214:
classification as "motor neurons." Essentially, motor neurons, also known as motoneurons, are made up of a variety of intricate, finely tuned circuits found throughout the body that innervate effector muscles and glands to enable both voluntary and involuntary motions. Two motor neurons come together to form a two-neuron circuit. While lower motor neurons start in the spinal cord and go to innervate muscles and glands all throughout the body, upper motor neurons originate in the cerebral cortex and travel to the brain stem or spinal cord. It is essential to comprehend the distinctions between upper and lower motor neurons as well as the routes they follow in order to effectively detect these neuronal injuries and localise the lesions.
40:
1042:. Fly motor neurons vary by over 100X in the total number of input synapses. However, each motor neuron gets similar fractions of its synapses from each premotor source: ~70% from neurons within the VNC, ~10% from descending neurons, ~3% from sensory neurons, and ~6% from VNC neurons that also send a process up to the brain. The remaining 10% of synapses come from neuronal fragments that are unidentified by current image segmentation algorithms and require additional manual segmentation to measure.
378:
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Fast fatiguing (FF) motor units stimulate larger muscle groups, which apply large amounts of force but fatigue very quickly. They are used for tasks that require large brief bursts of energy, such as jumping or running. They gain their energy via glycolytic means and hence do not require oxygen. They
213:
Although the word "motor neuron" suggests that there is a single kind of neuron that controls movement, this is not the case. Indeed, upper and lower motor neurons—which differ greatly in their origins, synapse locations, routes, neurotransmitters, and lesion characteristics—are included in the same
931:
arrive before the end of the twitch. The twitches thus superimpose on one another, leading to a force greater than that of a single twitch. A tetanic contraction is caused by constant, very high frequency stimulation - the action potentials come at such a rapid rate that individual twitches are
651:
innervate intrafusal muscle fibers found within the muscle spindle. They regulate the sensitivity of the spindle to muscle stretching. With activation of gamma neurons, intrafusal muscle fibers contract so that only a small stretch is required to activate spindle sensory neurons and the stretch
598:
Slow (S) motor units stimulate small muscle fibers, which contract very slowly and provide small amounts of energy but are very resistant to fatigue, so they are used to sustain muscular contraction, such as keeping the body upright. They gain their energy via oxidative means and hence require
505:
are those that originate in the spinal cord and directly or indirectly innervate effector targets. The target of these neurons varies, but in the somatic nervous system the target will be some sort of muscle fiber. There are three primary categories of lower motor neurons, which can be further
954:
found within the motor end plate. Once two acetylcholine receptors have been bound, an ion channel is opened and sodium ions are allowed to flow into the cell. The influx of sodium into the cell causes depolarization and triggers a muscle action potential. T tubules of the sarcolemma are then
667:– recent animal study research has shown that constant flow of ions such as calcium and sodium through channels in the soma and dendrites influence the synaptic input. An alternate way to think of this is that the post-synaptic neuron is being primed before receiving an impulse.
606:
Fast fatigue-resistant motor units stimulate moderate-sized muscles groups that do not react as fast as the FF motor units, but can be sustained much longer (as implied by the name) and provide more force than S motor units. These use both oxidative and glycolytic means to gain
661:– this relates to the soma of the motor neuron. This restricts larger neurons to receive a larger excitatory signal in order to stimulate the muscle fibers it innervates. By reducing unnecessary muscle fiber recruitment, the body is able to optimize energy consumption.
1846:
Azevedo, Anthony; Lesser, Ellen; Mark, Brandon; Phelps, Jasper; Elabbady, Leila; Kuroda, Sumiya; Sustar, Anne; Moussa, Anthony; Kandelwal, Avinash; Dallmann, Chris J.; Agrawal, Sweta; Lee, Su-Yee J.; Pratt, Brandon; Cook, Andrew; Skutt-Kakaria, Kyobi (2022-12-15).
677:– A trend has been identified that shows slow motor neurons to have more intense AHPs for a longer duration. One way to remember this is that slow muscle fibers can contract for longer, so it makes sense that their corresponding motor neurons fire at a slower rate.
966:, however, the response of a muscle fiber to a neurotransmitter can only be excitatory, in other words, contractile. Muscle relaxation and inhibition of muscle contraction in vertebrates is obtained only by inhibition of the motor neuron itself. This is how
289:
transcription factors. There are 13 Hox transcription factors and along with the signals, determine whether a motor neuron will be more rostral or caudal in character. In the spinal column, Hox 4-11 sort motor neurons to one of the five motor columns.
456:
to their effectors. In the spinal cord these descending tracts carry impulses from different regions. These tracts also serve as the place of origin for lower motor neurons. There are seven major descending motor tracts to be found in the spinal cord:
625:
detect the degree of stretch and send a signal to the CNS. The CNS activates alpha motor neurons in the spinal cord, which cause extrafusal muscle fibers to contract and thereby resist further stretching. This process is also called the
1347:
Edgar R, Mazor Y, Rinon A, Blumenthal J, Golan Y, Buzhor E, Livnat I, Ben-Ari S, Lieder I, Shitrit A, Gilboa Y, Ben-Yehudah A, Edri O, Shraga N, Bogoch Y, Leshansky L, Aharoni S, West MD, Warshawsky D, Shtrichman R (2013).
