![]() The spinous process of cervical vertebrae increases as the spinal column descends. Another feature unique to the cervical vertebrae is the bifid spinous process (See “physiologic variants” section), which may serve to increase surface area for muscle attachment. This is true of all cervical vertebrae except C7, whose transverse foramina contain only accessory veins. ![]() These transverse foramina encircle the vertebral arteries and veins. The most notable distinction is the presence of one foramen, in each transverse process. Typical cervical vertebrae have several features distinct from those typical of thoracic or lumbar vertebrae. Lastly, the two transverse processes project laterally from the vertebral arch in a symmetrical fashion. The spinous process projects posteriorly, and often inferiorly from the vertebral arch and may overlap the inferior vertebrae to various degrees, depending on the region of the spine. These maintain vertebral alignment, control the range of motion, and are weight-bearing in certain positions. The point at which superior and articular facets meet is known as a facet, or zygapophyseal, joint. A typical vertebra also contains four articular processes, two superior and two inferior, which contact the inferior and superior articular processes of adjacent vertebrae, respectively. The arch consists of bilateral pedicles, cylindrical processes of bone that connect the arch to the body, and bilateral lamina, flat, bone segments form most of the arch, connecting the transverse and spinous processes. The arch, along with the posterior aspect of the body, forms the vertebral (spinal) canal, which contains the spinal cord. The vertebral body consists of trabecular bone, which contains the red marrow, surrounded by a thin external layer of compact bone. Vertebral bodies increase in size from superior to inferior. ![]() The body bears the majority of the force placed on the vertebra. Typical vertebrae consist of a vertebral body, a vertebral arch, as well as seven processes. While all vertebrae share most morphologic features, there are several notable features in the cervical region. The cervical vertebrae, as a group, produce a lordotic curve. The intervertebral discs, along with the laminae and the articular processes of adjacent vertebrae, create a space through which spinal nerves exit. The cervical region contains seven vertebrae, denoted C1-C7, which are the smallest of the vertebral column. The intervertebral discs are responsible for this mobility without sacrificing the supportive strength of the vertebral column. The spine has several major roles in the body that include: protection of the spinal cord and branching spinal nerves, support for thorax and abdomen, and allows for flexibility and mobility of the body. It extends from the skull to the coccyx and includes the cervical, thoracic, lumbar and sacral regions. This knowledge hopefully helps prevent the type of wrong-level instrumentation that we performed.īifid cervicothoracic frequency monofid morphology posterior cervical surgery spinous process wrong-level surgery.Vertebrae, along with intervertebral discs, compose the vertebral column, or spine. A truly bifid C7 spinous process occurs 0.3% of the time and therefore is not a reliable landmark for choosing fusion levels. C7 spinous process was monofid in 99.2% of cases, partially bifid in 0.5% of cases, and bifid in 0.3% of cases. The spinous processes were classified into three categories: "bifid," "partially bifid," and "monofid." C6 spinous process was monofid in 47.9% of cases, partially bifid in 4.2% of cases, and bifid in 47.9% of cases. Computed tomography axial images of C6, C7, and T1 from 516 patients were evaluated. We therefore sought to determine the frequency of bifid cervicothoracic spinous processes. Relying on the C7 morphology, however, we initially instrumented the wrong levels in a case where the patient had a bifid C7 spinous process. In such cases, we usually place a marker at the top of the incision and also rely on the size and monofid shape of the C7 spinous process. For posterior cervical surgery, if the operation only involves the lower cervical area, counting from C2 is impractical and the level may not be visible on X-rays.
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