Now that we’ve looked at one vertebra, let’s look at the specialized and different features of vertebrae from the cervical, thoracic, and lumbar parts of the spine.
Here’s a typical cervical vertebra, the fourth one. The body is small. The upper surface of the body is curved, somewhat in the shape of a saddle. The lower surface has the same curvature in reverse.
The vertebral foramen is large and triangular. The neural arch is formed mainly by the two straight laminae. The pedicles are very short. The spinous process is short, and ends in a double point.
The upper articular facets face upward and inward, the lower ones face downward and forward. The mass of bone between the articular facets is called the articular pillar.
The transverse processes arise from the side of the body, and also from here on the articular pillar. The transverse process of a cervical vertebra has a hole in it, the transverse foramen, through which the vertebral artery passes.
The transverse process is shaped like a gutter, pointing downwards. It ends in two tubercles, an anterior, and a posterior, where the scalene muscles attach.
Of the seven cervical vertebrae, the first two, which are called the atlas and the axis, differ from the others in several ways. We’ll see them in detail in Volume 4 of this Atlas. The seventh cervical vertebra also differs from the others, in that it has a long spinous process ending in a single point, which forms this small prominence on the back of the neck.
The cervical vertebrae form the most mobile part of the spine, partly because of the curved shape of their bodies, which makes flexion and extension easy and partly because of the shallow slope of their articular processes, which makes lateral flexion easy. The movements that can occur in the cervical spine are forward flexion, extension, and lateral flexion, to one side or the other.
Rotation also occurs in the neck. Almost all of it happens at the specialized joints between the atlas and the axis vertebrae, which we’ll look at in the tape on the head and neck,Volume 4 of this atlas. In that tape we’ll also look at the way the atlas vertebra articulates with the bone which forms the underside of the skull, the occipital bone. The joints between the atlas and the occipital bone are called the atlanto-occipital joints.
Next we’ll look at the special features of the thoracic vertebrae. The bodies of the thoracic vetebrae become progessively more massive from above down, as they do from the top to the bottom of the vertebral column.
Each of the thoracic vertebrae articulates with a pair of ribs. On each side, the vertebra articulates with the rib at two points: here at the end of the transverse process, and here, where the pedicle meets the body. We’ll be looking at the ribs in the second section of this tape.
The transverse processes of the thoracic vertebrae point sideways, the spinous processes points downwards, each one overlapping the one below. The articular processes are almost vertical: the upper ones face almost straight backwards, the lower ones face forwards.
There’s only a little movement between thoracic vertebrae, partly because of the presence of the ribs, and partly because of the way the spinous processes are arranged.
The movements that are possible are small amounts of forward flexion, lateral flexion, and perhaps surprisingly, rotation.