not yet widely accepted in standard anatomy as of 2025.^[56]^[57] Preganglionic parasympathetic fibers exit these sacral spinal nerves through their anterior roots and form the pelvic splanchnic nerves (nervi erigentes), which bypass nearby ganglia and synapse in intramural ganglia near target organs in the pelvis.^[53] These long preganglionic fibers, which release acetylcholine, innervate structures such as the descending and sigmoid colon, rectum, bladder, and reproductive organs, with short postganglionic fibers also cholinergic.^[54] Parasympathetic activity facilitates the "rest-and-digest" functions, such as promoting gastrointestinal motility and bladder contraction for micturition.^[55] A key reflex example is the parasympathetic-mediated detrusor muscle contraction in the bladder, coordinated via S2-S4 spinal nerves to enable urination during relaxation.^[53] This sacral outflow complements cranial parasympathetic inputs but remains distinct in its reliance on spinal nerves for pelvic visceral control.^[54]

Spinal plexuses

Cervical and brachial plexuses

The cervical plexus is formed by the ventral rami of the first four cervical spinal nerves (C1–C4), which intermix in the neck to produce a network of sensory and motor branches primarily innervating the skin and muscles of the neck, as well as contributing to diaphragmatic function.^[24] These rami emerge from the intervertebral foramina and converge posterior to the sternocleidomastoid muscle, forming loops that give rise to superficial sensory nerves such as the lesser occipital (innervating the scalp behind the ear), great auricular (sensory to the skin over the parotid gland and angle of the mandible), transverse cervical (sensory to the anterior and lateral neck), and supraclavicular nerves (sensory to the skin of the shoulder and upper chest).^[24] Motor branches include the ansa cervicalis, a loop (C1–C3) that supplies infrahyoid muscles like the omohyoid, sternohyoid, and sternothyroid for neck flexion and head stabilization, while the phrenic nerve (primarily C4 with contributions from C3–C5) provides essential motor innervation to the diaphragm, enabling respiration.^[24]^[58] The brachial plexus arises from the ventral rami of spinal nerves C5 through T1, which intermingle in the neck and axilla to form a complex structure supplying motor and sensory innervation to the upper limb, including the shoulder, arm, forearm, and hand.^[59] These roots exit the spinal column and unite into three trunks—superior (C5–C6), middle (C7), and inferior (C8–T1)—within the interscalene (scalene) triangle, a space bounded by the anterior scalene muscle anteriorly, middle scalene posteriorly, and the first rib inferiorly, where the plexus accompanies the subclavian artery.^[59]^[60] Each trunk then divides into anterior and posterior divisions behind the clavicle, which recombine into three cords in the axilla: lateral (anterior divisions of superior and middle trunks), posterior (posterior divisions of all trunks), and medial (anterior division of inferior trunk).^[59] The cords give rise to terminal branches, including the musculocutaneous nerve (from lateral cord, innervating anterior arm muscles like the biceps brachii for elbow flexion), median nerve (from lateral and medial cords, supplying forearm flexors and thenar hand muscles for wrist and finger flexion), ulnar nerve (from medial cord, innervating forearm flexors and hand intrinsics for finger adduction and abduction), axillary nerve (from posterior cord, motor to deltoid for shoulder abduction), and radial nerve (from posterior cord, innervating posterior arm and forearm extensors for elbow, wrist, and finger extension).^[59] As the plexus passes through the costoclavicular space—between the clavicle superiorly and first rib inferiorly—the cords and subclavian vessels are vulnerable to compression.^[60] The brachial plexus provides myotomal motor innervation to upper limb muscles (e.g., C5–C6 for shoulder abduction and elbow flexion, C7 for elbow extension and wrist flexion, C8–T1 for finger flexion and intrinsics) and dermatomal sensory coverage (e.g., C5 over the lateral shoulder, C6–C7 along the arm and forearm, C8–T1 to the medial hand and fingers).^[59] Formation involves extensive rami intermixing, allowing functional reorganization, but this complexity predisposes to injuries like Erb's palsy (upper plexus traction at C5–C6, causing "waiter's tip" posture with shoulder adduction and internal rotation) and Klumpke's paralysis (lower plexus at C8–T1, leading to claw hand deformity with intrinsic muscle weakness).^[61]

Lumbosacral plexuses

