Temperature signals from skin and spinal cord converging on spinothalamic neurons

Summary In anesthetized, artificially ventilated cats with spinal transection at C₂, the temperature of the thoracolumbar spinal cord was varied by means of a water perfused thermode located in the peridural space of the vertebral canal. Single unit activity was recorded from the anterolateral tracts at C₃–C₅. As in a preceding investigation, units were found which were activated either by spinal cord cooling (spinal cold units) or by spinal cord heating (spinal warm units).In addition, the temperature of the skin of the trunk and the hind legs was varied by means of a water perfused coat in order to find out, whether spinal cold and warm units were also influenced by the signals of the cutaneous thermoreceptors. 11 spinal cold units and 10 spinal warm units were investigated in this way. With only one exception, they were found to be influenced by the skin temperature variations.Skin cooling below 38°C led to an increase of activity in 9 investigated spinal cold units. Skin cooling in 8 spinal warm units had, on the average, a negligible effect, although in some units a slight decrease of activity was observed.In several experiments the responses of spinal cold and warm units to skin heating above 40°C were investigated. 4 spinal cold units tested in this way responded to skin heating with an increase of activity. In 9 spinal warm units, activity was either depressed or increased by skin heating; one unit remained unaffected.     

Thermoregulatory behaviour after repetitive cooling of the preoptic area and of the spinal cord in the rat

Summary The thermoregulatory behaviour of 6 rats was studied during exposure to cold and warm ambient temperatures after either the preoptic area or the cervical spinal cord had been intermittently cooled for an average of 130 h. The precooled animals worked more for heat in cold environments and less for cool air in a warm environment than the control animals. This behaviour, probably due to a decreased ability of the precooled animals to retain heat, suggests that the precooled animals were not fully adapted to cold.     

Influence de stimulations thermiques de la moëlle épinière sur le comportement thermorégulateur du chien

Summary Thermodes were chronically implanted in the epidural space of 3 dogs. The dogs had learned to turn on a fan or infra-red lamps by making a voluntary head movement, in a climatic chamber. Their thermoregulatory behavior was therefore quantitatively measured.Thermal stimulation of the spinal cord was achieved by perfusing water through the spinal thermode.In a warm environment, spinal cord heating produced an increased behavioral fresh air request. On the other hand, spinal cord cooling had no effect upon behavioral fresh air request.In a cold environment, results obtained with one dog showed a decreased behavioral infra-red request during spinal cord heating. Again, thermoregulatory behavior was not changed by spinal cord cooling.These experiments demonstrate the existence of a warm sensitivity in the spinal cord capable of triggering thermoregulatory behavioral response. No evidence was found for a corresponding cold sensitivity.

Travail effectué grâce à l'aide financière du Centre National de la Recherche Scientifique (C.N.R.S.) et de l'institut National de la Santé et de la Recherche Médicale (I.N.S.E.R.M.).     

The interaction between cutaneous and spinal therman inputs in the control of oxygen consumption in the rat.

1. The effect of thermal stimulation of the spinal cord on the rate of oxygen consumption was studied in five unanaesthetized rats during exposure to various ambient temperatures. 2. In a warm environment, cooling the spinal cord had no effect on the rate of oxygen consumption but in thermoneutral and cold environments the rate of oxygen consumption increased proportionally to the intensity of spinal cooling. Heating the spinal cord decreased the level of oxygen consumption and, if intense enough, suppressed the thermoregulatory increase in metabolic rate. 3. It is concluded that, in the control of oxygen consumption in the rat, the afferent signals from thermal sensors in the spinal cord and skin are added.     

Sensory transmission of spinal heat and cold sensitivity in ascending spinal neurons

Summary In anesthetized cats, mostly spinalized at C₁/C₂, the thoracic and lumbar sections of the vertebral canal were selectively heated or cooled. Single unit activity was recorded with steel microelectrodes from the spinal cord at the level of C₂ to C₄. The positions of the electrode tips were determined by micromarking.The existence of two groups of temperature dependent ascending spinal units was confirmed. One group of units was activated by spinal cord cooling below normal body temperature. The other group was activated by spinal cord heating. No temperature dependent neurons were found, so far, exhibiting maximum discharge rates at normal body temperature. A roughly proportional relation between discharge rate and vertebral canal temperature seemed to exist in both heat sensitive and cold sensitive units within a limited range of spinal hyperthermia or hypothermia respectively. Part of the units exhibited dynamic responses to changes of vertebral canal temperature in addition to their static responses.As determined by micromarking, heat sensitive and cold sensitive ascending spinal units were conducted in the anterolateral tracts. Both types of units were observed also under neuromuscular blockage. It is concluded that the temperature dependent ascending spinal neurons are transmitting signals from basically afferent spinal thermosensitive structures existing as two functionally different sets, one heat sensitive and one cold sensitive.     