1471:
Fitzpatrick, D. (2001) The
Primary Motor Cortex: Upper Motor Neurons That Initiate Complex Voluntary Movements. In D. Purves, G.J. Augustine, D. Fitzpatrick, et al. (Ed.), Neuroscience. Retrieved from
645:, with collaterals to extrafusal fibres. There are two types of beta motor neurons: Slow Contracting- These innervate extrafusal fibers. Fast Contracting- These innervate intrafusal fibers.
652:
reflex. There are two types of gamma motor neurons: Dynamic- These focus on Bag1 fibers and enhance dynamic sensitivity. Static- These focus on Bag2 fibers and enhance stretch sensitivity.
429:
project from the primary cortex directly onto motor neurons in the ventral horn of the spinal cord. Their axons synapse on the spinal motor neurons of multiple muscles as well as on spinal
437:
including the relatively independent control of individual fingers. Corticomotorneurons have so far only been found in the primary motor cortex and not in secondary motor areas.
1653:
Fitzpatrick, D. (2001) Lower Motor Neuron
Circuits and Motor Control: Overview. In D. Purves, G.J. Augustine, D. Fitzpatrick, et al. (Ed.), Neuroscience. Retrieved from
1534:
962:, depending on the neurotransmitter released and the type of receptor it binds, the response in the muscle fiber could be either excitatory or inhibitory. For
955:
stimulated to elicit calcium ion release from the sarcoplasmic reticulum. It is this chemical release that causes the target muscle fiber to contract.
1691:
1966:
591:. A single motor neuron may synapse with 150 muscle fibers on average. The motor neuron and all of the muscle fibers to which it connects is a
1721:
1287:
1262:
1218:
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1156:
1116:
919:. As a result, if an action potential arrives before a twitch has completed, the twitches can superimpose on one another, either through
1795:
Manuel, Marin; Zytnicki, Daniel (2011). "Alpha, Beta, and Gamma
Motoneurons: Functional Diversity in the Motor System's Final Pathway".
266:, a gene that causes cell cycle exiting as well as promoting further transcription factors associated with motor neuron development.
1935:
1912:
1510:
39:
2590:
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2130:
1026:. For any given motor neuron, determining the relative contribution of different input sources is difficult, but advances in
143:(fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly
1640:
Tortora, G. J., Derrickson, B. (2011). The Spinal Cord and Spinal Nerves. In B. Roesch, L. Elfers, K. Trost, et al. (Ed.),
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of motor neurons begin to appear in the fourth week of development from the ventral region of the ventral-dorsal axis (the
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1659:
1477:
1023:
1474:"The Primary Motor Cortex: Upper Motor Neurons That Initiate Complex Voluntary Movements - Neuroscience - NCBI Bookshelf"
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461:
1501:
Mack, Sarah; Kandel, Eric R.; Jessell, Thomas M.; Schwartz, James H.; Siegelbaum, Steven A.; Hudspeth, A. J. (2013).
692:, which are involved in facial expression, mastication, phonation, and swallowing. Associated cranial nerves are the
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282:
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in the spinal cord and occasionally directly onto lower motor neurons. The axons from the lower motor neurons are
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846:
569:
235:
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from synaptic vesicles bound to the plasma membrane of the axon terminals. The acetylcholine molecules bind to
834:
274:
210:. Individual twitches can become indistinguishable, and tension rises smoothly eventually reaching a plateau.
927:. In summation, the muscle is stimulated repetitively such that additional action potentials coming from the
880:, located in the CNS, synapses onto a ganglionic neuron, located in the PNS, which synapses onto the muscle.
2224:
1952:
1606:
Isa, T (April 2007). "Direct and indirect cortico-motoneuronal pathways and control of hand/arm movements".
1031:
951:
638:
617:, the continuous force generated by noncontracting muscle to oppose stretching. When a muscle is stretched,
580:
891:. Parasympathetic ganglionic neurons are also cholinergic, whereas most sympathetic ganglionic neurons are
433:. They are unique to primates and it has been suggested that their function is the adaptive control of the
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2219:
1983:
1683:
940:
928:
565:
529:
278:
199:
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Tortora, G. J., Derrickson, B. (2011). Muscular Tissue. In B. Roesch, L. Elfers, K. Trost, et al. (Ed.),
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2550:
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1350:"LifeMap Discovery™: The Embryonic Development, Stem Cells, and Regenerative Medicine Research Portal"
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Schacter D.L., Gilbert D.T., and Wegner D.M. (2011) Psychology second edition. New York, NY: Worth
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Philippidou, Polyxeni; Walsh, Carolyn; Aubin, Josée; Jeannotte, Lucie; Dasen, Jeremy S. (2012).
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Brachial and lumbar region (both regions are further divided into medial and lateral domains)
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In addition to voluntary skeletal muscle contraction, alpha motor neurons also contribute to
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2008:
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583:, which are the main force-generating component of a muscle. Their cell bodies are in the
52:
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motor neurons. In the fly, motor neurons controlling the legs and wings are found in the
849:(PNS), which themselves directly innervate visceral muscles (and also some gland cells).