The lumbosacral plexuses are complex networks of nerves formed by the anterior (ventral) rami of the spinal nerves from the lumbar and sacral regions, collectively innervating the lower abdomen, pelvis, perineum, buttocks, thighs, legs, and feet.^[62] These plexuses arise from the ventral rami converging anterior to the sacrum and within the psoas major muscle, enabling coordinated sensory and motor functions for lower body mobility and pelvic organ support.^[63] The lumbosacral trunk, a continuation of the L4 ventral ramus joined by L5, serves as a critical link between the lumbar and sacral plexuses, facilitating integrated innervation across the lower trunk.^[64] The lumbar plexus specifically originates from the ventral rami of spinal nerves L1 through L4, forming within the substance of the psoas major muscle and projecting laterally and caudally from the intervertebral foramina.^[63] Its branches include the iliohypogastric and ilioinguinal nerves (primarily from L1), which provide sensory innervation to the skin of the groin and upper medial thigh; the genitofemoral nerve (L1-L2), supplying the skin of the scrotum or labia majora and cremaster muscle; the lateral femoral cutaneous nerve (L2-L3), innervating the skin of the lateral thigh; the femoral nerve (L2-L4), the largest branch, which motor innervates the quadriceps femoris, iliacus, pectineus, and sartorius muscles while providing sensory input from the anterior thigh and medial leg via the saphenous nerve; and the obturator nerve (L2-L4), innervating the adductor muscles of the thigh and providing sensory branches to the medial thigh skin.^[65] Muscular branches also supply the psoas major, quadratus lumborum, and lumbar intertransversarii.^[63] The sacral plexus forms from the ventral rami of L4 through S4, located in the pelvis anterior to the piriformis muscle and lateral to the sacrum, with contributions from the lumbosacral trunk augmenting its upper portion.^[62] Key branches include the superior and inferior gluteal nerves (L4-S1 and L5-S2, respectively), which motor innervate the gluteus maximus, medius, and minimus for hip extension and abduction; the nerve to quadratus femoris (L4–S1), supplying the quadratus femoris and inferior gemellus; and the nerve to obturator internus (L5–S2), supplying the obturator internus and superior gemellus, for hip rotation; the posterior femoral cutaneous nerve (S1-S3), providing sensory innervation to the posterior thigh and perineum; the pudendal nerve (S2-S4), innervating the perineum, external genitalia, and pelvic floor muscles for sensory and motor functions in micturition and defecation; and the sciatic nerve (L4-S3), the largest branch, which exits the pelvis through the greater sciatic foramen inferior to the piriformis muscle and divides into the tibial nerve (L4-S3, innervating posterior thigh muscles like hamstrings, and posterior leg/sole of foot muscles and skin) and common peroneal (fibular) nerve (L4-S2, supplying anterior and lateral leg muscles for dorsiflexion and eversion, plus foot skin).^[66]^[65] Overall, these plexuses cover dermatomes from L1 (inguinal region) to S3 (perineum), with examples including L4 for the medial leg and S1 for the lateral foot and sole.^[1]

Clinical significance

Injuries and trauma

Traumatic injuries to spinal nerves can occur through several mechanisms, including avulsion, where the nerve root is torn from the spinal cord, often during high-force events such as brachial plexus injuries in childbirth. Compression injuries typically arise from external pressure, such as a herniated intervertebral disc that impinges on the nerve root, leading to radiculopathy. Lacerations result from sharp penetrating trauma, like stab wounds, which sever the nerve fibers directly.^[67]^[68]^[69] Specific examples illustrate the clinical impact of these injuries. Erb-Duchenne palsy, affecting the C5-C6 nerve roots in the upper brachial plexus, produces a characteristic "waiter's tip" posture due to paralysis of shoulder abductors, external rotators, and elbow flexors, with the arm adducted, internally rotated, and pronated. In the lower body, L5 spinal nerve root injury, such as from disc herniation, can cause foot drop, weakness in ankle dorsiflexion, and sensory deficits along the lateral leg and dorsum of the foot.^[67]^[70] Pathophysiologically, injury triggers Wallerian degeneration in the distal nerve segment, involving axonal fragmentation and myelin sheath breakdown over days to weeks, which clears debris to potentially allow regeneration. Disorganized axonal sprouting may lead to neuroma formation, a tangled mass of nerve tissue that can cause chronic pain or hypersensitivity at the injury site.^[71]^[72] Diagnosis relies on clinical symptoms such as flaccid paralysis in affected myotomes and sensory loss confined to specific dermatomes, alongside electrodiagnostic tests like electromyography (EMG) to detect denervation and nerve conduction studies to measure slowed or absent impulses.