The thoracic spine is the second segment of the vertebral column, located between the cervical and lumbar vertebral segments. It consists of twelve vertebrae, which are separated by intervertebral discs, forming part of the thoracic cage which helps to protect the internal organs such as the heart, lungs, and oesophagus. This article will examine the characteristic features, joints, and clinical correlations of the thoracic vertebrae.
The thoracic vertebrae have four features that distinguish them from other vertebrae: a heart-shaped vertebral body, demi-facets located on the sides of each vertebral body which articulate with the heads of the ribs, costal facets on the transverse processes that articulate with the tubercles of the ribs from T1 to T10, and slant inferiorly spinous processes which offer increased protection to the spinal cord.
The superior and inferior costal facets are located on the sides of each vertebral body. They consist of cartilage lined depressions, which articulate with the heads of the ribs. The superior facet articulates with the head of the adjacent rib, and the inferior facet articulates with the head of the rib below. In the majority of the vertebrae (T2-T9), these facets are demi-facets; however, some atypical vertebrae possess whole facets.
The atypical thoracic vertebrae display variation in the size, location, and number of their superior and inferior costal facets. For example, T1 has a superior facet which is not a demi-facet, as this is the only vertebrae to articulate with the 1st rib; T10 has a single pair of whole facets which articulate with the 10th rib, located across both the vertebral body and the pedicle; T11 and T12 each have a single pair of entire costal facets, located on the pedicles.
The joints of the thoracic spine can be divided into two groups - those that are present throughout the vertebral column, and those unique to the thoracic spine. Joints present throughout the vertebral column are between vertebral bodies and vertebral arches, both of which are a type of cartilaginous joint (e.g. symphysis and synovial type). The articulations between the vertebrae and the ribs are unique to the thoracic spine, and consist of two separate articulations, costovertebral and costotransverse.
Each costovertebral joint consists of the head of the rib articulating with the superior costal facet of the corresponding vertebra, and the inferior costal facet of the superior vertebra, as well as the intervertebral disc that separates the two vertebrae. Intra-articular ligament of head of rib attaches the rib head to the intervertebral disc, allowing only slight gliding movements to occur at these joints due to their close articulation.
The costotransverse joints are formed by the articulation of transverse processes of a thoracic vertebra and the tubercle of the adjacent rib, though this is not present in T11 and T12. The thoracic spine is strengthened by the presence of numerous ligaments.
The thoracic spine is a complex structure, and it is important to be aware of the clinical implications of any injury or ailment occurring in this region of the body. For example, fractures of the thoracic vertebrae can lead to severe and permanent disability, while thoracic vertebral body collapse can cause irritation of the spinal cord or nerve roots, resulting in chronic lower back and/or leg pain.
Rib fractures can be particularly serious, as they are associated with the high rate of lung injury. Due to the close relationship of the ribs with the thoracic spine, any trauma or dysfunction of the ribs can result in considerable pain and difficulty in movement. Furthermore, certain diseases such as tuberculosis, which affect the thoracic spine, can result in bone and joint destruction and deformities, leading to long-term limitations.
As such, having an understanding of the structure and function of the thoracic spine is important in diagnosing and treating any diseases or injuries that may arise. In particular, if the patient experiences chronic back pain, it is essential to perform a thorough assessment of the thoracic spine in order to determine the cause.
The thoracic spine is a complex and important structure, and plays a vital role in the functioning of the body. It is important to understand its anatomy, so as to recognize and treat any injuries or diseases that may affect it. In particular, physicians must be vigilant when assessing and treating patients with chronic lower back pain, as this could be a symptom of a serious underlying condition.
The majority of thoracic vertebrae (T2 to T9) possess superior and inferior costal facets, which consist of cartilage-lined depressions that articulate with the heads of the ribs. However, the atypical thoracic vertebrae (T1, T10, T11 and T12) may demonstrate variation in the size, location and number of these facets. T1 has a single superior costal facet, while T10 and T11 have a single pair of entire facets located across both the vertebral body and pedicle, and T12 has a single pair of entire costal facets located on the pedicles.
The joints of the thoracic spine can be divided into two groups – those that are present throughout the vertebral column, and those unique to the thoracic spine. Those present throughout the vertebral column include:
Those unique to the thoracic spine include costovertebral and costotransverse joints, which are formed by the articulation of the head of the rib, superior and inferior costal facets, intervertebral disc and transverse process. Each costovertebral joint consists of the head of the rib articulating with the superior costal facet of the corresponding vertebra, inferior costal facet of the superior vertebra and the intervertebral disc separating the two vertebrae. Within this joint, the intra-articular ligament of head of rib attaches the rib head to the intervertebral disc.
The costotransverse joints are formed by the articulation of transverse processes of a thoracic vertebra and the tubercle of the adjacent rib. They are present in all vertebrae except T11 and T12, and are stabilized by several small ligaments. These include the radiate ligament of head of rib, which fans outwards from the head of the rib to the bodies of the two vertebrae and intervertebral disc; the costotransverse ligament, which connects the neck of the rib and the transverse process; and the lateral and superior costotransverse ligaments, which extend from the transverse process to the tubercle of the rib, and from the upper border of the neck of the rib to the transverse process of the vertebra superior to it, respectively.
The presence of long, slanted spinous processes on the thoracic vertebrae offers increased protection to the spinal cord, preventing the entry of an object such as a knife into the spinal canal. Lastly, each thoracic vertebra also possesses costal facets on its transverse processes, which articulate with the tubercles of the ribs (T1 to T10 only).
Kyphosis is an excessive curvature of the thoracic spine, causing the back to appear “hunched”. It may occur for a number of reasons early in life, including poor posture, abnormally wedge-shaped shaped vertebrae (Scheuermann’s kyphosis), and fusing of vertebrae during development. Various diseases can also lead to kyphosis in adults, with the most common cause being osteoporosis – a condition whereby bone mass is lost (mostly in older people), leaving the spine less able to support the weight of the body and causing characteristic kyphosis.
The thoracic spine is comprised of twelve vertebrae, which are located between the cervical spine and lumbar spine in the vertebral column. The osteology of this region involves eight pairs of ribs, two sternum parts, the costal cartilages, multiple joints, ligaments, and other muscles. Intervertebral discs, lamina, and joints are some of the main anatomical features that can be relevant to its clinical correlations. Furthermore, the thoracic spine is associated with thoracic kyphosis, a condition in which an increased curvature of the spine in the thoracic vertebrae occurs.
The thoracic spine is strengthened by the presence of numerous ligaments, including:
There are also a number of small ligaments that support the costovertebral joints, such as:
Kyphosis is an excessive curvature of the thoracic spine, causing the back to appear “hunched”. It can be caused in adolescence due to poor posture, or a wedge-shaped vertebrae (Scheuermann’s kyphosis). Fusing of vertebrae during development can also be the reason for kyphosis. In adults, osteoporosis is the most common cause of kyphosis. Osteoporosis is a condition in which bone mass is lost, mostly in older people. This leaves the spine less able to support the weight of the body, thus resulting in a characteristic hunched posture.
The thoracic spine is a complex anatomical region made up of numerous ligaments, joints, vertebrae, and other structures. These anatomical features can be used to understand the pathological condition of thoracic kyphosis. Poor posture, abnormally shaped vertebrae, and fusing of vertebrae during development can cause the condition in adolescents, while adult-onset kyphosis is usually attributed to osteoporosis.
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