Final answer:
Cervical vertebrae feature a small body, bifid spinous process, U-shaped transverse processes with a transverse foramen for nerve passage, and flattened articular processes. The atlas (C1) and axis (C2) have unique features such as the absence of a body or spinous process in the atlas and the presence of the dens in the axis.
Step-by-step explanation:
General Features of Cervical Vertebrae
The cervical vertebrae are the bones that make up the neck region of the spinal column. Specific features characterize these vertebrae. Each typical cervical vertebra, like C4 or C5, has a small body compared to vertebrae in other regions, which correlates with the lesser amount of body weight they support. They also commonly have a bifid spinous process, which is Y-shaped. This bifid design is seen in vertebrae C3-C6, with shorter spinouses, while C7 features a much longer spinous process that is easy to feel at the base of the neck.
The transverse processes of cervical vertebrae are U-shaped and house an important structure called the transverse foramen. The cervical spinal nerves pass through these curved processes, and an essential artery runs through the transverse foramina to supply blood to the brain. Moreover, the articular processes of these vertebrae are flattened and oriented to face upward or downward, which influences the movement and articulation between adjacent vertebrae.
Two exceptions to the typical structure are the C1 and C2 vertebrae, known as the atlas and axis, respectively. The atlas (C1) is unique because it does not have a body or spinous process, but instead forms a ring with anterior and posterior arches. Its transverse processes are elongated for articulation with the occipital condyles at the skull's base. The axis (C2) has a distinctive feature called the dens that projects upward for articulation with the atlas.
In comparison to cervical vertebrae, the thoracic vertebrae have larger bodies and long, downward-angling spinous processes that overlap with the next inferior vertebra. The orientation of the superior and inferior articular processes plays a significant role in the range of movements available in the thoracic region of the spine.