^[73]^[74] Treatment often involves surgical intervention, such as nerve grafting to bridge gaps in lacerated or avulsed nerves using autologous donor tissue, combined with physical therapy to preserve joint mobility, strengthen unaffected muscles, and facilitate reinnervation. Prognosis depends on injury severity and location as well as treatment timing; cervical injuries may benefit from shorter regeneration distances to upper limb targets compared to lumbar injuries to the lower limbs, though plexus complexity can influence outcomes. Partial functional restoration is possible with early intervention.^[75]

Disorders and pathologies

Radiculopathy refers to the compression or irritation of spinal nerve roots, often due to degenerative changes such as herniated intervertebral discs or spinal stenosis, leading to radiating pain along the affected nerve's distribution. In the lumbar region, particularly involving the L4-S1 nerve roots, this commonly manifests as sciatica, characterized by sharp, shooting pain extending from the lower back through the buttock and down the leg, accompanied by potential numbness or weakness in the foot.^[76] Cervical radiculopathy, frequently affecting the C6-C7 roots, produces similar symptoms in the upper limbs, including pain radiating to the shoulder, arm, and hand, along with sensory deficits or motor impairment in the biceps or triceps.^[77] Cauda equina syndrome results from compression of the lumbosacral spinal nerve roots below the conus medullaris, often due to massive disc herniation or tumor. Symptoms include severe low back pain, bilateral sciatica, saddle anesthesia, leg weakness, and bowel/bladder dysfunction. It requires urgent surgical decompression to prevent irreversible neurological deficits.^[78] Herpes zoster, commonly known as shingles, results from the reactivation of the varicella-zoster virus (VZV) latent in the dorsal root ganglia of spinal nerves following an initial chickenpox infection. This reactivation causes inflammation and neuronal damage, leading to a unilateral vesicular rash confined to one or two adjacent dermatomes, most often thoracic but potentially involving cervical or lumbar spinal nerves.^[79] The rash is typically preceded by prodromal pain or paresthesia in the affected dermatome, and postherpetic neuralgia can persist as chronic neuropathic pain beyond rash resolution.^[80] Diabetic neuropathy encompasses a range of nerve disorders in individuals with diabetes mellitus, with distal symmetric polyneuropathy (DSPN) being the predominant form affecting spinal nerves. DSPN primarily impacts the longer axons of lumbosacral nerves due to its length-dependent nature, resulting in symmetric sensory loss, tingling, and burning pain starting in the distal lower extremities and progressing proximally.^[81] The lifetime prevalence of DSPN exceeds 50% in people with diabetes, driven by hyperglycemia-induced microvascular damage and oxidative stress, while severe cases leading to ulceration or amputation occur in approximately 15-20% of affected patients.^[82]^[83] Guillain-Barré syndrome (GBS) is an acute immune-mediated polyradiculoneuropathy that involves inflammatory demyelination of peripheral nerves, including spinal nerve roots, often triggered by preceding infections. The most common subtype, acute inflammatory demyelinating polyradiculoneuropathy (AIDP), leads to ascending symmetric paralysis beginning in the lower limbs and progressing upward, with weakness, areflexia, and potential respiratory involvement due to impaired nerve conduction.^[84] Diagnosis relies on clinical features supported by cerebrospinal fluid analysis showing elevated protein and nerve conduction studies revealing demyelination, with recovery varying based on early intervention.^[85] Tumor compression of spinal nerves arises from neoplasms such as schwannomas, which are benign nerve sheath tumors originating from Schwann cells along spinal nerve roots. These tumors, accounting for about 25% of primary intradural spinal cord tumors in adults, typically present with progressive radicular pain, sensory changes, or motor deficits due to direct compression of the affected root, most commonly in the lumbar or thoracic regions.^[86] Schwannomas are often solitary and slow-growing, with an equal male-female incidence and peak occurrence in the fourth to sixth decades, though malignant transformation is rare.^[87]

References

[1]
Neuroanatomy, Spinal Nerves - StatPearls - NCBI Bookshelf
Aug 14, 2023 · Spinal nerves are mixed nerves that interact directly with the spinal cord to modulate motor and sensory information from the body's periphery.
