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Hyoid bone. U-shaped bone located just above the larynx and below the mandible Suspended from the styloid processes of the temporal bone Only bone in the body that articulates with no other bones. Vertebral column. Forms the flexible longitudinal axis of the skeleton
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Hyoid bone • U-shaped bone located just above the larynx and below the mandible • Suspended from the styloid processes of the temporal bone • Only bone in the body that articulates with no other bones
Vertebral column • Forms the flexible longitudinal axis of the skeleton • Consists of 24 vertebrae plus the sacrum and coccyx • Segments of the vertebral column: • Cervical vertebrae, 7 • Thoracic vertebrae, 12 • Lumbar vertebrae, 5 • Sacrum—in adult, results from fusion of five separate vertebrae • Coccyx—in adult, results from fusion of four or five separate vertebrae
Vertebral column • Characteristics of the vertebrae • All vertebrae, except the first, have a flat, rounded body anteriorly and centrally, a spinous process posteriorly, and two transverse processes laterally • All but the sacrum and coccyx have vertebral foramen • Second cervical vertebra has upward projection, the dens, to allow rotation of the head • Seventh cervical vertebra has long, blunt spinous process • Each thoracic vertebra has articular facets for the ribs
Vertebral column • Vertebral column as a whole articulates with the head, ribs, and iliac bones • Individual vertebrae articulate with each other in joints between their bodies and between their articular processes
Sternum • Dagger-shaped bone in the middle of the anterior chest wall made up of three parts: • Manubrium—the upper, handle part • Body—the middle, blade part • Xiphoid process—the blunt cartilaginous lower tip, which ossifies during adult life
Sternum • Manubrium articulates with the clavicle and first rib • Next nine ribs join the body of the sternum, either directly or indirectly, by means of the costal cartilage
Ribs • Twelve pairs of ribs, with the vertebral column and sternum, form the thorax • Each rib articulates with the body and transverse process of its corresponding thoracic vertebra • Ribs 2 through 9 articulate with the body of the vertebra above
Ribs • From its vertebral attachment, each rib curves outward, then forward and downward • Rib attachment to the sternum: • Ribs 1 through 8 join a costal cartilage that attaches it to the sternum • Costal cartilage of ribs 8 through 10 joins the cartilage of the rib above to be indirectly attached to the sternum • Ribs 11 and 12 are floating ribs, because they do not attach even indirectly to the sternum