The influence of body core temperature and peripheral temperatures on oxygen consumption in the pig

1. The rate of oxygen consumption was measured in young pigs exposed to different ambient temperatures and the effect on metabolic rate of changing the temperature of thermodes implanted in the hypothalamus and over the spinal cord was determined. In some experiments the temperature of the skin over the trunk was changed by means of a water-perfused coat.2. Cooling the hypothalamus or the spinal cord in a warm ambient did not change the rate of oxygen consumption. At a thermoneutral ambient temperature, cooling either thermode increased oxygen consumption. In a cold environment, cooling either thermode increased the rate of oxygen consumption more than at a thermoneutral temperature. The increase in the rate of oxygen consumption was greatest during cooling of the spinal cord and it appeared that the pigs also shivered more violently. Heating either thermode tended to decrease oxygen consumption in a cold environment.3. In pigs with thermodes both in the hypothalamus and over the spinal cord, cooling both thermodes was accompanied by a greater increase in oxygen consumption than cooling either thermode alone. The increase in oxygen consumption on cooling one thermode could be reduced by heating the other.4. The skin temperature (fixed by the water perfused coat, or the ambient temperature) at which the rate of oxygen consumption increased, was lowered during heating of the thermodes, but the rate of increase in oxygen consumption appeared not to change as a function of falling skin or ambient temperature.     

The influence of deep body temperatures and skin temperatures on respiratory frequency in the pig

1. The influences on respiratory frequency of ambient temperature, the temperature of the skin, the temperature and humidity of the inspired air, hypothalamic temperature, the temperature of the spinal cord, rectal temperature and some temperatures in the abdomen have been studied in the pig.2. At a constant ambient temperature the effect on respiratory frequency of heating a thermode in the hypothalamus was modified by the temperature of the skin of the trunk which was varied independently by means of a temperature-controlled coat. A cold skin inhibited panting; a warm skin enhanced panting. The effect of heating a thermode over the spinal cord was similarly modified by skin temperatures.3. Simultaneous heating of thermodes in the hypothalamus and spinal cord increased respiratory frequency more than heating either alone, and in a warm environment the rectal temperature influenced the extent to which respiratory frequency increased on heating the thermodes.4. Cooling the thermodes decreased respiratory frequency in a warm environment and the cooling of one thermode enhanced the effect of cooling the other.5. At a constant trunk skin temperature the effect on respiratory frequency of heating the thermode in the hypothalamus depended on ambient temperature.6. Changing the temperature of thermodes in the abdomen did not affect respiration nor was there any evidence that the temperature and humidity of the inspired air had a direct effect on respiration.     

Formation of a specific antigen in spinal cord synapses of rats with local tetanus

Rabbit antisera against various subcellular fractions of spinal cord tissue of rats with local tetanus and reactive with the appropriate antigens in the complement fixation test were obtained. Antibodies reacting specifically with synaptosomes and synaptic membranes isolated from the “tetanus” spinal cord were found in antisera against synaptosomes of the “tetanus” spinal cord after exhaustion with a crude fraction of normal spinal cord mitochondria.     

鼠脊髓中央管接触脑脊液神经元的扫描电镜观察

本作者对4例大白鼠脊髓中央管壁进行了表面扫描电镜观察。结果观察到许多披有静纤毛或动纤毛的树突终末,尚发现一些轴突终末,这些皆属接触脑脊液神经元。在鼠脊髓中央管观察到轴突终末迄今未见文献报道。这些轴突终末可能是脊髓接触脑脊液神经元分泌物质的释放部位,所分泌的生物活性物质可通过脑脊液影响蛛网膜下腔的血管,而调节血流,进而影响细胞外液和/或脑脊液。     