[2]
Spinal nerves: Anatomy, roots and function | Kenhub
Each spinal nerve contains a mixture of motor and sensory fibres. They begin as nerve roots that emerge from a segment of the spinal cord at a specific level.
[3]
Anatomy of the Spinal Cord (Section 2, Chapter 3) Neuroscience ...
The spinal cord is a cylindrical structure of nervous tissue composed of white and gray matter, is uniformly organized and is divided into four regions.
[4]
Spinal Nerves - Physiopedia
Each spinal nerve is formed by the combination of nerve fibers from the dorsal and ventral roots of the spinal cord. The dorsal roots carry afferent sensory ...Introduction · Anatomy · Rami · Plexi
[5]
Chapter 20: The thoracic wall and mediastinum
Thoracic nerves. Each of the 12 thoracic (spinal) nerves gives off a recurrent meningeal branch, emerges from an intervertebral foramen, and divides into a ...
[6]
A comprehensive review of the sinuvertebral nerve with clinical ...
The sinuvertebral nerve is a recurrent nerve that originates from the ventral ramus, re-entering the spinal canal via the intervertebral foramina.
[7]
The human lumbar dorsal rami - PMC - NIH
The L 1-4 dorsal rami tend to form three branches, medial, lateral, and intermediate, which are distributed, respectively, to multifidus, iliocostalis, ...
[8]
Neuroanatomy, Neural Tube Development and Stages - NCBI - NIH
Anterior neuropore closes on day 25, which is the 18 to 20 somite stage. Posterior neuropore closes on day 28, which is the 25 somite stage. Secondary ...
[9]
The Neural Crest - Developmental Biology - NCBI Bookshelf
It appears that the combinations of Hox genes expressed in the various regions of neural crest cells specify their fates.
[10]
Week 4 - UNSW Embryology
Aug 17, 2020 · Neural crest at spinal level is segregating, and spinal ganglia are in series with the somites. Spinal cord ventral roots beginning to develop.Missing: formation | Show results with:formation
[11]
Development of the central nervous system - Kenhub
The rostral neuropore closes around day 25, and the caudal neuropore closes approximately two days after. The neural tube becomes vascularized around the time ...Spinal Cord Development · Development Of The Brain · Clinical Notes<|control11|><|separator|>
[12]
HOX gene expression in the developing human spine - Nature
Nov 20, 2024 · Our findings shed new light on HOX gene expression in the developing spine, highlighting a HOX gene 'source code' in neural-crest cell derivatives.
[13]
Congenital Brain and Spine Malformations | Johns Hopkins Medicine
There are numerous variations of congenital malformations of the bone and soft tissue of the head and spine, including neural tube defects, such as spina bifida ...Types Of Congenital Brain... · Chiari Malformations · Encephaloceles
[14]
Spina bifida - Symptoms and causes - Mayo Clinic
Dec 19, 2023 · Spina bifida is a condition that occurs when the spine and spinal cord don't form properly. It's a type of neural tube defect.Overview · Risk Factors · Complications
[15]
Tethered Spinal Cord Syndrome
Jul 19, 2024 · Tethered spinal cord syndrome (TSCS) is a disorder of the nervous system caused by tissue that attaches itself to the spinal cord and limits the movement of ...Missing: agenesis | Show results with:agenesis
[16]
Folic Acid Supplementation to Prevent Neural Tube Defects: US ...
Aug 1, 2023 · The Centers for Disease Control and Prevention estimated that spina bifida occurs in 3.9 of 10 000 live births in the US, anencephaly in 2.5 of ...
