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