Smelling TNT: Trends of the Terminal Nerve.

There is very little knowledge regarding the terminal nerve, from its implications in the involvement and pathogenesis of certain conditions, to its embryological origin. With this review, we try to summarize the most important evidence on the terminal nerve, aiming to clarify its anatomy and the various functions attributed to it, to better interpret its potential involvement in pathological processes. Recent studies have also suggested its potential role in the control of human reproductive functions and behaviors. It has been hypothesized that it plays a role in the unconscious perception of specific odors that influence autonomic and reproductive hormonal systems through the hypothalamic-pituitary-gonadal axis. We used the PubMed database and found different articles which were then selected independently by three authors. We found 166 articles, of which, after careful selection, only 21 were analyzed. The terminal nerve was always thought to be unimportant in our body. It was well studied in different types of animals, but few studies have been completed in humans. For this reason, its function remains unknown. Studies suggest a possible implication in olfaction due to the anatomical proximity with the olfactive nerve. Others suggest a more important role in reproduction and sexual behaviors. New emerging information suggests a possible role in Kallmann syndrome and COVID-19.

Acetylcholine Inhibits Spontaneous Firing Activity of Terminal Nerve GnRH Neurons in Medaka.

Vertebrates generally possess hypophysiotropic and non-hypophysiotropic gonadotropin releasing hormone (GnRH) neurons. The terminal nerve (TN) GnRH neurons are known to belong to the non-hypophysiotropic neurons and have been suggested to modulate sexual behaviors. These neurons show spontaneous pacemaker firing activity and release neuropeptides GnRH and neuropeptide FF. Since the spontaneous firing activities of peptidergic neurons, including GnRH neurons, are believed to play important roles in the release of neuropeptides, understanding the regulatory mechanisms of these spontaneous firing activities is important. Here, we analyzed firing activities of the TN-GnRH neurons in medaka during application of acetylcholine (ACh), which is one of the essential neuromodulators in the brain. Whole cell patch clamp recording of TN-GnRH neurons demonstrated that ACh induces hyperpolarization and inhibits their pacemaker firing. Electrophysiological analysis using an antagonist for acetylcholine receptors and in situ hybridization analysis showed that firing of TN-GnRH neurons is inhibited via M2-type muscarinic acetylcholine receptor. These findings, taken together with literature from several other fish species (including teleosts and elasmobranchs), indicate that ACh may generally play an inhibitory role in modulating spontaneous activities of TN-GnRH neurons and thereby sexual behaviors in fish.

Extensive apoptosis during the formation of the terminal nerve ganglion by olfactory placode-derived cells with distinct molecular markers.

The terminal nerve ganglion (TNG) is a well-known structure of the peripheral nervous system in cartilaginous and teleost fishes. It derives from the olfactory placode during embryonic development. While the differentiation and migration of gonadotropin releasing hormone (GnRH)-expressing neurons from the olfactory placode has been well documented, the TNG has been neglected in birds and mammals, and its development is less well described. Here we describe the formation of a ganglion-like structure from migratory olfactory placodal cells in chicken. The TNG is surrounded by neural crest cells, but in contrast to other cranial sensory ganglia, we observed no neural crest corridor, and olfactory unsheathing cells appear only after the onset of neuronal migration. We identified Isl1 and Lhx2 as two transcription factors that label neuronal subpopulations in the forming TNG, distinct from GnRH1+ cells, thereby revealing a diversity of cell types during the formation of the TNG. We also provide evidence for extensive apoptosis in the terminal nerve ganglion shortly after its formation, but not in other cranial sensory ganglia. Moreover, at later stages placode-derived neurons expressing GnRH1, Isl1 and/or Lhx2 become incorporated in the telencephalon. The integration of TNG neurons into the telencephalon together with the earlier widespread apoptosis in the TNG might be an explanation why the TNG in mammals and birds is much smaller compared to other vertebrates.

Clinical relevance of neurological evaluation in patients suffering urinary retention in the absence of subvesical obstruction.

