What type of bone is vertebrae

The second vertebra C2 is the peg-shaped axis, which has a projection called the odontoid, that the atlas pivots around. Thoracic mid back - the main function of the thoracic spine is to hold the rib cage and protect the heart and lungs.

The twelve thoracic vertebrae are numbered T1 to T The range of motion in the thoracic spine is limited. Lumbar low back - the main function of the lumbar spine is to bear the weight of the body. The five lumbar vertebrae are numbered L1 to L5. These vertebrae are much larger in size to absorb the stress of lifting and carrying heavy objects.

Sacrum - the main function of the sacrum is to connect the spine to the hip bones iliac. There are five sacral vertebrae, which are fused together. Together with the iliac bones, they form a ring called the pelvic girdle. Coccyx region - the four fused bones of the coccyx or tailbone provide attachment for ligaments and muscles of the pelvic floor.

While vertebrae have unique regional features, every vertebra has three functional parts Fig. Each vertebra in your spine is separated and cushioned by an intervertebral disc, which keeps the bones from rubbing together. Discs are designed like a radial car tire.

The outer ring, called the annulus, has crisscrossing fibrous bands, much like a tire tread. These bands attach between the bodies of each vertebra. Inside the disc is a gel-filled center called the nucleus, much like a tire tube Fig.

Discs function like coiled springs. The crisscrossing fibers of the annulus pull the vertebral bones together against the elastic resistance of the gel-filled nucleus. The nucleus acts like a ball bearing when you move, allowing the vertebral bodies to roll over the incompressible gel.

The gel-filled nucleus contains mostly fluid. This fluid is absorbed during the night as you lie down and is pushed out during the day as you move upright. With age, our discs increasingly lose the ability to reabsorb fluid and become brittle and flatter; this is why we get shorter as we grow older.

Also diseases, such as osteoarthritis and osteoporosis, cause bone spurs osteophytes to grow. Injury and strain can cause discs to bulge or herniate, a condition in which the nucleus is pushed out through the annulus to compress the nerve roots causing back pain. On the back of each vertebra are bony projections that form the vertebral arch.

The arch is made of two supporting pedicles and two laminae Fig. The hollow spinal canal contains the spinal cord, fat, ligaments, and blood vessels. Under each pedicle, a pair of spinal nerves exits the spinal cord and pass through the intervertebral foramen to branch out to your body. Surgeons often remove the lamina of the vertebral arch laminectomy to access the spinal cord and nerves to treat stenosis, tumors, or herniated discs.

Seven processes arise from the vertebral arch: the spinous process, two transverse processes, two superior facets, and two inferior facets. The facet joints of the spine allow back motion. Each vertebra has four facet joints, one pair that connects to the vertebra above superior facets and one pair that connects to the vertebra below inferior facets Fig. The ligaments are strong fibrous bands that hold the vertebrae together, stabilize the spine, and protect the discs.

The three major ligaments of the spine are the ligamentum flavum, anterior longitudinal ligament ALL , and posterior longitudinal ligament PLL Fig.

The ALL and PLL are continuous bands that run from the top to the bottom of the spinal column along the vertebral bodies. They prevent excessive movement of the vertebral bones.

The ligamentum flavum attaches between the lamina of each vertebra. They consist primarily of spongy bone, which is covered by a thin layer of compact bone. Short bones include the bones of the wrist and ankle.

Flat bones are thin, flattened, and usually curved. Most of the bones of the cranium are flat bones. Bones that are not in any of the above three categories are classified as irregular bones. X-rays of the hand , hip , knee , and ankle. Stony Brook University School of Medicine. The Body Online. An Overview of the Skeletal System.

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Learn Site. So, what are the different types of bones? How are they categorized? There are five types of bones in the skeleton: flat, long, short, irregular, and sesamoid. Flat Bones Protect Internal Organs There are flat bones in the skull occipital, parietal, frontal, nasal, lacrimal, and vomer , the thoracic cage sternum and ribs , and the pelvis ilium, ischium, and pubis.