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Purves D, Augustine GJ, Fitzpatrick D, et al., editors: Neuroscience. 2nd edition, 2001
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Motor neurons receive synaptic input from premotor neurons. Premotor neurons can be 1)
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814:
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642:
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418:
259:
943:. Upon adequate stimulation, the motor neuron releases a flood of acetylcholine (Ach)
509:
According to their targets, motor neurons are classified into three broad categories:
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223:
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2003:
1417:"Sustained Hox5 Gene Activity is Required for Respiratory Motor Neuron Development"
1282:(11th ed.). Philadelphia: Lippincott William & Wilkins. pp. 299–301.
1027:
1019:
948:
791:
449:
402:
128:
1849:"Tools for comprehensive reconstruction and analysis of Drosophila motor circuits"
230:
cells are specified to either the rostral-caudal axis or ventral-dorsal axis. The
1924:
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2347:
2279:
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2028:
1998:
1234:
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work by acting on the motor neurons that innervate muscles (by decreasing their
963:
884:
787:
614:
445:
430:
227:
168:
160:
136:
77:
1761:
1656:"Lower Motor Neuron Circuits and Motor Control - Neuroscience - NCBI Bookshelf"
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263:
44:
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indistinguishable, and tension rises smoothly eventually reaching a plateau.
2755:
2289:
2140:
2113:
2105:
1051:
1007:
414:
262:(Shh). The OLIG2 gene being the most important due to its role in promoting
132:
124:
56:
17:
1824:
1627:
1584:
1458:
1401:
1333:
238:). This homeodomain is known as the motor neural progenitor domain (pMN).
2419:
2404:
2399:
2123:
2118:
2045:
2040:
1555:
Lemon, Roger N. (April 4, 2008). "Descending
Pathways in Motor Control".
822:
286:
2682:
2643:
1324:
1307:
1306:
Davis-Dusenbery, BN; Williams, LA; Klim, JR; Eggan, K (February 2014).
936:
935:
The interface between a motor neuron and muscle fiber is a specialized
908:
830:
826:
818:
187:
226:, and motor function continues to develop well into childhood. In the
2342:
2297:
2062:
995:
255:
251:
144:
120:
1432:
1176:(3rd ed.). Oxford: Oxford University Press. pp. 151–153.
1253:(14th ed.). New Jersey: John Wiley & Sons, Inc. pp.
1147:(14th ed.). New Jersey: John Wiley & Sons, Inc. pp.
1117:"Afferent vs. Efferent: AP® Psych Crash Course Review | Albert.io"
1071:
533:
434:
384:
376:
247:
148:
1944:
868:, which synapses onto the muscle. Comparatively, the command of
2535:
2381:
978:
neuromuscular junctions, rather than on the muscles themselves.
243:
231:
140:
1948:
421:. The axons of these cells descend from the cortex to form the
1743:(pp. 305-307, 311). New Jersey: John Wiley & Sons, Inc.
51:
showing motor neurons with their characteristic coarse
1644:(pp. 443-468). New Jersey: John Wiley & Sons, Inc.
202:
and twitches can become superimposed as a result of
2701:
2642:
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2380:
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2157:
2104:
2061:
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1991:
1982:
1930:(2nd ed.). Menlo Park, CA: Benjamin/Cummings.
710:
269:Further specification of motor neurons occurs when
171:to the effectors. Types of lower motor neurons are
95:
87:
69:
64:
32:
1923:
1204:
1202:
1172:Pocock, Gillian; Richards, Christopher D. (2006).
540:(such as the muscles of the limbs, abdominal, and
587:of the spinal cord and they are sometimes called
1907:(4th ed.). Pacific Grove, CA: Brooks-Cole.
1762:"The Motor Unit - Neuroscience - NCBI Bookshelf"
994:that convey information from the periphery and
595:. Motor units are split up into 3 categories:
389:Location of lower motor neurons in spinal cord
159:. Axons from upper motor neurons synapse onto
1960:
1235:https://www.ncbi.nlm.nih.gov/books/NBK554616/
1174:Human physiology : the basis of medicine
990:that have cell bodies in the spinal cord, 2)
895:, that is, they release the neurotransmitter
887:, that is, they release the neurotransmitter
564:to indicate the flow of information from the
8:
1505:. Kandel, Eric R. (5th ed.). New York.
1247:Tortora, Gerard; Derrickson, Bryan (2011).
1141:Tortora, Gerard; Derrickson, Bryan (2014).
548:. The three types of these neurons are the
2639:
2359:
2352:
2163:
2058:
1988:
1967:
1953:
1945:
1533:: CS1 maint: location missing publisher (
1213:. Toronto: Nelson Education. p. 946.
655:Regulatory factors of lower motor neurons
38:
1448:
1391:
1373:
1323:
1211:Biology - Exploring the Diversity of Life
907:A single motor neuron may innervate many
809:These motor neurons indirectly innervate
186:A single motor neuron may innervate many
151:. There are two types of motor neuron –
1714:Human Physiology: An Integrated Approach
860:involving only one motor neuron, either
784:
599:oxygen. They are also called red fibers.
292:
222:Motor neurons begin to develop early in
1905:Human Physiology: From Cells to Systems
1108:
528:Somatic motor neurons originate in the
1881:
1870:
1569:10.1146/annurev.neuro.31.060407.125547
1550:
1548:
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1144:Principles of Anatomy & Physiology
29:
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852:In consequence, the motor command of
7:
1741:Principles of Anatomy and Physiology
1642:Principles of Anatomy and Physiology
1301:
1299:
911:and a muscle fibre can undergo many
190:and a muscle fibre can undergo many
27:Nerve cell sending impulse to muscle
1922:Marieb, E. N.; Mallatt, J. (1997).