PURPOSE: Clinical relevance of neurological evaluation in patients suffered urinary retention in the absence of subvesical obstruction. Determining whether (1) women complaining residual bladder volume without prolapse and obstruction always suffer pudendal nerve damage; (2) neurogenic damage can be linked to patients history/clinical examination; (3) therapy alters regarding to neurological findings; and (4) electromyography (EMG) of musculus sphincter ani externus (MSAE) can be omitted with electronically stimulated pudendal nerve latency (ESPL) as the standard investigation. METHODS: Women with urinary retention without ≥stage 2 prolapse or obstruction have neurological investigation including vaginally and anally pudendal terminal nerve latency (PTNL) (>2.4 ms considered abnormal) and EMG seen 7/2005-04/2010. RESULTS: (1) 148/180 (82.2%) suffered at least moderate neurogenic damage and (2) severe neurogenic damage occurs with urge odds ratio (OR) = 3.1 or age (OR = 3.2). Correlations: spasticity with therapy changes (OR = 11.1), latencies. (a) Anally: (i) right and peripheral neuropathy (PNP) (OR = 2.5), chemotherapy (OR = 5.0); (ii) left and PNP (OR = 3.9), chemotherapy (OR = 4.8); (iii) left or right with PNP (OR = 3.9), chemotherapy (OR = 6.8); and (iv) left and right with chemotherapy (OR = 5.0). (b) Vaginally: (i) right with age >60 (OR = 3.2), radical operation (OR = 10.6); (ii) left with diabetes mellitus (OR = 2.5); and (iii) left or right with age (OR = 3.3), radical operation (OR = 8.7). (3) 19.6% therapy changes (36 patients). (4) Neither EMG nor ESPL can be replaced one by another (p = 0.12 anal, p = 0.05 vaginal). CONCLUSION: Red flags are neurogenic damage, age >60, chemotherapy, PNP, radical operation or diabetes. In unclear situations, EMG and ESPL need to be performed to gain relevant information.

The neglected cranial nerve: nervus terminalis (cranial nerve N).

The nervus terminalis (NT; terminal nerve) was clearly identified as an additional cranial nerve in humans more than a century ago yet remains mostly undescribed in modern anatomy textbooks. The nerve is referred to as the nervus terminalis because in species initially examined its fibers were seen entering the brain in the region of the lamina terminalis. It has also been referred to as cranial nerve 0, but because there is no Roman symbol for zero, an N for the Latin word nulla is a better numerical designation. This nerve is very distinct in human fetuses and infants but also has been repeatedly identified in adult human brains. The NT fibers are unmyelinated and emanate from ganglia. The fibers pass through the cribriform plate medial to those of the olfactory nerve fila. The fibers end in the nasal mucosa and probably arise from autonomic/neuromodulatory as well as sensory neurons. The NT has been demonstrated to release luteinizing-releasing luteinizing hormone and is therefore thought to play a role in reproductive behavior. Based on the available evidence, the NT appears to be functional in adult humans and should be taught in medical schools and incorporated into anatomy/neuroanatomy textbooks.

Illuminating the terminal nerve: Uncovering the link between GnRH-1 neuron and olfactory development.

During embryonic development, the olfactory placode (OP) generates migratory neurons, including olfactory pioneer neurons, cells of the terminal nerve (TN), gonadotropin-releasing hormone-1 (GnRH-1) neurons, and other uncharacterized neurons. Pioneer neurons from the OP induce olfactory bulb (OB) morphogenesis. In mice, GnRH-1 neurons appear in the olfactory system around mid-gestation and migrate via the TN axons to different brain regions. The GnRH-1 neurons are crucial in controlling the hypothalamic-pituitary-gonadal axis. Kallmann syndrome is characterized by impaired olfactory system development, defective OBs, secretion of GnRH-1, and infertility. The precise mechanistic link between the olfactory system and GnRH-1 development remains unclear. Studies in humans and mice highlight the importance of the prokineticin-2/prokineticin-receptor-2 (Prokr2) signaling pathway in OB morphogenesis and GnRH-1 neuronal migration. Prokr2 loss-of-function mutations can cause Kallmann syndrome (KS), and hence the Prokr2 signaling pathway represents a unique model to decipher the olfactory/GnRH-1 connection. We discovered that Prokr2 is expressed in the TN neurons during the critical period of GnRH-1 neuron formation, migration, and induction of OB morphogenesis. Single-cell RNA sequencing identified that the TN is formed by neurons distinct from the olfactory neurons. The TN neurons express multiple genes associated with KS. Our study suggests that the aberrant development of pioneer/TN neurons might cause the KS spectrum.

Transient expression of NF200 by fibers in the nasal septum and rostral telencephalon of developing opossums (Monodelphis domestica).

