• Extends from skull to pelvis
• Consists of many vertebrae separated by cartilaginous intervertebral disks that are connected by ligaments
• Forms central axis of the skeleton

• Supports the head and the trunk of the body
• Flexible to permit movements
• Protects the spinal cord

• Adult: 26
• Infant: 33 separate bones
– Five vertebrae fuse to form the sacrum and four others join to become the coccyx

• Cervical vertebrae
• Thoracic vertebrae
• Lumbar vertebrae
• Sacrum
• coccyx

• Names correspond to the regions in which they occur
• 1. thoracic concave anteriorly (primary
• 2. pelvic curves)
• 3. cervical convex anteriorly (2ndary
• 4. lumbar curves)

• Body: (centrum)
– Transfers weight along the axis; separated by intervertebral discs
• Arch: surrounds vertebra foramen
• Articular process:
– Intervertebral foramina: gaps b/t ea vertebra; permits passage of nerves to or from spinal cord

• Comprise the bony axis of the neck
• Smallest of the vertebrae, but tissue are denser than those in any other region of column
• Allows for 180 degree range of motion
• Atlas : (C1) holds up head
– Practically no body or spine
– Pivots around the dens of axis
• Axis : (C2) during development fuses with atlas

• Atlas : (C1) holds up head
– Practically no body or spine
– Pivots around the dens of axis
• Axis : (C2) during development fuses with atlas

• Transverse processes of cervical are DISTINCT b/c of transverse foramina
– Passageways for arteries leading to the brain
• Spinous processes:
Uniquely forked (bifid): provide attachment for muscles
• Vertebra prominens: longer and protrudes beyond other cervical (can be felt thru skin)

• Total of 12
• Larger than cervical
• Long pointed spinous process slopes downward
• Bear increasing loads of body weight due to the increase in the body size of the vertebra

• Demi facets: on side of body to articulate with ribs
• Injury: compression-dislocation fractures of vertebrae occur b/t throacic and lumbar due to heavy weight bearing load

• Total of 5 in small of back
• Supports more weight b/c of larger and stronger bodies
• Transverse processes project posteriorly at sharp angles
• Large Bodies

• Short spinous processes are nearly horizontal: provide surface area for muscle attachment of lower back muscles
• Smaller vertebral foramen
• Injuries: Compression, Slip Disk

• Originates as 5 vertebrae
• Complete fusion by age 25 (18-30)

• Dorsal sacral foramina: blood vessels pass thru
• sacral promontory: first sacral vertebra
• Sacral canal: opening
• Sacral hiatus: opening at end of sacrum
• Sacral foramina: 4 pairs that provide passageways for blood vessels and nerves

• Originates as 4 vertebra, fuses as 1 bone
• Fusion of time varies
• Attached by ligaments to margins of the sacral hiatus