1797:Journal of Integrative Neuroscience
1308:"How to make spinal motor neurons"
285:, are integrated into the various
25:
1712:Silverthorn, Dee Unglaub (2010).
1002:that convey information from the
996:synapse directly onto motoneurons
883:All vertebrate motor neurons are
1250:Principles of Anatomy Physiology
2131:Oligodendrocyte progenitor cell
1768:from the original on 2018-06-05
1694:from the original on 2017-11-05
1662:from the original on 2018-06-05
1480:from the original on 2018-06-05
982:Synaptic input to motor neurons
915:in the time taken for a single
712:
665:Persistent Inward Current (PIC)
198:. Innervation takes place at a
194:in the time taken for a single
805:General visceral motor neurons
797:Motor neuron neurotransmitters
684:Special visceral motor neurons
519:General visceral motor neurons
516:Special visceral motor neurons
294:Motor columns of spinal cord
1:
1557:Annual Review of Neuroscience
878:general visceral motor neuron
409:. The cells that make up the
1503:Principles of neural science
1375:10.1371/journal.pone.0066629
1280:Langman's medical embryology
492:Anterior corticospinal tract
472:Lateral reticulospinal tract
338:Preganglionic motor column
167:that carry signals from the
2241:Postganglionic nerve fibers
876:involving two neurons: the
506:divided in sub-categories.
482:Medial reticulospinal tract
462:Lateral corticospinal tract
2807:
2236:Preganglionic nerve fibers
1620:10.1152/physiol.00045.2006
1030:have made it possible for
99:Excitatory projection (to
2746:Olfactory receptor neuron
2410:Neurofibril/neurofilament
1857:10.1101/2022.12.15.520299
1809:10.1142/S0219635211002786
856:and branchial muscles is
847:peripheral nervous system
544:), which are involved in
258:, which are regulated by
37:
1716:. Pearson. p. 398.
835:autonomic nervous system
829:onto neurons located in
688:These are also known as
639:intrafusal muscle fibers
603:are called white fibers.
581:extrafusal muscle fibers
448:are bundles of axons as
305:Location in spinal cord
275:fibroblast growth factor
1209:Russell, Peter (2013).
903:Neuromuscular junctions
690:branchial motor neurons
327:Hypaxial motor column
55:("tigroid" cytoplasm).
2693:Neuromuscular junction
2556:III or Aδ or fast pain
1880:Cite journal requires
1010:. The synapses can be
941:neuromuscular junction
929:somatic nervous system
566:central nervous system
558:gamma efferent neurons
550:alpha efferent neurons
530:central nervous system
390:
382:
373:Anatomy and physiology
360:Phrenic motor column
344:Sympathetic ganglion
319:Present entire length
200:neuromuscular junction
1903:Sherwood, L. (2001).
1851:: 2022.12.15.520299.
1057:Central chromatolysis
821:( the muscles of the
554:beta efferent neurons
524:Somatic motor neurons
513:Somatic motor neurons
477:Vestibulospinal tract
388:
380:
355:Muscles of the limbs
349:Lateral motor column
240:Transcription factors
224:embryonic development
165:efferent nerve fibers
2711:Meissner's corpuscle
2676:Postsynaptic density
2573:Efferent nerve fiber
2561:IV or C or slow pain
2503:Afferent nerve fiber
2329:Satellite glial cell
1092:Efferent nerve fiber
1087:Afferent nerve fiber
1067:Motor neuron disease
1038:, homologous to the
972:electrophysiological
411:primary motor cortex
316:Median motor column
82:cranial nerve nuclei
2716:Merkel nerve ending
1421:Nature Neuroscience
1366:2013PLoSO...866629E
1278:Sadler, T. (2010).
988:spinal interneurons
925:tetanic contraction
649:Gamma motor neurons
577:Alpha motor neurons
542:intercostal muscles
503:Lower motor neurons
498:Lower motor neurons
427:Corticomotorneurons
423:corticospinal tract
399:Upper motor neurons
394:Upper motor neurons
295:
208:tetanic contraction
181:gamma motor neurons
173:alpha motor neurons
157:lower motor neurons
153:upper motor neurons
49:hypoglossal nucleus
2751:Photoreceptor cell
2721:Pacinian corpuscle
2652:Electrical synapse
2606:Lower motor neuron
2601:Upper motor neuron
2322:Internodal segment
2262:Connective tissues
2232:Autonomic ganglion
1325:10.1242/dev.097410
1036:ventral nerve cord
1000:descending neurons
845:), located in the
786:*Except fibers to
673:Hyper-polarization
635:Beta motor neurons
589:ventral horn cells
560:. They are called
417:, which are giant
391:
383:
381:Spinal cord tracts
333:Body wall muscles
293:
177:beta motor neurons
127:is located in the
2773:
2772:
2769:
2768:
2736:Free nerve ending
2703:Sensory receptors
2631:
2630:
2546:Ib or Golgi or Aα
2454:
2453:
2337:
2336:
2214:Ramus communicans
2153:
2152:
2149:
2148:
2019:Commissural fiber
2014:Association fiber
2009:Projection fibers
1723:978-0-321-55980-7
1427:(12): 1636–1644.