Marsupials are born very immature and crawl on their mother's belly to attach to teats. Sensory information is required to guide the newborn and to induce attachment to the teat. Olfaction has been classically proposed to influence neonatal behaviors, but recent studies suggest that the central olfactory structures are too immature to account for them. In the newborn opossum, we previously described a fascicle of nerve fibers expressing neurofilament-200 (NF200, a marker of fiber maturity) from the olfactory bulbs to the rostral telencephalon. The course of these fibers is compatible with that of the terminal nerve that, during development, is characterized by the presence of neurons synthetizing gonadotropin hormones (GnRH). To evaluate if these fibers are related to the terminal nerve and if they play a role in precocious behaviors in opossums, we used immunohistochemistry against NF200 and GnRH. The results show that NF200-labeled fibers are present between P0 and P11, but do not reach much further caudally than the septal region. Only a few NF200-labeled fibers were found near the olfactory and vomeronasal epitheliums and they did not penetrate the olfactory bulbs. NF200-labeled fibers follow the same path as fibers labeled for GnRH. In contrast to the latter, NF200-labeled fibers are no longer visible at P15. These results suggest that these fibers are neither from the olfactory nor from the vomeronasal nerves but may be part of the terminal nerve. Their limited caudal extension does not support a role in the sensorimotor behaviors of the newborn opossum.

Multiple gonadotropin-releasing hormone systems in non-mammalian vertebrates: Ontogeny, anatomy, and physiology.

Three paralogous genes for gonadotropin-releasing hormone (GnRH; gnrh1, gnrh2, and gnrh3) and GnRH receptors exist in non-mammalian vertebrates. However, there are some vertebrate species in which one or two of these paralogous genes have become non-functional during evolution. The developmental migration of GnRH neurons in the brain is evolutionarily conserved in mammals, reptiles, birds, amphibians, and jawed teleost fish. The three GnRH paralogs have specific expression patterns in the brain and originate from multiple sites. In acanthopterygian teleosts (medaka, cichlid, etc.), the preoptic area (POA)-GnRH1 and terminal nerve (TN)-GnRH3 neuronal types originate from the olfactory regions. In other fish species (zebrafish, goldfish and salmon) with only two GnRH paralogs (GnRH2 and GnRH3), the TN- and POA-GnRH3 neuronal types share the same olfactory origin. However, the developmental origin of midbrain (MB)-GnRH2 neurons is debatable between mesencephalic or neural crest site. Each GnRH system has distinctive anatomical and physiological characteristics, and functions differently. The POA-GnRH1 neurons are hypophysiotropic in nature and function in the neuroendocrine control of reproduction. The non-hypophysiotropic GnRH2/GnRH3 neurons probably play neuromodulatory roles in metabolism (MB-GnRH2) and the control of motivational state for sexual behavior (TN-GnRH3).

Olfactory placode generates a diverse population of neurons expressing GnRH, somatostatin mRNA, neuropeptide Y, or calbindin in the chick forebrain.

The olfactory placode (OP) of vertebrates generates several classes of migrating cells, including hypothalamic gonadotropin-releasing hormone (GnRH)-producing neurons, which play essential roles in the reproduction system. Previous studies using OP cell labeling have demonstrated that OP-derived non-GnRH cells enter the developing forebrain; however, their final fates and phenotypes are less well understood. In chick embryos, a subpopulation of migratory cells from the OP that is distinct from GnRH neurons transiently expresses somatostatin (SS). We postulated that these cells are destined to develop into brain neurons. In this study, we examined the expression pattern of SS mRNA in the olfactory-forebrain region during development, as well as the destination of OP-derived migratory cells, including SS mRNA-expressing cells. Utilizing the Tol2 genomic integration system to induce long-term fluorescent protein expression in OP cells, we found that OP-derived migratory cells labeled at embryonic day (E) 3 resided in the olfactory nerve and medial forebrain at E17-19. A subpopulation of green fluorescent protein (GFP)-labeled GnRH neurons that remained in the olfactory nerve was considered to comprise terminal nerve neurons. In the forebrain, GFP-labeled cells showed a distribution pattern similar to that of GnRH neurons. A large proportion of GFP-labeled cells expressed the mature neuronal marker NeuN. Among the GFP-labeled cells, the percentage of GnRH neurons was low, while the remaining GnRH-negative neurons either expressed SS mRNA, neuropeptide Y, or calbindin D-28k or did not express any of them. These results indicate that a diverse population of OP-derived neuronal cells, other than GnRH neurons, integrates into the chick medial forebrain.

