Kitap 8
1
Now the spine is the support of the head. It is composed of twenty-four vertebrae, seven in the neck, twelve belonging to the ribs; the remaining five are below the ribs. The vertebrae are bones rounded off and short; from each side they thrust out a transverse process; they are perforated in the middle where the spinal marrow which is connected with the brain passes downwards, and at the sides also through the two transverse processes they are traversed by fine channels, through which little membranes pass down resembling the cerebral membrane; with the exception of the three highest all the vertebrae have slight depressions in their articular processes on the upper side, on the lower side other articular processes grow downwards. The highest vertebra is therefore the immediate support of the head, receiving its small processes into two depressions, and this enables the head to move up and down. The second vertebra is made irregular by a protuberance and is attached to the lower side of the one above. To secure the rotation of the head the top of it ends in a narrower round process, so that the first vertebra encircling the top of this allows the head to turn sideways as well. After the same fashion the third vertebra supports the second, hence there is easy movement in the neck. And the neck could not even hold up the head were it not supported on each side by straight and powerful sinews which the Greeks call te/nontej; since whenever the head bends one of the sinews is always tense, and does not allow what is above to slip too far over. From the third vertebra in turn grow little protuberances which are inserted into the vertebra below; the remaining vertebrae are fastened into the ones below them by processes directed downwards and support the ones above them in the depression which they have on either side, and they are held together by many ligaments and cartilages. Thus by bending once in the required direction and avoiding moving in other directions man stands upright, or bends somewhat, to do anything that is required.
