On April 3, 2011 my wife, Virginia took a spill from her horse Woogie, going over his head and landing on her head and right shoulder. A CT scan revealed four fractured ribs and a fracture of the right transverse process of her first thoracic vertebrae.

Fractures to the spinal vertebrae are of grave concern, obviously because any damage or swelling of the spinal column can put a person at risk for paralysis, chronic pain or disability. After ascertaining that there was no risk of spinal column damage, the first question that we had was,

"She broke what, now?"

The transverse processes, one on each side of each vertebae, project one at either side from the point where the lamina joins the pedicle, between the superior and inferior articular processes. They serve for the attachment of muscles and ligaments.

The human spine is comprised of 33 vertebrae; there are seven in the cervical region, twelve in the thoracic, five in the lumbar, five in the sacral, and four in the coccygeal. A typical vertebra consists of two essential parts: an anterior segment or the body, and a posterior part or the vertebral neural arch. This vertebral arch consists of a pair of pedicles and a pair of lamiae, and supports seven processes: four articular, two transverse, and one spinous.

In the cervical vertebrae, the transverse processes are each pierced by the foramen transversarium, which, in the upper six cervical vertebae, gives passage to the vertebral artery and vein and a plexus of sympathetic nerves. Each process consists of an anterior and a posterior part. The anterior portion is the homologue of the rib in the thoracic region, and is therefore named the costal process or costal element: it arises from the side of the body, is directed lateralward in front of the foramen, and ends in a tubercle, the anterior tubercle. The posterior part, the true transverse process, springs from the vertebral arch behind the foramen, and is directed forward and lateralward; it ends in a flattened vertical tubercle, the posterior tubercle. These two parts are joined, outside the foramen, by a bar of bone which exhibits a deep sulcus on its upper surface for the passage of the corresponding spinal nerve.

In the thoracic vertebrae, the transverse processes arise from the arch behind the superior articular processes and pedicles; they are thick, strong, and of considerable length, directed obliquely backward and lateralward, and each ends in a clubbed extremity, on the front of which is a small, concave surface, for articulation with the tubercle of a rib.

In the lumbar vertebrae, the transverse processes are long, slender, and horizontal in the upper three lumbar vertebræ; they incline a little upward in the lower two. In the upper three vertebræ they arise from the junctions of the pedicles and laminæ, but in the lower two they are set farther forward and spring from the pedicles and posterior parts of the bodies. They are situated in front of the articular processes instead of behind them as in the thoracic vertebræ, and are homologous with the ribs. Of the three tubercles noticed in connection with the transverse processes of the lower thoracic vertebræ, the superior one is connected in the lumbar region with the back part of the superior articular process, and is named the mammillary process; the inferior is situated at the back part of the base of the transverse process, and is called the accessory process.

The sacral and coccygeal vertebae consist at an early period of life of nine separate segments which are united in the adult, so as to form two bones. On the dorsal side of the sacrum, is the posterior sacral foramina. On its lateral side, are a series of tubercles, which represent the transverse processes of the sacral vertebræ, and form the lateral crests of the sacrum. The transverse tubercles of the first sacral vertebra are large and very distinct; they, together with the transverse tubercles of the second vertebra, give attachment to the horizontal parts of the posterior sacroiliac ligaments; those of the third vertebra give attachment to the oblique fasciculi of the posterior sacroiliac ligaments; and those of the fourth and fifth to the sacrotuberous ligaments. On base of the sacrum a structure called an ala. The posterior fourth of the ala represents the transverse processes. The coccyx is usually formed of four rudimentary bones. In each of the first three segments may be traced rudimentary transverse processes.

The transverse processes can be fractured by rotational injuries. Seatbelt injuries, falls from a height such as from a horse or bike and sport injuries such as from rugby and American football are the most common. Rib and clavicle fractures can often accompany thoracic transverse process. Non-detached fractures of the transverse processes in cervical and thoracic vertebrae can be considered as clinically insignificant and do not require treatment. Unrestricted movement resulted in satisfying functional, anatomic, and neurologic outcomes without associated adverse events. Transverse process fractures are predominantly treated with gradual increase in motion, with or without bracing, based on comfort level. The transverse processes in lumbar vertebrae can be also fractured by rotational injuries and in itself is considered a relatively mirror injury, but the force required to break these processes are very often accompanied by more serious organ damage.

Extensively excerpted from Grey’s Anatomy.

Additional references:

http://journals.lww.com/spinejournal/Abstract/2010/09010/Isolated_Transverse_Process_Fractures_of_the.26.aspx

http://www.injuryjournal.com/article/S0020-1383(00)00111-X/abstract

http://orthoinfo.aaos.org/topic.cfm?topic=a00368

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Lizardinlaw has been helping me out in searching for more information. She cited the following:

It talks about the combination of fractured ribs with fracture of parts of the vertebra as being less stable. The transverse process (attaches) the "superior costotransverse ligament" which helps to stabilize the rib (from John Connolly's Fractures and Dislocations: Closed Management.)

"Remember, it's not just bones that brake: the ligaments and muscles are attached to the bones and they get torn and banged up. Find an Atlas of Human Anatomy by Frank Netter and look at the spine, ribs, ligaments and then the layers of back muscles."

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