Development of the gonadotropin-releasing hormone system.

This review summarizes the current understanding of the development of the neuroendocrine gonadotropin-releasing hormone (GnRH) system, including discussion on open questions regarding (1) transcriptional regulation of the Gnrh1 gene; (2) prenatal development of the GnRH1 system in rodents and humans; and (3) paracrine and synaptic communication during migration of the GnRH cells.

The vomeronasal organ: History, development, morphology, and functional neuroanatomy.

The human vomeronasal organ (VNO) is an accessory olfactory organ located on the anteroinferior part of the nasal septum, 1.5-2.5cm from the nostrils. Its main role is pheromone reception and, through its anatomical connections with the central nervous system, especially parts of the hypothalamus, modulation of both social and sexual behavior, although these relations have been established only in nonprimates and very little is yet established for the structure and function of the human VNO. Morphologically, the human VNO is a pit or duct-shaped structure, comprised of three cellular layers-basal cells, neural cells with olfactory cell morphology and immunohistochemical phenotype, and ciliated respiratory epithelium. Medially and connected to the VNO, a small nerve fiber is found that runs longitudinally to the nasal septum and is considered by some to be a distant process of the Cranial Nerve 0 or terminal nerve. In addition to pheromone reception, the human VNO has also been associated with several pathological conditions, including sinus septi nasi, posttraumatic stress disorder, and ectopic olfactory esthesioblastoma.

Cranial nerve 13.

Contrary to popular belief, there are 13 cranial nerves. The thirteenth cranial nerve, commonly referred to as the nervus terminalis or terminal nerve, is a highly conserved multifaceted nerve found just above the olfactory bulbs in humans and most vertebrate species. In most forms its fibers course from the rostral portion of the brain to the olfactory and nasal epithelia. Although there are differing perspectives as to what constitutes this nerve, in most species GnRH-immunoreactive neurons appear to be its defining feature. The involvement of this trophic peptide, as well as the nerve's association with the development of the hypothalamic-pituitary-gonadal axis, suggest a primary role in reproductive development and, in humans, disorders such as Kallmann syndrome. In some species, this enigmatic nerve appears to influence sensory processing, sexual behavior, autonomic and vasomotor control, and pathogenic defense (via secretion of nitric oxide). In this review, we provide a general overview of what is known about this neglected cranial nerve, with the goal of informing neurologists and neuroscientists of its presence and the need for its further study.

Terminal Nerve GnRH3 Neurons Mediate Slow Avoidance of Carbon Dioxide in Larval Zebrafish.

Escape responses to threatening stimuli are vital for survival in all animal species. Larval zebrafish display fast escape responses when exposed to tactile, acoustic, and visual stimuli. However, their behavioral responses to chemosensory stimuli remain unknown. In this study, we found that carbon dioxide (CO2) induced a slow avoidance response, which was distinct from the touch-evoked fast escape response. We identified the gonadotropin-releasing hormone 3-expressing terminal nerve as the CO2 sensor in the nose. Wide-field calcium imaging revealed downstream CO2-activated ensembles of neurons along three distinct neural pathways, olfactory, trigeminal, and habenulo-interpeduncular, further reaching the reticulospinal neurons in the hindbrain. Ablation of the nose, terminal nerve, or trigeminal ganglion resulted in a dramatic decrease in CO2-evoked avoidance responses. These findings demonstrate that the terminal nerve-trigeminal system plays a pivotal role in triggering a slow chemosensory avoidance behavior in the larval zebrafish.

Effects of hand-transmitted vibration on fingertip terminal nerve: A meta-analysis / 环境与职业医学