Cellular organization of the central canal ependymal zone,a niche of latent neural stem cells in the adult mammalian spinal cord

A stem cell's microenvironment, or “niche,” is a critical regulator of its behaviour. In the adult mammalian spinal cord, central canal ependymal cells possess latent neural stem cell properties, but the ependymal cell niche has not yet been described. Here, we identify important similarities and differences between the central canal ependymal zone and the forebrain subventricular zone (SVZ), a well-characterized niche of neural stem cells. First, direct immunohistochemical comparison of the spinal cord ependymal zone and the forebrain SVZ revealed distinct patterns of neural precursor marker expression. In particular, ependymal cells in the spinal cord were found to be bordered by a previously uncharacterized sub-ependymal layer, which is relatively less elaborate than that of the SVZ and comprised of small numbers of astrocytes, oligodendrocyte progenitors and neurons. Cell proliferation surrounding the central canal occurs in close association with blood vessels, but unlike in the SVZ, involves mainly ependymal rather than sub-ependymal cells. These proliferating ependymal cells typically self-renew rather than produce transit-amplifying progenitors, as they generate doublets of progeny that remain within the ependymal layer and show no evidence of a lineage relationship to sub-ependymal cells. Interestingly, the dorsal pole of the central canal was found to possess a sub-population of tanycyte-like cells that express markers of both ependymal cells and neural precursors, and their presence correlates with higher numbers of dorsally proliferating ependymal cells. Together, these data identify key features of the spinal cord ependymal cell niche, and suggest that dorsal ependymal cells possess the potential for stem cell activity. This work provides a foundation for future studies aimed at understanding ependymal cell regulation under normal and pathological conditions.     

基于病理“金标准”标记脊髓损伤慢性期MRI图像坏死区域的方法

脊髓损伤慢性期胶质瘢痕及其所包绕的囊腔所构成的脊髓坏死区域在磁共振成像（MRI）中形态各异，边界模糊。针对单纯根据图像无法准确识别脊髓坏死区域这一问题，提出一种基于病理切片“金标准”来标记MRI图像实际坏死区域的方法。双边滤波去噪并刚体配准脊髓损伤慢性期的多模态MRI图像，使用Snake模型进行脊髓的分离，并利用双三次插值法对脊髓进行拉直。采用双树复小波变换融合不同模态的图像后，基于病理切片的胶质瘢痕及囊腔区域与MRI图像的脊髓坏死区域具有空间相对位置一致性的特点，建立从脊髓病理切片到MRI图像的空间映射关系，最终实现MRI图像中实际坏死区域的标记。以圆度和偏心率作为形状评价指标，对本方法标记的MRI坏死区域与病理切片“金标准”结果进行对比，相似度分别达到了0.93±0.03和0.97±0.02。结果表明，应用本方法构建的映射关系能较为准确、客观地标记MRI图像的实际坏死区域，为后期计算机自动识别与分割MRI坏死区域奠定基础。     

Responses of spinal cord neurons to systematic changes in hindlimb skin temperatures in cats and primates.

Single-neuron recordings were made from the lumbar spinal cords of cats and squirrel monkeys. Recording sites were distributed throughout the dorsal horn and included Rexed's laminae I and III-VI in both species and laminae VII-VIII in cats. Activity was studied during systematic changes in skin temperature over the range of 15-49 degress C; this encompasses the perceptions of innocuous cooling and warming plus the initial stages of noxious heating. The experiment included studies in which the thermal stimulus was changed from various preadapting temperatures. In all cases, the sensitivity of an individual neuron to changes in skin temperature was associated with responses to various intensities of tactile stimulation which, for some neurons, could range from low to painful pressures. More than two-thirds of the neurons excited by innocuous temperature changes discharged to both cooling and warming, although the thresholds were much lower for cold temperature differecnes (less than or equal to 2 degrees C for cold steps as compared with more than 6 degrees C for warm steps). However, many neurons only responded to extreme cooling or, more frequently, noxious heating. The temperature response relationships of many neurons during cooling was best described in reference to specific cold-receptor activity because the discharge rates declined at extremely cold temperatures and because the slopes of the temperature-response functions were nearly identical when studied with different adapting temperatures. The responses of certain slowly adapting mechanoreceptors was considered in describing some of the spinal cord activity during extreme cooling. The responses to hot temperatures were attributed to activity in various receptors, including especially polymodal receptors. Activity during innocuous warming was ascribed to one population of peripheral warm receptors that do not show maximal static activity during innocuous warm stimuli. The significance of the extensive convergence in the spinal cord from mechanoreceptors and thermoreceptors was discussed in relation to thermal perception and the complexity of the information transmitted by the spinothalamic tract.     

