Thoracic Vertebrae

The vertebral foramina are smaller and more rounded than those in the cervical region, and so conform to the reduced size and more circular shape of the spinal cord in the thoracic region. They are bounded by the posterior surfaces of the vertebral bodies and by the pedicles and laminae forming the vertebral arches. The stout pedicles are directed backward; they have very shallow superior and much deeper inferior vertebral notches. The laminae are short, relatively thick, and partly overlap each other from above downward. The typical thoracic superior articular processes project upward from the junctions of the pedicles and laminae, and their facets slant backward and slightly upward and outward. The inferior articular processes project downward from the anterior parts of the laminae, and their facets face forward and slightly downward and inward. The processes and facets in the cervicothoracic and thoracolumbar junctional areas show gradual transitional changes.

Most of the thoracic spinous processes are long and are inclined downward and backward. Those of the upper and lower thoracic vertebrae are more horizontal. The transverse processes are also relatively long and extend posterolaterally from the junctions of the pedicles and laminae. Except for those of the lowest two or, occasionally, three thoracic vertebrae, the transverse processes have small oval facets near their tips, which articulate with similar facets on the corresponding rib tubercles.

Adjacent vertebral bodies are connected by intervertebral disks and by anterior and posterior longitudinal ligaments; the transverse processes, by intertransverse ligaments; the laminae, by ligamenta flava; and the spinous processes, by supraspinal and interspinal ligaments. The joints between the articular processes are surrounded by fibrous articular capsules.

Costovertebral Joints. The ribs are connected to the vertebral bodies and transverse processes by various ligaments. The costocentral joints between the bodies and rib heads have articular capsules, and the second to tenth costal heads, each of which articulates with two vertebrae, are connected to the corresponding intervertebral disks by intra-articular ligaments. Radiate (stellate) ligaments unite the anterior aspects of the rib heads with the sides of the vertebral bodies above and below, and with the intervening disks.

The costotransverse joints between the facets on the transverse processes and on the tubercles of the ribs are also surrounded by articular capsules. They are reinforced by a (middle) costotransverse ligament between the rib neck and the adjoining transverse process, a superior costotransverse ligament between the rib neck and the transverse process of the vertebra above, and a lateral costotransverse ligament interconnecting the end of a transverse process to the nonarticular part of the related costal tubercle.

Only gold members can continue reading. Log In or Register to continue