The anatomy of spina bifida / by Professor Humphry.

  • Humphry, George Murray, Sir, 1820-1896.
Date:
[1855]
Catalogue details

Licence: Public Domain Mark

Credit: The anatomy of spina bifida / by Professor Humphry. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    specimen is a small spina bifida at the lower part of the sacrum, and the median filament of the cord and the nerves seem to be at the fore part of the sac; but further dissection is necessary to make the anatomy clear. In the College of Surgeons’ museum is a specimen from an infant who died three days after the application of a ligature to a cervical spina bifida. The narrow peduncle of the sac passes through between the sixth and seventh cervical spinous processes, which are almost fully developed, and nearly meet in the middle line. The cavity of the sac appears, from the direction of a bristle placed in it, to communicate with the hinder part of the arachnoid cavity, and the cord possibly is not in the least degree implicated, and passes free along the hinder surface of the bodies of the vertebrae. But further dissection is required to make sure of this. It may be, as in an apparently similar case represented in Forster’s Misshildnngen, that the affection consists in a dilatation of the central spinal canal, and that a thin dilated sheet of the hinder part of the cord is prolonged into the wall of the sac^—that is to say, it may be an example of “hydrorachis interna.” ^ This can only be determined, if in such a specimen it can be determined at all, by removing the dura mater, and making a care- ful examination of the parts. Whether the sac in this case was covered by skin or not cannot be seen. In cases of cervical spina bifida, occasionally met with, in which the sac has a narrow neck, and is covered by skin, the disposition is probably similar to that in the specimen just referred to. Like it, such cases furnish examples of the slightest degree of the malformation; and the examination of a larger number of specimens of the kind may enable us to judge what inference, as to the disposition of the cord and its relations to the sac, may be drawn from the presence of a covering of skin over the sac—whether, that is to say, the segmentation and development which have produced skin over the surface are associated with a corresponding segmentation and development of the cord sufficient to set it, with its pia mater and arachnoid, free from the sac, or so far free as to allow it to maintain its proper place in contact with the bodies of the vertebrae. The fluid, as I have already said, appears commonly to be in the subarachnoid space in front of the cord; and the sac must in such cases, I conclude, be lined by an endothelium developed from that of the subarachnoid lymph spaces. In some instances the fluid is in the arachnoid cavity in front of the cord, and then the sac is lined by the endothelium of the arachnoid. In hydrorachis interna, where the sac is formed by a dilatation of the central spinal canal, the epithelial lining of the sac will be continuous with that of the central canal. The fluid may be, though this rarely is so, in the subarachnoid 1 That is the case in a well-preserved and well-dissected specimen in the Musee Dupiiytren in Paris. There is hydrocephalus and a spina bifida sac at the .seventh dorsal vertebra. The spinal cord is normal above and below this point. At this j)oint it is bent a little backwards towards the sac, and the hinder part of it is connected with, apparently expanded over, the sac. Some of the nerve fibres, those ajiparently from the posterior roots, have been exposed by dissection in the wall of the sac ; and it is stated that the cavity of the sac is continuous with the canal of the cord.