In the name of God, the compassionate, the merciful. The Fifteenth Book of the writing of Galen on Anatomical Dissection.

INTRODUCTION. EXPOSURE OF SUPERFICIAL NERVES AND MUSCLES OF THE NECK.

Galen says: when surgeons speak of pairs of nerve roots, they apply the name not only to those pairs of nerves arising from the brain, but also to the paired nerves, growing out from the spinal cord, since the nerve roots are found on both sides, I mean on the right side and on the left. For branches break off either from the brain itself or from the spinal cord itself and become firmer and more dense, being braced together, and consequently they become different from the root from which they took origin. The texture of the spinal cord is just the same as that of the brain from which it starts out, but it is more indurated than the brain tissue. The degree of increase in this induration corresponds to the degree in which the nerve arising from the spinal cord is more indurated than the cord itself. It makes no difference to the exposition of Anatomy which we have in mind whether, considering the nerves arising from the spinal cord which we propose to mention here, we name the spinal cord according to the customary usage of the Greek language ‘vertebral marrow’, or simply ‘marrow’. For Plato applies the term ‘marrow’ to the spinal cord, which he calls ‘vertebral marrow’, and to the brain also, which he calls ‘cranial marrow’.