Effects of various ambient temperatures and of heating and cooling the hypothalamus and cervical spinal cord on antidiuretic hormone secretion and urinary osmolality in pigs.

1. Plasma ADH concentration, urinary and plasma osmolality and haematocrit were measured in young pigs placed in cold, thermoneutral, warm and hot ambient temperatures. In some experiments a thermode placed in the hypothalamus or over the cervical spinal cord was heated or cooled at various ambient temperatures. 2. Plasma ADH concentration remained at a low level (0-5--5 muu. ml.-1) over 2 hr or 3 hr periods when the pigs were in cold, thermoneutral or warm ambient temperatures. A hot environment, which caused a marked rise in the pigs' rectal temperature, was associated with a large rise in plasma ADH level. 3. The rise in plasma ADH level which occurred during an increase in body temperature was consistently and completely suppressed by simultaneous cooling of the thermode in the pre-optic region to 5 to 10 degrees C. When the thermode was in the region of the supraoptic nucleus the rise in ADH was only partly suppressed, and when it was over the cervical cord it was only sometimes suppressed. 4. Cooling the thermodes in any position at a cold or thermoneutral ambient temperature, or heating them at a thermoneutral or warm ambient temperature, caused no consistent change in ADH. 5. A diuresis, with a urinary flow-rate of at most 1 ml. min-1 and minimal urinary osmolality of 53 m-osmole kg-1, was observed on only three occasions, twice during cooling of a thermode in the hypothalamus and once after the end of a period when the thermode was heated. In each case, the plasma ADH was less than 2 muu. ml.-1. 6. A slight rise of haematocrit in cold ambient conditions and a slight fall in the warm were observed. Otherwise changes in haematocrit were trivial, and a shift of water between vascular system and interstitium could not be invoked to account for changes in ADH levels. Observed variation of plasma osmolality was also slight.     

Immunocytochemical localization of zinc transporter 3 in the ependyma of the mouse spinal cord

We report, for the first time, the light microscopical and ultrastructural appearance of ZnT3-immunoreactivities in the ependymal cells of the central canal of the mouse spinal cord. Light microscopy revealed the presence of ZnT3-immunoreactive (Ir) ependymal cells in 1 microm thick epon sections stained by the ABC method. The ZnT3-Ir cells were observed at all levels of the spinal cord, but were a little more numerous in lumbosacral segments than in cervicothoracic segments. The ZnT3-Ir cells had large, ovoid nuclei with abundant cytoplasm, and protruded into the lumen of the central canal. Our ultrastructural findings suggest that the ZnT3-Ir ependymal cells possess secretory activity directed towards the central canal. We propose that they may play a role in the trans-ependymal mechanism responsible for zinc homeostasis between cerebrospinal fluid and the central area of the gray matter.     

The locomotion of the low spinal cat. II. Interlimb coordination

The interaction of the two hindlimbs were investigated by an analysis of the muscular activity and the movements in 14 chronic spinal kittens during treadmill locomotion (i.e. in kittens subjected to a transection of the spinal cord (Th_10–12) one or two weeks after birth). At low speed the limbs were alternating (walk or trot). At higher they were activated more simultaneous, as during gallop. The two limbs could walk at different velocities, as during walking in a circle, when the two belts of the treadmill were driven at different speeds. The duration of the support phases was mainly influenced by the speed of the belt on which the limb was walking. The limbs could still maintain a common rhythm up to a two or three fold speed difference, as the flexion or the first extension phase of the limb walking on the “fast” belt was prolonged and the flexion phase of the “slow limb” was shortened. At extreme speed differences the limb on the “fast belt” performed 2, 3 and even 4 steps during one stepcycle of the “slow limb”. The placement of the feet was found to maintain the most stable relationship during alternating gaits at different speed differences. It is concluded that all phases of the step cycle are modifiable and that there are several mechanisms coordinating the limbs within the spinal cord.     

