Vertebrae

Vertebral column

• 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

How many vertebrae do we have?

• Adult: 26

• Infant: 33 separate bones– Five vertebrae fuse to form the sacrum and

four others join to become the coccyx

Components of vertebral column

• Cervical vertebrae

• Thoracic vertebrae

• Lumbar vertebrae

• Sacrum

• coccyx

Curvatures of vertebral columnfig 7.34

• 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)

3 parts of Vertebra• 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

Cervical Vertebrae• 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

Atlas

Axis

Distinctions of Cervical

• 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)

Thoracic Vertebrae• 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

Thoracic

• 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

Lumbar • 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

Lumbar

• Short spinous processes are nearly horizontal: provide surface area for muscle attachment of lower back muscles

• Smaller vertebral foramen

• Injuries: Compression, Slip Disk

Sacral Vertebraefig 7.39

• 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

http://anatome.ncl.ac.uk/tutorials/columneasy/images/page5a.jpg

Coccygeal

• Originates as 4 vertebra, fuses as 1 bone

• Fusion of time varies

• Attached by ligaments to margins of the sacral hiatus