1289:978-0-7817-9069-7
1264:978-1-118-34500-9
1220:978-0-17-665133-6
1183:978-0-19-856878-0
1158:978-1-118-34500-9
1062:Motor dysfunction
945:neurotransmitters
913:action potentials
802:
801:
720:Neurotransmitter
487:Tectospinal tract
467:Rubrospinal tract
454:action potentials
401:originate in the
370:
369:
192:action potentials
105:
104:
100:
91:Projection neuron
57:H&E-LFB stain
16:(Redirected from
2798:
2786:Efferent neurons
2666:Synaptic vesicle
2661:Chemical synapse
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1377:
1344:
1338:
1337:
1327:
1303:
1294:
1293:
1275:
1269:
1268:
1244:
1238:
1231:
1225:
1224:
1206:
1197:
1194:
1188:
1187:
1169:
1163:
1162:
1138:
1132:
1131:
1129:
1128:
1121:Albert Resources
1113:
974:activity) or on
968:muscle relaxants
870:visceral muscles
794:
749:Parasympathetic
738:Parasympathetic
711:
538:skeletal muscles
532:, project their
407:precentral gyrus
363:Cervical region
341:Thoracic region
330:Thoracic region
296:
42:
30:
21:
2806:
2805:
2801:
2800:
2799:
2797:
2796:
2795:
2776:
2775:
2774:
2765:
2697:
2627:
2576:
2567:
2551:II or Aβ and Aγ
2506:
2497:
2450:
2440:Apical dendrite
2435:Dendritic spine
2414:
2376:
2346:
2333:
2317:Node of Ranvier
2312:Myelin incisure
2284:
2256:
2145:
2136:Oligodendrocyte
2119:Ependymal cells
2100:
2050:
1978:
1973:
1938:
1921:
1915:
1902:
1899:
1894:
1893:
1879:
1869:
1845:
1844:
1840:
1794:
1793:
1780:
1771:
1769:
1760:
1758:
1747:
1738:
1731:
1724:
1711:
1710:
1706:
1697:
1695:
1682:
1681:
1674:
1665:
1663:
1654:
1652:
1648:
1639:
1635:
1605:
1604:
1600:
1554:
1553:
1542:
1525:
1513:
1500:
1499:
1492:
1483:
1481:
1472:
1470:
1466:
1433:10.1038/nn.3242
1414:
1413:
1409:
1346:
1345:
1341:
1305:
1304:
1297:
1290:
1277:
1276:
1272:
1265:
1246:
1245:
1241:
1232:
1228:
1221:
1208:
1207:
1200:
1195:
1191:
1184:
1171:
1170:
1166:
1159:
1140:
1139:
1135:
1126:
1124:
1115:
1114:
1110:
1105:
1048:
1024:neuromodulatory
992:sensory neurons
984:
905:
843:parasympathetic
807:
795:
785:
686:
643:muscle spindles
619:sensory neurons
526:
500:
443:
419:pyramidal cells
405:located in the
396:
375:
264:Ngn2 expression
220:
117:efferent neuron
101:
60:
53:Nissl substance
28:
23:
22:
15:
12:
11:
5:
2804:
2802:
2794:
2793:
2788:
2778:
2777:
2771:
2770:
2767:
2766:
2764:
2763:
2761:Taste receptor
2758:
2753:
2748:
2743:
2738:
2733:
2731:Muscle spindle
2728:
2726:Ruffini ending
2723:
2718:
2713:
2707:
2705:
2699:
2698:
2696:
2695:
2690:
2688:Ribbon synapse
2685:
2680:
2679:
2678:
2673:
2668:
2658:
2648:
2646:
2637:
2633:
2632:
2629:
2628:
2626:
2625:
2624:
2623:
2618:
2613:
2603:
2598:
2593:
2588:
2582:
2580:
2569:
2568:
2566:
2565:
2564:
2563:
2558:
2553:
2548:
2543:
2533:
2528:
2523:
2518:
2512:
2510:
2508:Sensory neuron
2499:
2498:
2496:
2495:
2494:
2493:
2483:
2478:
2476:Pseudounipolar
2473:
2468:
2462:
2460:
2456:
2455:
2452:
2451:
2449:
2448:
2447:
2446:
2444:Basal dendrite
2437:
2432:
2424:
2422:
2416:
2415:
2413:
2412:
2407:
2402:
2397:
2395:Axon terminals
2392:
2386:
2384:
2378:
2377:
2375:
2374:
2368:
2366:
2357:
2350:
2339:
2338:
2335:
2334:
2332:
2331:
2326:
2325:
2324:
2319:
2314:
2309:
2294:
2292:
2286:
2285:
2283:
2282:
2277:
2272:
2266:
2264:
2258:
2257:
2255:
2254:
2249:
2247:Nerve fascicle
2244:
2238:
2229:
2228:
2227:
2222:
2210:
2209:
2208:
2203:
2193:
2192:
2191:
2186:
2181:
2170:
2168:
2161:
2155:
2154:
2151:
2150:
2147:
2146:
2144:
2143:
2138:
2133:
2128:
2127:
2126:
2116:
2110:
2108:
2102:
2101:
2099:
2098:
2093:
2088:
2083:
2078:
2073:
2067:
2065:
2056:
2052:
2051:
2049:
2048:
2043:
2038:
2037:
2036:
2031:
2026:
2021:
2016:
2011:
2001:
1995:
1993:
1986:
1980:
1979:
1976:Nervous tissue
1974:
1972:
1971:
1964:
1957:
1949:
1943:
1942:
1936:
1919:
1913:
1898:
1895:
1892:
1891:
1882:|journal=
1838:
1803:(3): 243–276.