间充质干细胞对脊髓损伤治疗的研究进展

文题释义：脊髓损伤：由于外界直接或间接因素导致的脊髓相应节段损伤,损伤后出现各种运动、感觉和括约肌功能障碍、肌张力异常及病理反射等相应改变。如何使受损的神经结构进行再生和修复,从而促进神经功能的恢复仍是当前治疗的难点和研究的热点。脊髓损伤主要表现在急性期出现脊髓损伤处神经元的坏死、少突胶质细胞的凋亡、髓鞘的崩解、神经束变性坏死以引发的炎症反应等。对于脊髓损伤的治疗往往是通过对以上几方面的修复来实现的。 间充质干细胞移植治疗脊髓损伤的作用机制：间充质干细胞以其高度的可塑性、在一定条件下可向神经细胞诱导分化等优点使其可以在不同个体间移植。间充质干细胞体内移植后通过分化为神经细胞替代已损伤的神经元;间充质干细胞进入病变区后通过旁分泌释放大量的抗炎因子、细胞因子、生长因子及细胞黏附因子来改变脊髓损伤微环境;间充质干细胞能产生多种细胞外基质,促进神经元轴突再生、髓鞘化并可诱导细胞方向性生长和迁移等。   摘要背景：脊髓损伤是人类致残率最高的疾病之一,由于脊髓轴突再生能力有限,恢复难度大,常导致严重的神经后遗症,对脊髓损伤治疗方法的探索已成为研究热点。随着生物学及分子生物学研究的不断深入,研究发现间充质干细胞治疗脊髓损伤表现出巨大的潜力,为脊髓损伤的修复带来了曙光。 目的：综述间充质干细胞对于脊髓损伤的治疗作用、性质、应用、局限性及发展前景。 方法：检索PubMed、Web of Science数据库及万方、CNKI中国期刊全文数据库收录的间充质干细胞治疗脊髓损伤的相关文章,英文检索词为“spinal cord injury,mesenchymal stem cell”,中文检索词为“脊髓损伤,间充质干细胞”,按纳入和排除标准共纳入文献85篇进行归纳总结。结果与结论：间充质干细胞通过多种作用机制修复脊髓损伤,如间充质干细胞体内移植后通过分化为神经细胞替代已损伤的神经元;通过旁分泌机制分泌各种营养物质来改变脊髓损伤微环境的变化;同时间充质干细胞产生多种细胞外基质,为再生轴突提供支持物,促进神经元轴突再生。虽然在基础实验中间充质干细胞治疗脊髓损伤能起到较好的疗效,但间充质干细胞在临床中的应用却差强人意,还需要更深入地探索间充质干细胞对于脊髓损伤的作用机制。 ORCID: 0000-0002-3216-3301(史旭) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Parabronchial oxygen extraction in ducks during selective cooling of the spinal cord

Pekin ducks Anas platyrhynchos were chronically equipped with thermodes in the vertebral canal. Metabolic heat production, parabronchial oxygen extraction, vertebral canal temperature and body temperature were measured simultaneously before and during spinal cooling, at ambient temperatures ranging from 6 to 25 degrees C. Lowering vertebral canal temperature from 41.4 +/- 0.2 degrees C to 35.9 +/- 0.6 degrees C gave a mean increase in metabolic heat production of 1.54 +/- 0.26 W kg-1. Even though the spinal cooling had a clear metabolic effect, there was no concomitant change in parabronchial oxygen extraction. It is concluded that the thermosensitive structures residing in the spinal cord are not involved in the regulation of parabronchial gas exchange. The increase in parabronchial oxygen extraction, which is reported during cold exposure in birds, may therefore be induced by thermal inputs from peripheral thermoreceptors.     

Cytotoxic CD8+ T cell ablation enhances the capacity of regulatory T cells to delay viral elimination in Theiler's murine encephalomyelitis