[17]
Caudal regression syndrome - Genetics - MedlinePlus
Sep 12, 2023 · Caudal regression syndrome is a disorder that impacts the development of the lower (caudal) part of the spine.Missing: lumbosacral | Show results with:lumbosacral
[18]
Caudal Regression Syndrome - Symptoms, Causes, Treatment
Caudal regression syndrome is a broad term for a rare complex disorder characterized by abnormal development of the lower (caudal) end of the spine.Missing: lumbosacral | Show results with:lumbosacral
[19]
Conjoined nerve root | Radiology Reference Article | Radiopaedia.org
Sep 10, 2024 · Conjoined nerve roots are the most common nerve root developmental anomaly of the cauda equina, being twice as common as two roots in the same foramen.
[20]
Histological study of paramedian dorsal root ganglia in an infant with ...
Magnetic resonance imaging revealed duplication of the spinal cord below the level of L-1. On laminectomy it was discovered that the cord was tethered in the ...
[21]
Multimodality Imaging Evaluation of Fetal Spine Anomalies with ...
Nov 1, 2021 · Prenatal US and MRI can depict features of fetal spinal congenital anomalies, aid in accurate early diagnosis, and provide guidance in treatment.
[22]
Fetal magnetic resonance imaging in the diagnosis of spinal cord ...
Aug 7, 2022 · This study aimed to evaluate the value of fetal magnetic resonance imaging (MRI) in the prenatal diagnosis of spinal neural tube defects.
[23]
Anatomy, Head and Neck: Cervical Nerves - StatPearls - NCBI - NIH
Apr 6, 2025 · Cervical nerves are spinal nerves that originate from the cervical region of the spinal cord. These nerves transmit motor and sensory information.
[24]
Clinical anatomy of the C1 dorsal root, ganglion, and ramus - PubMed
In 50% of specimens, the spinal accessory nerve joined with dorsal rootlets of C1. C1 in these cases did not possess a dorsal root ganglion. There were no ...Missing: lacks | Show results with:lacks
[25]
High-resolution Imaging of Neural Anatomy and Pathology of the Neck
Jan 5, 2017 · The ventral rami of the first four cervical spinal nerves constitute the cervical plexus. They are located in front of the C1 to C4 vertebra, ...
[26]
Anatomy, Thorax, Phrenic Nerves - StatPearls - NCBI Bookshelf
Jul 24, 2023 · The phrenic nerve originates from the anterior rami of C3 through C5 and traverses the neck, heart, and lungs to reach the diaphragm.
[27]
Anatomy, Head and Neck, Occipital Nerves - StatPearls - NCBI
Greater Occipital Nerve. The GON is the biggest purely afferent nerve that arises from the medial division of the dorsal ramus of the C2 spinal nerve. · Lesser ...Structure and Function · Nerves · Physiologic Variants · Surgical Considerations
[28]
Physiology, Spinal Cord - StatPearls - NCBI Bookshelf
Mar 17, 2023 · Spinal nerves emerge from the spinal cord as rootlets, which join to form two nerve roots. The anterior nerve roots contain motor fibers ...
[29]
Anatomy, Thorax, Intercostal Nerves - StatPearls - NCBI Bookshelf
May 22, 2023 · The intercostal nerves arise from the anterior rami of the thoracic spinal nerves from T1 to T11 and are situated between adjacent ribs.
[30]
Anatomy of the Spine and Peripheral Nervous System - AANS
Nerve root – The initial portion of a spinal nerve as it originates from the spinal cord. Neural arch – The bony arch of the back part of a vertebra that ...
[31]
The Sacral Plexus - Spinal Nerves - Branches - TeachMeAnatomy
The sacral plexus is a network of nerve fibres that supplies the skin and muscles of the pelvis and lower limb.
[32]
Anatomy, Back, Coccygeal Vertebrae - StatPearls - NCBI Bookshelf
Jun 5, 2023 · The coccygeal plexus primarily innervate the coccygeal vertebrae, a network of nerves originating from the ventral rami of S4, S5, and Co1 ...
[33]
Coccygeal nerve - e-Anatomy - IMAIOS
Nervus coccygeus From this plexus the anococcygeal nerves take origin; they consist of a few fine filaments which pierce the sacrotuberous ligament to supply ...