1778:
1745:
1729:
1722:
1704:
1684:"CHAPTER NINE"
1672:
1646:
1633:
1614:(2): 145–152.
1598:
1563:(1): 195–218.
1540:
1511:
1490:
1464:
1407:
1339:
1318:(3): 491–501.
1295:
1288:
1270:
1263:
1239:
1226:
1219:
1198:
1189:
1182:
1164:
1157:
1133:
1107:
1106:
1104:
1101:
1100:
1099:
1097:Sensory neuron
1094:
1089:
1084:
1079:
1074:
1069:
1064:
1059:
1054:
1047:
1044:
983:
980:
904:
901:
899:. (see Table)
815:smooth muscles
811:cardiac muscle
806:
803:
800:
799:
782:
781:
778:Norepinephrine
775:
772:
768:
767:
766:Acetylcholine
764:
763:Preganglionic
761:
757:
756:
755:Acetylcholine
753:
750:
746:
745:
744:Acetylcholine
742:
741:Preganglionic
739:
735:
734:
729:
726:
722:
721:
718:
715:
685:
682:
681:
680:
679:
678:
668:
662:
659:Size Principle
653:
646:
628:stretch reflex
623:muscle spindle
611:
610:
609:
608:
604:
600:
525:
522:
521:
520:
517:
514:
499:
496:
495:
494:
489:
484:
479:
474:
469:
464:
442:
439:
395:
392:
374:
371:
368:
367:
364:
361:
357:
356:
353:
350:
346:
345:
342:
339:
335:
334:
331:
328:
324:
323:
322:Axial muscles
320:
317:
313:
312:
307:
302:
260:sonic hedgehog
219:
216:
103:
102:
97:
93:
92:
89:
85:
84:
71:
67:
66:
62:
61:
43:
35:
34:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2803:
2792:
2789:
2787:
2784:
2783:
2781:
2762:
2759:
2757:
2754:
2752:
2749:
2747:
2744:
2742:
2739:
2737:
2734:
2732:
2729:
2727:
2724:
2722:
2719:
2717:
2714:
2712:
2709:
2708:
2706:
2704:
2700:
2694:
2691:
2689:
2686:
2684:
2681:
2677:
2674:
2672:
2669:
2667:
2664:
2663:
2662:
2659:
2657:
2653:
2650:
2649:
2647:
2645:
2641:
2638:
2634:
2622:
2621:γ motorneuron
2619:
2617:
2616:β motorneuron
2614:
2612:
2611:α motorneuron
2609:
2608:
2607:
2604:
2602:
2599:
2597:
2594:
2592:
2589:
2587:
2584:
2583:
2581:
2579:
2574:
2570:
2562:
2559:
2557:
2554:
2552:
2549:
2547:
2544:
2542:
2539:
2538:
2537:
2534:
2532:
2529:
2527:
2524:
2522:
2519:
2517:
2514:
2513:
2511:
2509:
2504:
2500:
2492:
2489:
2488:
2487:
2484:
2482:
2479:
2477:
2474:
2472:
2469:
2467:
2464:
2463:
2461:
2457:
2445:
2441:
2438:
2436:
2433:
2431:
2428:
2427:
2426:
2425:
2423:
2421:
2417:
2411:
2408:
2406:
2403:
2401:
2398:
2396:
2393:
2391:
2388:
2387:
2385:
2383:
2379:
2373:
2370:
2369:
2367:
2365:
2361:
2358:
2354:
2351:
2349:
2344:
2340:
2330:
2327:
2323:
2320:
2318:
2315:
2313:
2310:
2308:
2305:
2304:
2303:
2299:
2296:
2295:
2293:
2291:
2287:
2281:
2278:
2276:
2273:
2271:
2268:
2267:
2265:
2263:
2259:
2253:
2250:
2248:
2245:
2242:
2239:
2237:
2233:
2230:
2226:
2223:
2221:
2218:
2217:
2216:
2215:
2211:
2207:
2204:
2202:
2199:
2198:
2197:
2194:
2190:
2187:
2185:
2182:
2180:
2177:
2176:
2175:
2172:
2171:
2169:
2165:
2162:
2160:
2156:
2142:
2139:
2137:
2134:
2132:
2129:
2125:
2122:
2121:
2120:
2117:
2115:
2112:
2111:
2109:
2107:
2103:
2097:
2094:
2092:
2089:
2087:
2084:
2082:
2079:
2077:
2074:
2072:
2069:
2068:
2066:
2064:
2060:
2057:
2053:
2047:
2044:
2042:
2039:
2035:
2032:
2030:
2027:
2025:
2022:
2020:
2017:
2015:
2012:
2010:
2007:
2006:
2005:
2002:
2000:
1997:
1996:
1994:
1990:
1987:
1985:
1981:
1977:
1970:
1965:
1963:
1958:
1956:
1951:
1950:
1947:
1939:
1937:0-8053-4068-8
1933:
1928:
1927:
1926:Human Anatomy
1920:
1916:
1914:0-534-37254-6
1910:
1906:
1901:
1900:
1896:
1887:
1874:
1866:
1862:
1858:
1854:
1850:
1842:
1839:
1834:
1830:
1826:
1822:
1818:
1814:
1810:
1806:
1802:
1798:
1791:
1789:
1787:
1785:
1783:
1779:
1767:
1763:
1756:
1754:
1752:
1750:
1746:
1742:
1736:
1734:
1730:
1725:
1719:
1715:
1708:
1705:
1693:
1689:
1685:
1679:
1677:
1673:
1661:
1657:
1650:
1647:
1643:
1637:
1634:
1629:
1625:
1621:
1617:
1613:
1609:
1602:
1599:
1594:
1590:
1586:
1582:
1578:
1574:
1570:
1566:
1562:
1558:
1551:
1549:
1547:
1545:
1541:
1536:
1530:
1522:
1518:
1514:
1512:9780071390118
1508:
1504:
1497:
1495:
1491:
1479:
1475:
1468:
1465:
1460:
1456:
1451:
1446:
1442:
1438:
1434:
1430:
1426:
1422:
1418:
1411:
1408:
1403:
1399:
1394:
1389:
1385:
1381:
1376:
1371:
1367:
1363:
1360:(7): e66629.