Theiler's murine encephalomyelitis (TME) of susceptible mouse strains is a commonly used infectious animal model for multiple sclerosis. The study aim was to test the hypothesis whether cytotoxic T cell responses account for the limited impact of regulatory T cells on antiviral immunity in TME virus‐induced demyelinating disease (TMEV‐IDD) resistant C57BL/6 mice. TME virus‐infected C57BL/6 mice were treated with (i) interleukin‐2/‐anti‐interleukin‐2‐antibody‐complexes to expand regulatory T cells (“Treg‐expansion”), (ii) anti‐CD8‐antibodies to deplete cytotoxic T cells (“CD8‐depletion”) or (iii) with a combination of Treg‐expansion and CD8‐depletion (“combined treatment”) prior to infection. Results showed that “combined treatment”, but neither sole “Treg‐expansion” nor “CD8‐depletion,” leads to sustained hippocampal infection and virus spread to the spinal cord in C57BL/6 mice. Prolonged infection reduces myelin basic protein expression in the spinal cord together with increased accumulation of β‐amyloid precursor protein in axons, characteristic of myelin loss and axonal damage, respectively. Chronic spinal cord infection upon “combined treatment” was also associated with increased T and B cell recruitment, accumulation of CD107b⁺ microglia/macrophages and enhanced mRNA expression of interleukin (IL)‐1α, IL‐10 and tumor necrosis factor α. In conclusion, data revealed that the suppressive capacity of Treg on viral elimination is efficiently boosted by CD8‐depletion, which renders C57BL/6 mice susceptible to develop chronic neuroinfection and TMEV‐IDD.     

Development and distribution of enkephalin-immunoreactive elements in the chicken spinal cord

The development and distribution of methionine-enkephalin-immunoreactive elements were studied in the chicken spinal cord with the indirect immunofluorescence method. Methionine-enkephalin-like immunoreactivity was first detected in the chick spinal cord at embryonic stages 29-30 (incubation day 6). Before stage 35 (day 9), it was mainly observed in fibres almost throughout the white matter. Subsequently, fibres containing the peptide appeared in the ventral half of the gray matter, but mostly in the lateral portion of the neck of the dorsal horn. From stage 40 (day 13 or 14), fibres were especially noticed in laminae 1 and 2, and in the area dorsal to the central canal. In particular, many enkephalin-immunoreactive perikarya were observed in several spinal areas during this period. Such a distribution of both enkephalin-immunoreactive fibres and perikarya remained visible at later embryonic stages, but labelled cells gradually decreased in number and disappeared after hatching. With colchicine treatment, however, a similar distribution of the peptide was found in the spinal cord of adult chickens. As in the embryo, enkephalin-immunoreactive perikarya were mainly observed in the lateral portion of the neck of the dorsal horn, in lamina 1, and in the nucleus of the dorsolateral funiculus throughout the spinal cord. At the thoracic level, many were also located ventral to the central canal. Enkephalin-immunoreactive fibres increased notably in the gray matter of adult chickens. They mainly occurred in laminae 1 and 2, in the lateral portion of the neck of the dorsal horn, and in the area around, especially dorsal to, the central canal. In contrast, enkephalin-immunoreactive fibres decreased in the white matter and they were mainly observed in the dorsolateral funiculus, in Lissauer's tract, and in the lateral funiculus adjacent to the gray. The distribution of enkephalin-immunoreactive fibres was generally comparable at all spinal levels examined. In addition, examination of post-hatched chickens showed virtually the same results as in the adult.     

Observations on the caudal end of the spinal cord

The development of the structural pattern of the lower sacral and coccygeal segments of the spinal cord in human, rabbit and monkey embryos and fetuses has been studied. The changes observed in serial sections from above downward are outlined, beginning with typical sections through the lower sacral cord. Among the changes, other than diminution in size of the spinal cord and reduction in size of the lower spinal nerves, there is a gradual disappearance of the posterior funiculus. As this occurs the gray matter appears to spread dorsally and the central canal widens. The gray matter becomes reduced in size and the lateral funiculus extends farther dorsally. A little lower down, the gray matter of the alar plate is reduced further in size and there is corresponding enlargement of the central canal. This enlargement constitutes the terminal ventricle. The spinal cord rapidly becomes smaller as both the fibers and the gray matter are diminished. In some specimens, fibers decussate dorsal to the lower end of the terminal ventricle. Little remains of the lower end of the spinal cord except the ependymal wall of the central canal and the surrounding fiber bundles. The shape and size of the lower end of the central canal is subject to variations. In the lower part of the spinal cord a longitudinal bundle on each side is formed by fiber contributions from the anterior horn cells in the basal plates. This bundle contributes fibers to the fifth sacral and the first and second coccygeal nerves. It is designated the sacrococcygeal fasciculus.