Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 15 On the Vertebrae of the Neck or Cervix

A different opinion from Galen’s about the motions of the head

In the first place, we move the head either with a primary motion in which the neck holds still, or with a secondary motion, where the head follows the motion of the neck even if you try to move it in a different direction from the neck. There are two movements peculiar to the head: in one, we bend it forward and incline it backward, or extend it. You perform this motion with a rigid, unmoved neck or with a neck moved simultaneously, whether you do it with a motion equal with the head, or a contrary motion. For although you move the neck forward and the head necessarily follows the neck, still you can bend the head backward with its own motion and easily observe that the head and neck have their separate and distinct motions in bending and unbending. The other peculiar movement of the head should be counted that by which we rotate it more or less as if we were spinning it as a wheel is turned on an axle. You will undergo this motion without moving the neck, whether you have tried to look left or right, or rotated the head. This motion is completely confined to the head: the neck does not have it. Therefore, however you move the neck, this rotation of the head is easily accomplished. For when the neck is bent and the head is inclined


page 64

with it, you can easily move it in rotation. So even if the neck shall have been extended or moved sidewise to the shoulder, you can readily rotate the head. As the head possesses a single motion of rotation which the neck lacks, so the neck claims another motion peculiar to itself, by which it is moved to the side. The head has no motion of its own by which it is inclined to the side, but is moved to the side only by the neck in a secondary motion. Indeed, it is denied us to move the head even a little to this or that scapula except as it is taken that way by the neck.



Book One -- The things that sustain and support the entire body, and what braces and attaches them all. [the bones and the ligaments that interconnect them] | Chapter 15 On the Vertebrae of the Neck or Cervix