[34]
Dermatomes: What They Are & Locations - Cleveland Clinic
Oct 27, 2022 · Dermatomes are areas of skin on your body that rely on specific nerve connections on your spine. In this way, dermatomes are much like a map.
[35]
Neuroanatomy, Dorsal Root Ganglion - StatPearls - NCBI Bookshelf
Sep 21, 2022 · Dorsal nerve roots carry sensory neural signals to the central nervous system (CNS) from the peripheral nervous system (PNS).Introduction · Structure and Function · Embryology · Surgical Considerations
[36]
Anatomy, Skin, Dermatomes - StatPearls - NCBI Bookshelf - NIH
Oct 24, 2023 · Several anatomic landmarks help easily identify or estimate different dermatomal levels. C6: Thumb. C7: Middle finger. C8: Little finger. T1: ...Missing: big | Show results with:big
[37]
Dermatomes and Myotomes | Sensation | Anatomy Geeky Medics
May 14, 2018 · A dermatome is an area of skin supplied by a single spinal nerve. If you imagine the human body as a map, each dermatome represents the area of ...
[38]
The Ascending Tracts - DCML - Anterolateral - TeachMeAnatomy
The dorsal column-medial lemniscal pathway (DCML) carries the sensory modalities of fine touch (tactile sensation), vibration and proprioception. Its name ...
[39]
14.5 Sensory and Motor Pathways – Anatomy & Physiology 2e
Spinal Nerves. Generally, spinal nerves contain afferent axons from sensory receptors in the periphery, such as from the skin, mixed with efferent axons ...
[40]
Central Pain Pathways: The Spinothalamic Tract - NCBI - NIH
When these centrally projecting axons reach the dorsal horn, they branch into ascending and descending collaterals, forming the dorsolateral tract of Lissauer ( ...
[41]
Neuroanatomy, White Rami Communicans - StatPearls - NCBI - NIH
Jul 24, 2023 · The white ramus communicans is a structure that anteriorly connects the spinal nerve to the sympathetic trunk.
[42]
Pain Mechanisms: A New Theory - Science
A gate control system modulates sensory input from the skin before it evokes pain perception and response.
[43]
Gate Control Theory of Pain - Physiopedia
The Gate Control Theory of Pain is a mechanism, in the spinal cord, in which pain signals can be sent up to the brain to be processed to accentuate the ...Introduction · Physiology · At the Spinal Cord · Useful Applications
[44]
Spinal cord tracts and reflexes - Knowledge @ AMBOSS
Apr 9, 2025 · Dorsal roots carry sensor (afferent) fibers that transmit somatosensory information. ... Sensory nerve fibers have a pseudounipolar cell ...
[45]
Myotomes: Definition and testing | Kenhub
A myotome is a group of muscles which are innervated by a single spinal nerve which has derived from the same embryological segment.
[46]
Myotomes - Physiopedia
For example, the C5 nerve root contributes to both the axillary nerve (deltoid) and musculocutaneous nerve (biceps), explaining why both shoulder abduction and ...
[47]
Lower Motor Neuron - an overview | ScienceDirect Topics
Overview The lower motor neurons of the spinal cord anterior horn form neuromuscular junctions (synapses) with skeletal muscles and are topographically ...Anatomy and Physiology of... · Neural Circuits and... · Clinical Significance and...
[48]
Monosynaptic Reflex - StatPearls - NCBI Bookshelf - NIH
Sep 12, 2022 · The monosynaptic stretch reflex, sometimes called the muscle stretch reflex or deep tendon reflex, is a reflex arc that facilitates direct communication ...
[49]
Spinal Reflex: Anatomy and Examples - Kenhub
This article describes the anatomy of spinal reflex (monosynaptic and polysynaptic), as well as some examples. Click now to learn more at Kenhub!
[50]
Corticospinal Tract - Physiopedia
The neurons that travel in the corticospinal tract are referred to as upper motor neurons; they synapse on neurons in the spinal cord called lower motor neurons ...Description · Course · Function · Clinical relevance
[51]
Anatomy, Autonomic Nervous System - StatPearls - NCBI Bookshelf
Truncal neural crest cells contribute to the dorsal root of the spinal cord and the sympathetic ganglia. The parasympathetic innervation of the heart forms from ...