Background Hand-transmitted vibration is one of the most common occupational hazards and is closely related to symptoms of fingertip terminal nerve damage. Objective To analyze the effects of hand-transmitted vibration on the terminal nerve of fingertips. Methods We systematically searched literature about the effects of hand-transmitted vibration on fingertip terminal nerve at home and abroad. The outcome index was the number (rate) of fingertip terminal nerve symptoms reported by the vibration group and the control group, such as finger numbness and finger tingling, and the search period was from database inception to December 2021. The quality of cross-sectional studies was assessed using the criteria recommended by the Agency for Healthcare Research and Quality (AHRQ), and the quality of cohort studies was assessed by the Newcastle-Ottawa Scale (NOS). NoteExpress 3.2 was used for literature management, and Excel 2003 was used for data collection and extraction. RevMan 5.4.1 software was used for statistical analysis, and random effect model was used to calculate the OR value of pooled effects and to draw forest plots. Subgroup analysis was carried out according to the working years with vibration exposure. At the same time, sensitivity analysis was performed after excluding studies with the largest weight and funnel plots were generated to evaluate publication bias. Results A total of 3619 articles were retrieved, and 39 articles were finally included, including 29 Chinese articles and 10 English articles; 36 cross-sectional studies and 3 cohort studies. In total, 8399 subjects were studied, including 5673 cases in the vibration exposure group and 2726 cases in the control group. Random effect model was used to merge the included literature. The results of meta-analysis showed that compared with the control group, hand-transmitted vibration was significantly associated with the self-reported occurrence of finger numbness (OR=8.29, 95%CI: 5.43-12.66), finger tingling (OR=7.50, 95%CI: 4.78-11.77), finger swelling (OR=8.25, 95%CI: 4.06-16.76), finger stiffness (OR=10.71, 95%CI: 3.60-31.87), finger trembling (OR=5.11, 95%CI: 2.60-10.04), hand weakness (OR=11.05, 95%CI: 3.98-30.68), hand sweating (OR=2.70, 95%CI: 1.64-4.43), hand coldness (OR=3.54, 95%CI: 2.42-5.18) (P<0.01). The subgroup analysis showed that the odds ratios of both finger numbness and finger tingling increased in the early and middle stages of vibration exposure (<5 years and 5-10 years of exposure duration）(finger numbness: OR=11.11, 19.07; finger tingling: OR=4.70, 16.55, respectively)(P<0.01), and decreased in the late stage of vibration exposure (10-15 years and ≥15 years of exposure duration) (finger numbness: OR=9.57, 2.30; finger tingling: OR=5.71, 6.00, respectively) (P<0.01). The results of sensitivity analysis showed a stable pooled effect (OR=13.96, 95%CI: 4.85-40.13, Z=4.89, P<0.01). The funnel plot results showed positive publication bias. Conclusion Occupational exposure to hand-transmitted vibration can cause finger numbness, finger tingling, finger swelling, finger stiffness, finger trembling, hand weakness, hand sweating, and hand coldness.

Organization of alpha-transducin immunoreactive system in the brain and retina of larval and young adult Sea Lamprey (Petromyzon marinus), and their relationship with other neural systems.

We employed an anti-transducin antibody (Gαt-S), in combination with other markers, to characterize the Gαt-S-immunoreactive (ir) system in the CNS of the sea lamprey, Petromyzon marinus. Gαt-S immunoreactivity was observed in some neuronal populations and numerous fibers distributed throughout the brain. Double Gαt-S- and opsin-ir neurons (putative photoreceptors) are distributed in the hypothalamus (postoptic commissure nucleus, dorsal and ventral hypothalamus) and caudal diencephalon, confirming results of García-Fernández et al. (Cell and Tissue Research, 288, 267-278, 1997). Singly Gαt-S-ir cells were observed in the midbrain and hindbrain, increasing the known populations. Our results reveal for the first time in vertebrates the extensive innervation of many brain regions and the spinal cord by Gαt-S-ir fibers. The Gαt-S innervation of the habenula is very selective, fibers densely innervating the lamprey homologue of the mammalian medial nucleus (Stephenson-Jones et al., Proceedings of the National Academy of Sciences of the United States of America, 109, E164-E173, 2012), but not the lateral nucleus homologue. The lamprey neurohypophysis was not innervated by Gαt-S-ir fibers. We also analyzed by double immunofluorescence the relation of this system with other systems. A dopaminergic marker (TH), serotonin (5-HT) or GABA do not co-localize with Gαt-S-ir neurons although codistribution of fibers was observed. Codistribution of Gαt-S-ir fibers and isolectin-labeled extrabulbar primary olfactory fibers was observed in the striatum and hypothalamus. Neurobiotin retrograde transport from the spinal cord combined with immunofluorescence revealed spinal-projecting Gαt-S-ir reticular neurons in the caudal hindbrain. Present results in an ancient vertebrate reveal for the first time a collection of brain targets of Gαt-S-ir neurons, suggesting they might mediate non-visual modulation by light in many systems.

