Solitary nucleus

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Solitary nucleus

?

The?cranial nerve nuclei?schematically represented; dorsal view. Motor nuclei in red; sensory in blue.

?

Transverse section of?medulla oblongata?of human?embryo.

Details

Identifiers

Latin

Nucleus tractus solitarii medullae oblongatae.

MeSH

D017552

NeuroNames

742

NeuroLex?ID

birnlex_1429

TA98

A14.1.04.230

TA2

6008

FMA

72242

Anatomical terms of neuroanatomy

[edit on Wikidata]

In the human brainstem, the?solitary nucleus?(SN)?(nucleus of the solitary tract,?nucleus solitarius,?nucleus tractus solitarii) is a series of purely sensory?nuclei(clusters of nerve cell bodies) forming a vertical column of?grey matter?embedded in the?medulla oblongata. Through the center of the SN runs the?solitary tract, a white bundle of nerve fibers, including fibers from the?facial,?glossopharyngeal?and?vagus nerves, that?innervate?the SN. The SN projects to, among other regions, the?reticular formation,?parasympathetic preganglionic neurons,?hypothalamus?and?thalamus, forming circuits that contribute to autonomic regulation. Cells along the length of the SN are arranged roughly in accordance with function; for instance,?cells involved in taste are located in the rostral part, while those receiving information from cardio-respiratory and gastrointestinal processes are found in the caudal part.[1][2]

Contents

·?1Inputs

·?2Outputs

·?3Additional images

·?4See also

·?5References

·?6External links

Inputs[edit]

·?Taste information from the?facial nerve?via the?chorda tympani?(anterior 2/3 of the tongue), glossopharyngeal nerve (posterior 1/3) and vagus nerve (small area on the epiglottis)

·?Chemoreceptors and mechanoreceptors of the general visceral afferent pathway (GVA) in the?carotid body?via glossopharyngeal nerve,?aortic bodies, and the?sinoatrial node, via the vagus nerve

·?Chemically and mechanically sensitive neurons of the general visceral afferent pathway (GVA) with endings located in the heart, lungs, airways, gastrointestinal system, pharynx, and liver via the glossopharyngeal and vagus nerves. Additional minor GVA input from the nasal cavity, soft palate and sinus cavities enters via the facial nerve.[3]

Neurons that?innervate?the SN mediate the?gag reflex, the carotid sinus reflex, the aortic reflex, the cough reflex, the baroreceptor and chemoreceptor reflexes, several respiratory reflexes and reflexes within the gastrointestinal system regulating?motility?and secretion.

(可能指的是打噴嚏這樣的本能反應(yīng)由solitary nucleus來觸發(fā)。)

Neurons which transmit signals about the gut wall, the stretch of the?lungs, and the dryness of?mucous membranesalso innervate the SN.

（dry mucous membrane hurt easily, then this pain information is sent in to excite parasympathetic system in order to secrete more mucus.）?

The first central neurons within the SN can participate in simple autonomic reflexes.

Outputs[edit]

Information goes from the solitary nucleus to?a large number of other regions of the brain including the?paraventricular nucleus?of the?hypothalamus?and the?central nucleus of the amygdala

(對于central nucleus，這應(yīng)該是在打噴嚏這樣的本能反應(yīng)時激發(fā)吧),

as well as to other nuclei in the brainstem (such as the?parabrachial area, the?locus coeruleus, the?dorsal raphe nucleus, and other visceral motor or respiratory networks).[4]?The signals projected from the SN to the parabrachial area originate in the oral cavity and gastrointestinal tract. The pathways for gastric and gustatory (taste) processes are believed to terminate in different subdivisions of the parabrachial area, but still interact in the SN.[5][6]?Some neuronal subpopulations in the SN, such as the?noradrenergic cell group A2?and the?aldosterone-sensitive?HSD2 neurons?project as far ventral as the?bed nucleus of the stria terminalis.[7][8]

（自主神經(jīng)系統(tǒng)的各個器官由smooth muscle和gland組成，并且其活動由位于脊髓以外的自主神經(jīng)節(jié)控制，雖然自主神經(jīng)系統(tǒng)高度自治，仍然會將系統(tǒng)中收集的sensory information上傳到中樞系統(tǒng)--即solitary nucleus，并且接受中樞系統(tǒng)中相應(yīng)核團(tuán)的控制--即preganglionic nuclei。所謂的sensory information主要來自于平滑肌的被動擴(kuò)張，可以回憶一下憋尿的膀胱帶來的感受，食物落入食道中使管壁的平滑肌擴(kuò)張，這些感受都能很明顯地影響人的感受，但是食物在小腸內(nèi)的活動應(yīng)該是小腸主動運(yùn)動的結(jié)果，而不同于胃被動地接收食物，所以說我們能夠明顯感覺到胃以及十二指腸的存在（胃酸能與十二指腸中的堿性液體中和產(chǎn)生二氧化碳），但是很難感覺到小腸的存在，可但是，吃了太多油膩食物而導(dǎo)致食物快速從小腸滑過，你就會感覺到自己有些異樣，有些暈，然后就是粑粑比平時來的更早一些、更順暢一些，原因在于：solitary nucleus的一個輸出到達(dá)locus coeruleus和dorsal raphe nucleus，于是大量來自小腸的sensory information興奮solitary nucleus進(jìn)而興奮locus coeruleus的抑制型細(xì)胞而抑制locus coeruleus從而使大腦皮層、丘腦興奮度降低，興奮dorsal raphe nucleus從而進(jìn)一步使得大腦皮層的興奮度降低，人就感覺外界事物有些奇怪，自己有些暈的乎。

其實(shí)，對于去甲腎上腺素在大腦中的分泌濃度，教科書中指出在飽食之后濃度極低，但是沒有給出濃度低的原因。其實(shí)當(dāng)我了解到solitary nucleus輸出到locus coeruleus時，我立馬就意識到solitary nucleus的這個軸突輸出應(yīng)該是興奮型遞質(zhì)，但是卻起到抑制locus coeruleus的作用，從而強(qiáng)烈抑制住了NE放大環(huán)路，這僅僅是在胃內(nèi)食物流向小腸時才強(qiáng)烈激發(fā)solitary nucleus，并不影響DA system來控制行為，只要腦島做好抑制central nucleus的工作。飽食狀態(tài)下，如果還出現(xiàn)central nucleus明顯活動，這樣就意味著central nucleus抑制抑制型神經(jīng)元，從而讓locus coeruleus活動，允許交感系統(tǒng)活動，讓NE放大環(huán)路隨時被激發(fā)，從而興奮交感系統(tǒng)，從而抑制飽食狀態(tài)下的副交感系統(tǒng)，導(dǎo)致食物在胃內(nèi)停滯不前，集聚的食物不停刺激胃，但是胃卻不分泌保護(hù)胃粘膜的粘液，然后有可能胃粘膜受損，激發(fā)嘔吐反應(yīng)。這是一個不好的NE放大系統(tǒng)的惡性循環(huán)狀態(tài)，這種狀態(tài)多發(fā)于胃內(nèi)食物過多，需要轉(zhuǎn)變到DA系統(tǒng)模式，讓腦島控制住central nucleus，也就是說改變腦島對外界食物的看法，如果腦島覺得外界對自己有威脅，就激活NE放大環(huán)路，如果腦島對外界有好感，就抑制NE放大環(huán)路。）