[52]
Peripheral nervous system: Anatomy, divisions, functions | Kenhub
The preganglionic fibers of the sympathetic nerves leave the spinal cord through the T1 to L2 anterior roots, entering the corresponding spinal nerve. The ...Dermatomes · Myotomes · Dorsal root ganglion
[53]
Peripheral Nervous System Anatomy - Medscape Reference
Feb 10, 2025 · Nerve fibers outside the spinal cord join to form anterior (ventral) motor roots and posterior (dorsal) sensory nerve roots. The anterior and ...
[54]
The cervical plexus - PMC - PubMed Central - NIH
The cervical plexus provides sensory innervation to the whole neck and upper anterior torso and motor innervation to most muscles in the neck.
[55]
Anatomy, Head and Neck: Brachial Plexus - StatPearls - NCBI - NIH
The brachial plexus is divided, proximally to distally, into rami/roots, trunks, divisions, cords, and terminal branches. The trunks can be found within the ...Introduction · Structure and Function · Nerves · Physiologic Variants
[56]
Anatomy, Head and Neck: Inter-scalene Triangle - StatPearls - NCBI
Nov 9, 2022 · The base of the triangle is the location of the brachial plexus.[3] The plexus is involved with the motor and sensory function of the shoulder ...Introduction · Structure and Function · Nerves · Physiologic Variants
[57]
Obstetric Brachial Plexopathy (Erb's, Klumpke's Palsy) - Pediatrics
Jul 29, 2025 · Obstetric Brachial Plexopathy is injury to the brachial plexus that occurs during birth usually as a result of a stretching injury from a ...
[58]
Lumbosacral Plexopathy - StatPearls - NCBI Bookshelf
Jul 6, 2025 · The lumbosacral plexus is a network of nerves formed by the anterior rami of the lumbar and sacral spinal cord, involving the L1 to S4 nerve ...<|control11|><|separator|>
[59]
Anatomy, Back, Lumbar Plexus - StatPearls - NCBI Bookshelf
The lumbar plexus provides innervation to several important muscles. Notable muscles include the psoas muscle, quadratus lumborum, lumbar transverse muscles, ...
[60]
Anatomy, Back, Lumbosacral Trunk - StatPearls - NCBI Bookshelf
Oct 12, 2023 · The lumbosacral plexus arises as a cordlike structure from the ventral rami of the fourth and fifth lumbar nerve roots.
[61]
Nerves of the Lower Limb | UAMS Department of Neuroscience
Nerves of the Lower Limb ; cluneal, middle, lateral cutaneous branches of the dorsal primary rami of spinal nerves S1-3, no named branches, none ; cluneal, ...
[62]
Anatomy, Sciatic Nerve - StatPearls - NCBI Bookshelf
The sciatic nerve provides motor innervation to the posterior compartment of the thigh. This includes the biceps femoris, semimembranosus, semitendinosus, and ...
[63]
Erb Palsy - StatPearls - NCBI Bookshelf
Apr 8, 2023 · Erb palsy, or Erb-Duchenne paralysis, is a paralysis of the arm caused by the injury to the upper group of the main nerves supplying it.Continuing Education Activity · Introduction · Etiology · History and Physical
[64]
Herniated disk - Symptoms and causes - Mayo Clinic
Jul 18, 2025 · A herniated disk refers to a problem with one of the rubbery cushions, called disks, that sit between the bones that stack to make the spine.
[65]
Acute Nerve Injury - StatPearls - NCBI Bookshelf - NIH
Stretch-related injuries, the most common type, happen when the stretching forces overcome the nerve's elasticity. · Laceration injuries caused by sharp objects ...
[66]
Hip and pelvic fractures and sciatic nerve injury - PubMed
Hip and pelvic fractures can result in sciatic nerve injury, especially common peroneal nerve injury and prognosis is poor. Open reduction and internal ...
[67]
Wallerian degeneration | Radiology Reference Article
Mar 10, 2025 · Wallerian degeneration is the process of antegrade degeneration of the axons and their accompanying myelin sheaths due to a proximal axonal or neuronal cell ...
[68]
Traumatic neuromas of peripheral nerves: Diagnosis, management ...
A traumatic neuroma is not a true malignancy, rather, it is a hyperplastic, reparative nerve reaction after injury and typically manifests as a nodular mass.
