Practical anatomy: a manual of dissections / by Christopher Heath.
- Christopher Heath
- Date:
- 1870
Licence: Public Domain Mark
Credit: Practical anatomy: a manual of dissections / by Christopher Heath. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
509/600 (page 499)
![tened enlargements, one the bracJiiaJ, which extends from the third cervical to the first dorsal vertebra, and the lower or lumbar enlargement near the lower extremity of the cord. From the upper enlargement the nerves to the upper extre- mity have their origins; from the lower enlargement the lumbar and sacral nerves arise, which, lying side by side before they leave the vertebral canal, form the cauda equina. The cord presents an anterior median fissure which ex- tends for its whole length, and a posterior median fissure which is most distinct at the upper and lower parts of the cord. A lateral fissure extends along the line of attachment of the posterior roots of the spinal nerves, thus dividing each half of the cord into an antero-lateral and a posterior column. The anterior roots of the nerves emerge from the antero- lateral columns, and these are sometimes considered to mark a further subdivision into anterior a.\\d lateral columns. At the bottom of the median fissures is the commissure, which is nearer to the anterior than the posterior surface of the cord. The Spinal Nerves (Fig. 229) are thirty-one in number on each side of the cord. Each nerve has been seen to arise by two roots, the posterior (with the exception of the first nerve) being larger than the anterior. The posterior roots have each a ganglion which is generally placed in the inter- vertebral foramen, at which point [but just beyond the gan- glion] the anterior (motor) and posterior (sensory) roots unite to form a spinal nerve of mixed endowments. The first two cervical, with the sacral and coccj^geal nerves, are exceptions to the general rule as regards the position of the ganglia. The ganglia of the two cervical nerves lie upon the arches of the atlas and axis, at which points the roots of the nerves unite. The ganglia of the sacral and coccygeal nerves are within the sacral canal. Each spinal nerve divides into an anterior anda poste- rior trunk, the anterior divisions being the larger through- out, with the exception of the 1st and 2d cervical nerves of which the posterior is larger than the anterior division. The majority of the spinal nerves divide just outside the intervertebral foramina, but in the first cervical, the last sacral, and the coccj'geal nerves the division takes place within the dura mater; and the upper four sacral nerves divide within the sacral canal, the anterior and posterior](https://iiif.wellcomecollection.org/image/b21057679_0509.jp2/full/800%2C/0/default.jpg)
