Spinal-cord

See also: Marrow

The spinal-cord , whose scientific name is marrow spinale , is the part of the central Nervous system being in lower part of the cerebral Tronc and contained in the vertebrae forming the Spinal column.

The spinal-cord contains several types of neurons:

  1. Of the nervous fibers (Neuron S) which relay sensory information since the periphery (Muscle S, Peau, internal organs) until the Cerveau.
  2. Of nervous fibers (Neuron S) which relays driving information since the Cerveau until the Motoneurone S, common final way of any act moteur.
  3. Of the neurons specific to the spinal-cord among which one finds inter alia segmentary interneurones, propriospinaux interneurones which connect various segments between them, of the commissuraux interneurones implied in coordination right-hand side-left. The Motoneurone S have stroma located to them in the spinal-cord and their axon contained in the peripheral nerves. Each Motoneurone projects on a certain number of muscle fibers. Some interneurones organized in network constitute the generating central rate/rhythm responsible for the genesis of rhythmic behaviors such as the locomotion.
Contrary to an exceeded vision, marrow is thus not a simple relay of information, but a center complexes which treats and generates nervous signals.

Embryology

Marrow spinale originates in the tube neural set up at the 4th week of development thanks to the neurulation. In the 3rd month of development, marrow spinale entirely fills the vertebral channel. But the differential growth of the osseous rachis and the central nervous system, named allometric growth , leads to a marrow stopping on the level of disc L1L2 and the formation of the tail of horse.

Anatomy

The spinal-cord is the prolongation of the central nervous system being under the trunk cerebral and contained in the rachidian channel. 45-50 cm length cylindrical stem, marrow gives rise to the rachidian nerves and ends in the tail of horse or " filum terminale" (25 cm length), true network of ramifications.

It leaves by the foramen magnum (where it makes following lengthened marrow), its higher limit is the emergence of the C1 root, and will finish compared to the 2nd lumbar vertebra (L2, or disc L1L2). One observes two medullary widenings at the cervico-thoracic level (C5-T1) and the lumbar level (T10-L5). These widenings correspond to the fiber excess present at this level and intended for the innervation of the upper limbs and inferior.

The transverse cut makes it possible to identify the presence of central gray substance according to a diagram out of butterfly defining of the horns. With the level of the former horns are born the motoneurones, while the posterior horns form the place of projection and relay of the sensitive neurons.

In the center marrow is dug by the channel of the épendyme (or channel épendymaire) which contains the céphalo-rachidian Liquide (LCS or LCR); the white substance in periphery consists of sensitive and driving fiber beams gathered in 3 cords or funiculli. The cords are observed: Ventral, Side, Dorsal The spinal-cord includes/understands very many vegetative centers, the spinal-cord is not only one zone of passage since it is in particular the center of reflex and that it preserves a relative autonomy compared to brain.

Complex functions

The spinaux neurons function according to processes closer to those of the cerebral Cortex than than one believed until the beginning of the year 2000. It was recently shown (2006/2007) that the same movement precisely reproduced could be generated by a network different of neurons to each reproduction of the movement. The spinaux neural networks thus have a random activity and not simply mechanical. Marrow seems less and less like a sheath of cables and more and more a complex prolongation of the brain.

Medullary pathologies

Seek on the spinal-cord

There are 10 more or 20 years, it was clearly established that a nerve could never push back after being divided or being wounded. Recent progress shows the opposite.

Tests on the man?

  • Dr. Huang in China operated more than 500 patients, but information which one has, were not the subject of several international publications yet, confirming the positive echoes which circulate on the forums. It seems indeed, that the effects of the establishment of the OEC (olfactory ensheathing concealments) are a fall of on average of one to two vertebrae of the level of the lesion.

  • In 2005 Dr. Lima in Portugal operated 9 patients, initially 7 Portuguese then 2 American. One starts to speak about his work, and there too there is a driving and/or sensitive recovery generally. The extent of the lesion (in cm) is determining to practice the operation. Shine, 29 years, complete lesion D4-D5, recovered after the operation its sensitivity right under its lesion, then the control of the abdominal and delivery muscles essential to hold balance upright. Florbela, 32 years, will tétra C6, recovered in the seven months after the operation, its muscles abdominal, the sensitivity of the left leg, and lastly at it, the possibility of clutching with its fingers. Agreements with an American service of readjustment will allow the best followed and a better rehabilitation of the patients operated by Dr. Lima, which was not the case for the 7 first.

  • an Australienne team of Brisbane initiated a series of tests phase 1, using about the same technique. Little information filters for the moment, for reasons of scientific validation, the name, the sex of the 8 voluntary patients are not diffused. It is inter alia Dr. Féron, neurobiologist French, who is at the origin of these tests, as well as the results of the experiments on the rats of the Spanish team of Drs Cueto and Sampedro.

  • In the United Kingdom, the team of Dr. Raisman wishes to initiate a phase of clinical trial of establishment of OEC. He considers that all preliminary work necessary was carried out, in particular in animal experimentation, and that it is time to pass to the human tests. Its study is published in the " newspaper off the Royal Society off Medicine".

Source: Site of the free association of assistance to research on the spinal-cord: http://alarme.asso.fr More information on the topicality of world research on the spinal-cord on the forum: http://alarme.asso.fr/forum

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