[69]
Spinal Cord Injuries - StatPearls - NCBI Bookshelf - NIH
Jun 2, 2025 · Spinal cord injury (SCI) is a neurologic condition resulting from trauma or nontraumatic etiologies that disrupt motor, sensory, and autonomic pathways.Missing: avulsion | Show results with:avulsion
[70]
Electromyography (EMG) and Nerve Conduction Studies
Apr 10, 2024 · An EMG test helps find out if muscles are responding the right way to nerve signals. Nerve conduction studies help to check for nerve damage or ...
[71]
Nerve Graft (Nerve Transplant Surgery) - Johns Hopkins Medicine
A nerve graft, sometimes called a nerve transplant, is a piece of nerve tissue that serves as a bridge to fill a gap between the ends of a damaged nerve.
[72]
Physiotherapy Management of Individuals with Spinal Cord Injury
Gait training, strengthening, and balance exercises were the most common physiotherapy activities in individuals with an AIS D spinal cord injury. Overall ...Introduction · Physiotherapy Management · Sub-acute (Rehabilitation...
[73]
Cervical Injury - StatPearls - NCBI Bookshelf - NIH
Jun 2, 2025 · Dermatomes for the cervical spine include: C2: Posterior head and upper neck (occipital region). C3: Lateral neck, lower jaw area, and posterior ...
[74]
Radiculopathies -
Posterior sciatica * pain which radiates along the posterior thigh and the posterolateral aspect of the leg is due to an S1 or L5 radiculopathy (nerve roots).Missing: radiculitis | Show results with:radiculitis
[75]
Lumbar and Cervical Spondylosis: Symptoms & Treatments - HSS
Aug 13, 2025 · This type of nerve pain, which results from compression or inflammation of the nerve in the cervical spine, is known as cervical radiculopathy.Missing: radiculitis C6-
[76]
Herpes Zoster - StatPearls - NCBI Bookshelf
Herpes simplex, CMV, EBV, and human herpesviruses have all been found in patients with shingles. Go to: History and Physical. Zoster characteristically presents ...Introduction · Pathophysiology · History and Physical · Evaluation
[77]
Clinical Overview of Shingles (Herpes Zoster) - CDC
Jun 27, 2024 · People with herpes zoster have a rash in one or two adjacent dermatomes. The rash most commonly appears on the trunk along a thoracic dermatome ...
[78]
Diabetic Neuropathy; Diabetes mellitus - Neuromuscular Home Page
DIABETES: NEUROPATHIES & NEUROMUSCULAR DISORDERS · Disease onset: 7.5% · 25 years after onset: 50% · Overall: 30% · Similar or slightly higher in NIDDM (Type 2) vs.
[79]
Pathogenesis of Distal Symmetrical Polyneuropathy in Diabetes - PMC
Jul 19, 2022 · Distal symmetrical polyneuropathy (DSPN) is a serious complication of diabetes with a lifetime prevalence of more than 50% in people with ...
[80]
Epidemiology of Peripheral Neuropathy and Lower Extremity ... - NIH
Aug 27, 2019 · The prevalence of peripheral neuropathy is estimated to be between 6% and 51% among adults with diabetes depending on age, duration of diabetes, glucose ...
[81]
Guillain-Barré Syndrome
Jan 31, 2025 · In the most common type of GBS, called acute inflammatory demyelinating polyradiculoneuropathy (AIDP), the immune system damages the myelin ...
[82]
Guillain-Barre Syndrome - StatPearls - NCBI Bookshelf - NIH
Guillain-Barré syndrome (GBS) is a rare but serious post-infectious immune-mediated neuropathy. It results from the autoimmune destruction of nerves in the ...
[83]
Spinal Schwannoma; Analysis of 40 Cases - PMC - NIH
Spinal schwannomas account for about 25% of primary intradural spinal cord tumors in adults. There is no significant prevalence difference between males and ...
[84]
Spinal Nerves Schwannomas: Experience on 367 Cases—Historic ...
Solitary spinal nerve schwannomas or neurinomas are the most common nerve sheath tumors of the spine [1–4]. A male-to-female ratio of 1 : 1 has been reported, ...