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