1359:
1355:
1351:
1343:
1340:
1335:
1331:
1326:
1321:
1317:
1313:
1309:
1302:
1300:
1296:
1291:
1285:
1281:
1274:
1271:
1266:
1260:
1256:
1252:
1251:
1243:
1240:
1236:
1230:
1227:
1222:
1216:
1212:
1205:
1203:
1199:
1193:
1190:
1185:
1179:
1175:
1168:
1165:
1160:
1154:
1150:
1149:406, 502, 541
1146:
1145:
1137:
1134:
1122:
1118:
1112:
1109:
1102:
1098:
1095:
1093:
1090:
1088:
1085:
1083:
1080:
1078:
1077:Sensory nerve
1075:
1073:
1070:
1068:
1065:
1063:
1060:
1058:
1055:
1053:
1050:
1049:
1045:
1043:
1041:
1037:
1033:
1029:
1025:
1021:
1017:
1013:
1009:
1005:
1001:
997:
993:
989:
981:
979:
977:
973:
969:
965:
961:
960:invertebrates
956:
953:
950:
946:
942:
938:
933:
930:
926:
922:
918:
917:muscle twitch
914:
910:
909:muscle fibres
902:
900:
898:
897:noradrenaline
894:
893:noradrenergic
890:
889:acetylcholine
886:
881:
879:
875:
871:
867:
863:
859:
855:
850:
848:
844:
840:
836:
832:
828:
824:
820:
816:
812:
804:
798:
793:
792:blood vessels
789:
783:
779:
776:
773:
770:
769:
765:
762:
759:
758:
754:
751:
748:
747:
743:
740:
737:
736:
733:
732:Acetylcholine
730:
727:
724:
723:
719:
716:
714:Branch of NS
713:
709:
707:
703:
699:
695:
691:
683:
676:
674:
669:
666:
663:
660:
657:
656:
654:
650:
647:
644:
640:
636:
633:
632:
631:
629:
624:
620:
616:
605:
601:
597:
596:
594:
590:
586:
582:
578:
575:
574:
573:
571:
568:(CNS) to the
567:
563:
559:
555:
551:
547:
543:
539:
535:
531:
523:
518:
515:
512:
511:
510:
507:
504:
497:
493:
490:
488:
485:
483:
480:
478:
475:
473:
470:
468:
465:
463:
460:
459:
458:
455:
452:, that carry
451:
447:
440:
438:
436:
432:
428:
424:
420:
416:
412:
408:
404:
400:
393:
387:
379:
372:
365:
362:
359:
358:
354:
351:
348:
347:
343:
340:
337:
336:
332:
329:
326:
325:
321:
318:
315:
314:
311:
308:
306:
303:
301:
298:
297:
291:
288:
284:
280:
276:
272:
271:retinoic acid
267:
265:
261:
257:
253:
249:
245:
242:here include
241:
237:
233:
229:
225:
217:
215:
211:
209:
205:
201:
197:
196:muscle twitch
193:
189:
188:muscle fibres
184:
182:
178:
174:
170:
166:
162:
158:
154:
150:
146:
142:
138:
134:
130:
126:
122:
118:
114:
110:
98:
94:
90:
86:
83:
79:
75:
72:
68:
63:
58:
54:
50:
46:
41:
36:
33:Motor neurons
31:
19:
2791:Motor system
2656:Gap junction
2578:Motor neuron
2577:
2372:Axon hillock
2348:nerve fibers
2302:Schwann cell
2212:
2195:
2173:
2091:Medium spiny
2004:White matter
1992:Tissue Types
1925:
1904:
1873:cite journal
1841:
1800:
1796:
1770:. Retrieved
1740:
1713:
1707:
1696:. Retrieved
1687:
1664:. Retrieved
1649:
1641:
1636:
1611:
1607:
1601:
1560:
1556:
1502:
1482:. Retrieved
1467:
1424:
1420:
1410:
1357:
1353:
1342:
1315:
1311:
1279:
1273:
1249:
1242:
1229:
1210:
1192:
1173:
1167:
1143:
1136:
1125:. Retrieved
1123:. 2019-12-02
1120:
1111:
1028:connectomics
985:
957:
949:postsynaptic
934:
906:
882:
877:
873:
865:
861:
858:monosynaptic
857:
851:
808:
796:
790:and certain
788:sweat glands
771:Sympathetic
760:Sympathetic
689:
687:
670:
664:
658:
612:
588:
585:ventral horn
557:
553:
549:
527:
508:
501:
450:white matter
446:Nerve tracts
444:
441:Nerve tracts
431:interneurons
403:motor cortex
397:
309:
304:
300:Motor column
299:
268:
221:
212:
185:
161:interneurons
139:, and whose
129:motor cortex
116:
112:
109:motor neuron
108:
106:
74:Ventral horn
18:Motor nerves
