Page 269 - Fundamentals of anatomy physiology

256 Unit 2 Support and Movement
Figure 7–19 The Cervical Vertebrae. ATLAS: Plates 20b; 21a–e

C1 Vertebral Spinous process
arch
C2 Lamina
Vertebral Superior articular
foramen
process
Pedicle
C3
7 C4 Vertebral body
C5
Spinous C6 Transverse Transverse Superior
process of process foramen articular
C7
vertebra Costal process facet
prominens a A lateral view of the
cervical vertebrae, C1–C7.
b A superior view of a representative cervical
vertebra showing characteristics of C3–C6.
Notice the typical features listed in Table 7–1.

Superior articular Anterior Dens of
process arch axis

Transverse process Transverse
ligament
Inferior articular
process Location of Atlas
transverse (C1)
Spinous foramen
process Posterior
arch
Bifid tip of
spinous Axis (C2)
process

Inferior articular Vertebral
facet body

c A lateral view of the same vertebra as in b. d The atlas (C1) and axis (C2) in
posterolateral view.

the body. The diameter of the spinal cord decreases as you pro- notch (Figure 7–19b). A notched spinous process is said to be
ceed caudally along the vertebral canal, and so does the diam- bifid (BI.-fid).
eter of the vertebral arch. However, cervical vertebrae support
only the weight of the head, so the vertebral body can be rela- Laterally, the transverse processes are fused to the costal
tively small and light. As you continue toward the sacrum, the processes, which originate near the ventrolateral portion of
loading increases and the vertebral bodies gradually enlarge.
the vertebral body. The costal and transverse processes encircle
In a typical cervical vertebra, the superior surface of the prominent, round transverse foramina. These passageways
body is concave from side to side, and it slopes, with the an-
terior edge inferior to the posterior edge (Figure 7–19c). Ver- protect the vertebral arteries and vertebral veins. These important
tebra C1 has no spinous process. The spinous processes of the
other cervical vertebrae are relatively stumpy, generally shorter blood vessels service the brain.
than the diameter of the vertebral foramen. In the case of ver-
tebrae C2–C6, the tip of each spinous process has a prominent The preceding description is adequate for identifying the
cervical vertebrae C3–C6. The first two cervical vertebrae are
unique, and the seventh is modified. We will describe these

vertebrae shortly. The interlocking bodies of articulated C3–
C7 permit more flexibility than do those of other regions.