They also lack facets on the transverse processes. Ann Wiles. The thoracic vertebrae are bones located between the cervical and lumbar vertebrae. During puberty, five secondary ossification centers develop at the tip of the spinous process and both transverse processes, and on the superior and inferior surfaces of the vertebral body. The point at which superior and articular facets meet is known as a facet, or zygapophyseal, joint. These plexuses are valve-less and allow for the movement of blood superiorly or inferiorly depending on pressure gradients. The term anterior refers to the front of the spine. Therefore, it requires a greater amount of energy (force of trauma) to produce fractures and dislocations. It consists of twelve vertebrae, which are separated by intervertebral discs. Figure 3: costovertebral joints (Gray's illustration), Figure 4: costotransverse joints (Gray's illustration), Figure 5: lateral spine anatomy (Gray's illustration), https://sites.google.com/site/caduceusnewsletter/medical-reference/ann-s-acronyms-t-versus-d---by-ann-wiles, accessory ossicle of the anterior arch of the atlas, posterior inferior cerebellar artery (PICA), inferior interventricular artery (posterior descending artery), medium-sized, heart shaped vertebral bodies, prominent transverse processes with costal facets, long spinous processes angulating downwards. The thoracic spine is made up of 12 vertebrae, each referred to by 'T', with an identifying number appended to it. Spinal veins form venous plexuses inside and outside the vertebral canal. 2018 Jan, Waxenbaum JA,Futterman B, Anatomy, Back, Cervical Vertebrae null. The thoracic spine (often shortened to T-spine) forms the middle part of the vertebral column. The ossification centers on the vertebral body are responsible for the superior-inferior growth of the vertebrae. Thoracic vertebrae have superior articular facets that face in a posterolateral direction. Typical thoracic vertebrae have several features distinct from those typical of cervical or lumbar vertebrae. The zygapophyseal joints, as well as the relatively thin intervertebral discs, cause the thoracic region to have the least flexion/extension ability of the spine. The middle 12 vertebrae make up the thoracic spine. They ossify from three primary ossification centers: one in the endochondral centrum (which will develop into the vertebral body) and one in each neural process (which will develop into the pedicles). This guide gives a general overview of the anatomy of the thoracic spine. However, due to the orientation of the facet joints, the thin intervertebral discs, and the ribcage, the thoracic spine is functionally rigid. Each vertebra is made of the same parts. The thoracic vertebrae, as a group, produce a kyphotic curve. For a basic description of the anatomy of typical vertebrae, see vertebrae. The ligamentum flavum is a long elastic band that connects to the front surface of the lamina bones. As with all physiology, the anatomy of a structure is related directly to its function. There are 12 thoracic vertebra, termed T1-T12. There are 13 thoracic vertebrae (13 pairs of ribs) in the dog and ox, but 18 in the horse. The vertebral body consists of a trabecular bone, which contains the red marrow, surrounded by a thin external layer of compact bone. This projection gradually increases as the column descends before decreasing rapidly from T9-T12. Discs in the thoracic spine are much thinner than in the cervical and lumbar spine. Two lamina bones join the pedicles to complete the ring. The two nerves that leave the spine at each vertebra go through the foramina, one on the left and one on the right. 2018 Jan, Shanbhag NC,Duyff RF,Groen RJM, Symptomatic Thoracic Nerve Root Herniation into an Extradural Arachnoid Cyst: Case Report and Review of the Literature. The thoracic spine has 12 vertebrae stacked on top of each other, labeled from T1 down to T12. There are three atypical vertebrae found in the thoracic region: The superior costal facets of T1 are “whole” costal facets. Ossification completes around the age of 25. Why do you suppose there are more in the horse? The ribs restrict the movement of the thoracic spine somewhat. Muscles also connect from one rib to the next. The primary characteristic of the thoracic vertebrae is the presence of costal facets. Two pedicle bones connect directly to the back of the vertebral body. Anatomy. Check for errors and try again. The thoracic spine has a relatively narrow vertebral canal, which predisposes it to spinal cord damage and neurological deficit. The muscles of the thoracic spine are arranged in layers. The section of the spinal column called the thoracic spine begins below the cervical spine (C7, neck), roughly at shoulder level and continues downward until it reaches the first level of the low back (L1, lumbar spine). These muscles run up and down over the lower ribs and thorax (the rib cage), and cross to the low back. Knowing the main parts of the thoracic spine and how these parts work is important as you learn to care for your back problem. An outward curve, as in the thoracic spine, is called kyphosis. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. The anterior longitudinal ligament runs lengthwise down the front of the vertebral bodies. T11 and T12 are atypical in that they contain a single pair, “whole,” costal facet that articulate with the 11 and 12 ribs, respectively. This begins at the thoracolumbar junction and proceeds in the cranial and caudal directions. A bony knob projects out at the point where the two lamina bones join together at the back of the spine. Along with the sternum and ribs, the thoracic spine forms part of the thoracic cage. Each thoracic spinal nerve is named for the vertebra above it. The ribs restrict the movement of the thoracic spine somewhat. The increased size helps balance and support the larger muscles that connect to the lower parts of the spine. The alignment of the facet joints of the thoracic spine allows freedom of movement as you twist back and forth or lean side to side. Typical vertebrae consist of a vertebral body, a vertebral arch, as well as seven processes. A facet joint sits in back of the foramen. Most thoracic vertebrae have similar features with the exception of some atypical ones.