Page 340 - Clinical Anatomy

ECA5 7/18/06 6:51 PM Page 325

The vertebral column 325

Fig. 228◊A‘typical’ thoracic vertebra.

intervertebral foramen. The arch bears a posterior spine, lateral transverse
processes and upper and lower articular facets.
The intervertebral foramina transmit the segmental spinal nerves as
follows: C1–7 pass over the superior aspect of their corresponding cervical
vertebrae, C8 passes through the foramen between C7 and T1, and all sub-
sequent nerves pass between the vertebra of their own number and the one
below.
Now to consider the individual vertebrae in turn.

The cervical vertebrae (7)
These are readily identified by the foramen transversarium perforating the
transverse processes. This foramen transmits the vertebral artery, the vein,
and sympathetic nerve fibres. The spines are small and bifid (except C1
and C7 which are single) and the articular facets are relatively horizontal
(Fig. 229).
The atlas (C1) (Fig. 230) has no body. Its upper surface bears a superior
articular facet on a thick lateral mass on each side which articulates with the
occipital condyles of the skull.