. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 634 NERVOUS SYSTEM. (NERVOUS CENTRES. THE MENINGES.) fibrous tissue, which cannot confer elasticity. And if a portion removed from the cord be stretched, it will be found to possess very little elasticity; but if the cord be held up by the filiform prolongation, and a slight jerking move- ment be communicated to it, it may be made to dance about as if by the elastic reaction of the filliform process. The movement which may be thus produced is very well calculated to deceive, and Dr. Macartney must have founded his opinio
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 634 NERVOUS SYSTEM. (NERVOUS CENTRES. THE MENINGES.) fibrous tissue, which cannot confer elasticity. And if a portion removed from the cord be stretched, it will be found to possess very little elasticity; but if the cord be held up by the filiform prolongation, and a slight jerking move- ment be communicated to it, it may be made to dance about as if by the elastic reaction of the filliform process. The movement which may be thus produced is very well calculated to deceive, and Dr. Macartney must have founded his opinion upon that experiment alone, omitting to try the effect of stretching a detached portion of the process. The fact is that when the cord is suspended in this way, the pia mater becomes stretched, and its anterior and posterior por- tions are approximated and the cord flattened ; when it is raised with a jerk, this tension of the pia mater is diminished, and the cord re- turns to its previous form until it falls again, stretches the pia mater, and becomes once more flattened, producing a degree of reaction which favours its elevation, but which alone would be insufficient for that purpose. Thus it appears that the elastic reaction, which Dr. Macartney attributed to the filiform process, is in reality due to the compression and conse- quent flattening of the cord by the tension of the pia mater. It should be stated, further, that this process is not formed of pia mater alone, but also of a continuation of the liga- mentum denticulatum on each side to be described by-and-bye. The pia mater is abundantly supplied by bloodvessels, many of which are extremely tortuous. These vessels are derived from the anterior and posterior spinal arteries. Along the anterior surface of the spinal cord in front of the anterior median fissure there is a narrow band of fibrous tissue which is stretched across this fissure like a bridge, and occupies its whole length. No such arrangement exists on th
Size: 1741px × 1435px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjectphysiology, booksubjectzoology