2671:Active zone
2636:Termination
2486:Interneuron
2390:Telodendron
2298:Myelination
2280:Endoneurium
2275:Perineurium
2096:Interneuron
2086:Von Economo
2034:Decussation
2029:Nerve tract
1999:Grey matter
1688:www.unc.edu
1312:Development
1082:Motor nerve
1040:spinal cord
976:cholinergic
964:vertebrates
939:called the
885:cholinergic
839:sympathetic
774:Ganglionic
752:Ganglionic
706:hypoglossal
621:within the
615:muscle tone
236:basal plate
228:neural tube
218:Development
169:spinal cord
137:spinal cord
78:spinal cord
2780:Categories
2741:Nociceptor
2481:Multipolar
2430:Nissl body
2307:Neurilemma
2270:Epineurium
2055:Cell Types
1772:2017-09-05
1698:2017-12-08
1666:2017-11-30
1608:Physiology
1484:2017-11-30
1127:2021-04-25
1103:References
1020:electrical
1016:inhibitory
1012:excitatory
874:disynaptic
694:oculomotor
637:innervate
593:motor unit
579:innervate
546:locomotion
415:Betz cells
366:Diaphragm
113:motoneuron
45:Micrograph
2756:Hair cell
2290:Neuroglia
2252:Funiculus
2141:Microglia
2114:Astrocyte
2071:Pyramidal
2024:Lemniscus
1865:254736092
1817:0219-6352
1577:0147-006X
1529:cite book
1521:795553723
1441:1097-6256
1384:1932-6203
1255:1090–1099
1052:Betz cell
1032:fruit fly
1008:brainstem
952:receptors
921:summation
866:branchial
717:Position
702:trochlear
570:periphery
204:summation
133:brainstem
125:cell body
2541:Ia or Aα
2471:Unipolar
2420:Dendrite
2405:Axolemma
2400:Axoplasm
2184:Ganglion
2124:Tanycyte
2076:Purkinje
2063:Neuronal
2046:Meninges
2041:Neuropil
1833:21582283
1825:21960303
1766:Archived
1692:Archived
1660:Archived
1628:17420305
1593:16139768
1585:18558853
1478:Archived
1459:23103965
1402:23874394
1354:PLOS ONE
1334:24449832
1046:See also
854:skeletal
825:): they
823:arteries
725:Somatic
708:nerves.
698:abducens
562:efferent
96:Function
70:Location
2683:Autapse
2644:Synapse
2491:Renshaw
2466:Bipolar
2343:Neurons
2196:Ventral
2167:General
2081:Granule
1897:Sources
1450:3676175
1393:3714290
1362:Bibcode
937:synapse
862:somatic
833:of the
831:ganglia
827:synapse
819:viscera
817:of the
607:energy.
256:Nkx-6.2
252:Nkx-6.1
145:muscles
135:or the
119:) is a
80:, some
76:of the
65:Details
47:of the
2536:fibers
2174:Dorsal
1934:
1911:
1863:
1831:
1823:
1815:
1720:
1626:
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704:, and
671:After
556:, and
310:Target
281:, and
254:, and
179:, and
149:glands
123:whose
121:neuron
2459:Types
2356:Parts
2225:White
2206:Ramus
2189:Ramus
2106:Glial
1861:S2CID
1829:S2CID
1589:S2CID
1072:Nerve
1022:, or
1004:brain
998:, 3)
923:or a
675:(AHP)
534:axons
435:hands
248:OLIG2
232:axons
206:or a
88:Shape
2382:Axon
2364:Soma
2220:Gray
2201:Root
2179:Root
1932:ISBN
1909:ISBN
1886:help
1821:PMID
1813:ISSN
1718:ISBN
1624:PMID
1581:PMID
1573:ISSN
1535:link
1517:OCLC
1507:ISBN
1455:PMID
1437:ISSN
1398:PMID
1380:ISSN
1330:PMID
1284:ISBN
1259:ISBN
1215:ISBN
1178:ISBN
1153:ISBN
1006:and
841:and
813:and
728:n/a
413:are
283:TGFb
279:Wnts
244:Pax6
155:and
147:and
141:axon
111:(or
2596:SVE
2591:GVE
2586:GSE
2531:SVA
2526:SSA
2521:GVA
2516:GSA
2159:PNS
1984:CNS
1853:doi
1805:doi
1616:doi
1565:doi
1445:PMC
1429:doi
1388:PMC
1370:doi
1320:doi
1316:141
958:In
872:is
864:or
641:of
536:to
287:Hox
115:or
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