Olfacto-retinalis pathway in Austrolebias charrua fishes: a neuronal tracer study.

The olfacto-retinal centrifugal system, a constant component of the central nervous system that appears to exist in all vertebrate groups, is part of the terminal nerve (TN) complex. TN allows the integration of different sensory modalities, and its anatomic variability may have functional and evolutionary significance. We propose that the olfacto-retinal branch of TN is an important anatomical link that allows the functional interaction between olfactory and visual systems in Austrolebias. By injecting three different neuronal tracers (biocytin, horseradish peroxidase, and 1,1'-dioctadecyl-3,3,3',3'tetramethyl-indocarbocyanine perchlorate (DiI)) in the left eye of Austrolebias charrua fishes, we identified the olfacto-retinal branch of TN and related neuronal somas that were differentiable by location, shape, and size. The olfacto-retinal TN branch is composed of numerous thin axons that run ventrally along the olfactory bulb (OB) and telencephalic lobes, and appears to originate from a group of many small monopolar neurons located in the rostral portion of both the ipsi- and contralateral OB (referred to as region 1). Labeled cells were found in two other regions: bipolar and multipolar neurons in the transition between the OB and telencephalic lobes (region 2) and two other groups in the preoptic/pretectal area (region 3). In this last region, the most rostral group is constituted by monopolar pear-shaped neurons and may belong to the septo-preoptic TN complex. The second group, putatively located in the pretectal region, is formed by pseudounipolar neurons and coincides with a conserved vertebrate nucleus of the centrifugal retinal system not involved in the TN complex. The found that connections between the olfactory and visual systems via the olfacto-retinal TN branch suggest an early interaction between these sensory modalities, and contribute to the identification of their currently unknown circuital organization.

Spinal Nerve Compositions of the Terminal Branches of the Lumbosacral Plexus / 체질인류학회지

The purpose of this study was to classify the spinal nerve compositions of the terminal branches of the lumbosacral plexus, providing data of their participating quantities. Twenty-five sides of the lumbosacral plexus extracted from Korean adult cadavers were used in this study. The iliohypogastric nerve was mostly arisen from L1 (88.2%, thickness L1 0.7 mm). The ilioinguinal nerve was arisen from only L1 (100%, thickness L1 0.6 mm). The genitofemoral nerve was commonly arisen from L1 and L2 (62.5%, thickness L1 0.6 mm, L2 0.7 mm). The lateral femoral cutaneous nerve was classified into 4 types, and the most common type was that L2 and L3 composed this nerve (56.0%, thickness L2 0.8 mm, L3 0.4 mm). The femoral nerve was classified into 2 types, and it was usually composed of L2, L3 and L4 (88.0%, thickness L2 1.4 mm, L3 2.7 mm, L4 2.3 mm). The obturator nerve was arisen from L2, L3 and L4 in all cases (100%, thickness L2 0.5 mm, L3 1.3 mm, L4 1.1 mm). The common fibular component of sciatic nerve was mostly arisen from L4, L5, S1 and S2 (84.0%, thickness L4 0.9 mm, L5 2.0 mm, S1 2.1 mm, S2 1.2 mm). The tibial component of sciatic nerve was mainly arisen from L4, L5, S1 and S2 (96.0%, thickness L4 0.9 mm, L5 1.9 mm, S1 2.2 mm, S2 1.9 mm). The superior gluteal nerve was commonly derived from L4, L5 and S1 (56.0%, thickness L4 0.7 mm, L5 1.1 mm, S1 0.9 mm). The inferior gluteal nerve was comprised of L5, S1 and S2 in several cases (54.2%, thickness L5 0.9 mm, S1 1.3 mm, S2 0.8 mm). The posterior femoral cutaneous nerve was composed of S1 and S2 in higher freqeuncy (40.0%, thickness S1 0.9 mm, S2 1.0 mm, S3 0.8 mm). The perforating cutaneous nerve was arisen from S2 and S3 in higher frequency (56.0%, thickness S1 0.7 mm, S2 0.9 mm, S3 1.1 mm). The pudendal nerve was derived from S3 in many cases (52.9%, thickness S3 1.5 mm). These anatomical results may be helpful to predict the spinal nerve root lesions of the lumbosacral plexus.