Thoracic Vertebrae: Structure, Function & Diseases

Thoracic vertebrae are the twelve bony components of the middle spine. The main functions of this thoracic spine are to stabilize the upper body and protect the heart and lungs. Diseases such as osteoporosis can damage the thoracic vertebrae and cause a painful hunchback.

What are thoracic vertebrae?

In medicine, thoracic vertebrae are the bony parts of the thoracic spine. A person is equipped with a total of twelve thoracic vertebrae. These vertebrae are numbered in descending order. According to this scheme, the individual vertebrae are called Th one to twelve. All thoracic vertebrae consist of a vertebral body, a vertebral arch and vertebral processes. The thoracic spine is an integral part of the middle spine and plays a role in the structure of the rib cage in particular. The individual vertebrae are in contact with the ribs and form the basis for the attachment of rib-vertebral joints as well as individual muscle groups. All thoracic vertebrae are structurally relatively similar and interconnected. Animals are also equipped with thoracic vertebrae. However, they differ from human thoracic vertebrae. Horses, for example, have 18 thoracic vertebrae. Goats and sheep, on the other hand, have 13. However, the tasks and shape of animal thoracic vertebrae again resemble human anatomy.

Anatomy and structure

Vertebral bodies are short and cylindrically shaped vertebral components and make up the main mass of a thoracic vertebra. Below each other, these vertebral bodies are connected by so-called intervertebral discs. Near the back surface of the vertebral body, each vertebral body carries a vertebral hole that provides space for the spinal cord and its vessels or nerves. This vertebral hole is largely enclosed by the arched base of the vertebral arch. The vertebrae are aligned via the vertebral hole and form the so-called vertebral canal. The spinal nerves pass through the resulting intervertebral hole. The vertebral arch feet correspond to the bony boundary. The thoracic vertebrae differ from the other vertebrae of the spinal column in that they bear a rather round vertebral hole. In the middle region of the thoracic spine, the holes are also much smaller than those in the rest of the spine. Attached to the vertebral arch of each thoracic vertebra are lateral vertebral processes. The lateral processes are also called transverse processes. The dorsal ones are called spinous processes. In addition to the two transverse processes and one spinous process, each thoracic vertebra has two articular processes above and below, as well as two articular surfaces to the ribs. The rib-vertebral joints are stabilized by many ligaments, such as the ligamentum capitis costae radiatum.

Function and tasks

Thoracic vertebrae form multiple articular surfaces. Adjacent thoracic vertebrae, for example, are articulately connected to each other via the flat portion of the vertebral arch. This articulated connection exists in four forms per vertebra. Together with the so-called rib heads, the thoracic vertebrae also form the rib-vertebral joint. In this respect, the joint groups of two thoracic vertebrae lying one above the other each take up the head of a rib. Only the first, eleventh and twelfth thoracic vertebrae are not involved in a rib-vertebra joint. Articulatingly, the transverse processes of thoracic vertebrae one through ten are also connected to the costal tuberosity. Some of these articulations are concave, while others of them are planar. The joints of the thoracic spine are partially involved in flexion and extension, lateral flexion and rotation. In fact, flexion and extension of the trunk is made possible mainly by the joints of the thoracic spine. When leaning forward, the thoracic spine curves. In contrast, it flattens out during backward flexion. The thoracic spine is also involved in the lateral flexion of the trunk. The same applies to the rotation of the upper body. Compared to the cervical spine or the lumbar spine, however, the thoracic spine is much less flexible because it is firmly bound to the rib cage at every level. This tight binding supports the upper back and provides extensive upper body stability. As such, the thoracic spine is responsible in no small part for keeping the upper body upright. In addition, this part of the spine also protects the internal organs of the chest area, so especially the lungs and heart.

Diseases

Injuries to the thoracic spine are less common than those to the lumbar or cervical spine.However, bone metastases resulting from tumor disease are most frequently found in the thoracic spine and can be clarified by means of skeletal scintigraphy. Since the spinal canal in the thoracic spine is quite narrow, injuries in this area in particular are often extremely serious and can thus cause paraplegia, for example. Accidental fractures do occur, but are not particularly common. However, diseases can certainly affect the thoracic spine. In most cases, disease-related complaints of the thoracic spine manifest themselves in the form of a rounded back or an increased curvature of the back. Scoliosis, Scheuermann’s disease or osteoporosis can affect the individual thoracic vertebrae. In medicine, scoliosis is a growth deformity in which there is a lateral deviation of the spine. Scheuermann’s disease, on the other hand, is an ossification disorder of the spine. As part of this phenomenon, the anterior portions of the thoracic vertebrae grow more slowly than the posterior portions until the age of 18. The resulting deformities are usually accompanied by severe back pain. If, on the other hand, osteoporosis attacks the thoracic spine, disease-related fractures of the vertebrae occur. In most cases, these vertebral fractures are located in the lower part of the thoracic spine. If the spinal canal is narrowed in the process, radiating pain and sometimes even paralysis occur.