Figure 1-19.—Cervical vertebrae

Lumbar.—There are five lumbar vertebrae. Located in the small of the back, these vertebrae are the larger and stronger segments of the vertebral column. Sacrum.—The sacrum is the triangular bone immediately below the lumbar vertebrae. It is composed of five separate vertebrae that gradually fuse together between 18 and 30 years of age. The sacrum is connected on each side with the hip bone and with the coccyx to form the posterior wall of the pelvis. THORAX.—This cone-shaped bony cage is about as wide as it is deep (fig. 1-20). The thorax is formed by 12 ribs on each side and articulates posteriorly with the thoracic vertebrae. The first set of ribs are attached to the manubrium, a flat irregular bone atop the sternum. The first seven pairs of ribs are called true ribs. The remaining five pairs are called false ribs. They are called false ribs because their cartilages do not reach the sternum directly. The eighth, ninth, and tenth ribs are united by their cartilages and joined to the rib above. The last two rib pairs, also known as floating ribs , have no cartilaginous attachments to the sternum. The sternum is an elongated flat bone, forming the middle portion of the upper half of the chest wall in front. The xiphoid process, located at the inferior aspect of the sternum, serves as a landmark in the administration of cardiopulmonary resuscitation. 1-11 HM3F0118 SPINOUS PROCESS LAMINA TRANSVERSE PROCESS SUPERIOR ARTICULAR PROCESS PEDICLE BODY PEDICLE BODY INTERVERTEBRAL FORAMEN INFERIOR ARTICULATING PROCESS SUPERIOR ARTICULATING PROCESS TRANSVERSE PROCESS FACET FOR TUBERCLE OF RIB SPINOUS PROCESS A B Figure 1-18.—Typical vertebra: A. Lateral view of a typical vertebra; B. Superior view of a typical thoracic vertebra. INTERVERTEBRAL FORAMEN 3RD TO 7TH CERVICAL VERTEBRAE HM3F0119 AXIS ATLAS Figure 1-19.—Cervical vertebrae.