Thoracic Spine

The thoracic spine consists of 12 vertebrae. The vertebral bodies gradually become higher and wider as they move toward the lumbar spine. The vertebral hole is approximately round and smaller than in the cervical and lumbar spine, the end faces are rounded and triangular.

Since the spinous processes are long and strongly bent downwards towards the back, the thoracic vertebrae are interlocked in a special way (like roof tiles). The ribs attach to the thoracic vertebrae, which is why they are equipped with cartilaginous joint surfaces both on the vertebral bodies and on the transverse processes. This results in two rib-vertebral joints: the costal head joint and the costal hump joint.

The former is formed in the 2nd -10th rib by two superimposed thoracic vertebrae and the rib head with its joint surfaces. In the 1st, 11th and 12th rib, only one thoracic vertebra articulates with the rib head. All joint capsules of the rib head joints are reinforced by ligaments.

In the rib hump joints of the 1st -10th rib, the rib humps articulate with the joint surface of the corresponding transverse process of the thoracic vertebra. A corresponding joint is missing in the 11th and 12th ribs, since the transverse processes of these thoracic vertebrae have no joint surfaces. These joints are also strengthened by a total of 3 ligaments.

They run not only between the ribs and their associated thoracic vertebrae but also between the neck of the ribs and the transverse process of the next higher vertebra. Both rib joints are morphologically completely separated from each other, but form a unit in their mobility. In the lumbar spine, the rib systems in the form of the transverse processes are much stronger than in the cervical spine.

Therefore, the transverse processes in this area are also called rib processes. Additional ribs may occur, but usually do not cause any discomfort. On the other hand, an additional cervical rib can constrict the plexus of the arm nerves and the accompanying artery, resulting in the so-called scalenus or cervical rib syndrome.

The lumbar spine has 5 strong vertebral bodies that are transverse-oval in plan view. Their bulky vertebral arches enclose an almost triangular vertebral hole and unite to form a strong, flattened spinous process. Due to the upright gait, the lumbar spine in particular is subject to enormous weight.

This load can lead to various clinical pictures. From unspecific pain and degenerative changes to the dangerous herniated disc, which is frequently found in this area, the lumbar spine is particularly prominent in the eyes of clinicians. The interior of the spinal canal conceals a special feature of the lumbar spine, or rather the spinal cord running through it.

In most people, this ends at the level of the 2nd lumbar vertebral body. This fact goes back to the history of human development. Until the 12th week of development in the womb, the spinal cord and the spinal canal are of equal length, so that spinal nerve pairs emerge through the intervertebral hole, which is at the same height.

With age, however, the spinal column grows faster than the spinal cord, so that already at birth the spinal cord ends at the level of the 3rd lumbar vertebra. The consequence of this different growth is that the spinal roots of the nerves move diagonally downwards in the spinal canal to their respective intervertebral holes and emerge there. As a whole, these roots are collectively referred to as the so-called “ponytail” (cauda equina).

Although there are no longer any spinal cord segments in this area, the sheaths or skins surrounding the spinal cord still extend into the sacral canal. This is the reason why cerebrospinal fluid (brain and spinal cord fluid) can be safely removed in this area. This lumbar puncture is used for the diagnosis of various diseases.Likewise, an anesthetic can be applied in this area during a surgical procedure to eliminate pain and muscle paralysis for the lower extremity and the pelvic region (spinal lumbar anesthesia).