Backbone is another name that the vertebral column is used to identify. A flexible column that runs from the neck to the tail of the vertebrate body is the vertebral column. The primary characteristic used to distinguish vertebrates from other chordates is usually the presence of a vertebral column.
A notochord is usually formed by chordates; this notochord can be identified only during embryonic development in vertebrates. Later, it grows into the vertebral column. In addition, the vertebral column consists of a series of vertebrae grouped as cervical, thoracic, lumbar, sacral, and coccygeal vertebrae and is a bony structure. Humans have a backbone of 33 vertebrae. In addition, housing the spinal canal is the main feature of the vertebral column or backbone; the spinal cord extends from head to tail within this canal.
It also provides the spinal cord with protection and provides sites for the nerves to emerge from the spinal cord. The spinal cord is basically one of the two components of the central nervous system , while the brain is the second component. Here, the backbone provides muscles such as pectoral and pelvic girdles and many muscles for attachment sites.
In addition, when standing and walking, the backbone transmits body weight into the pelvis. The key distinction between the backbone and the spine is that the more informal term for the vertebral column is the backbone, whereas the more formal term is the spine. Spinal Cord. Consisting of bundles of nerve fibres. The backbone consists of bones known as vertebrae.
The spinal cord serves as a means of contact between the body and the brain. The backbone helps to provide structural assistance as well as carry the weight of the body. It is also charged with spinal cord security.
Usually, the brain sends motor messages through the spinal cord to the limbs in order to control movements. Moreover, it contains many reflex arcs, which can control reflexes independently from the brain, resulting in unconscious muscular movements.
Figure 1: Spinal Cord — Sectional Anatomy. Furthermore, the spinal cord is made up of both grey matter and white matter. Additionally, the three regions of the spinal cord are the cervical, thoracic, and lumbar region. On each side of the spinal cord, two consecutive nerve roots of spinal nerves emerge. They include eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves.
Vertebrae are the series of individual bony structures that form the vertebral column. Each vertebra in the column is separated by an intervertebral disk, which forms a fibrocartilaginous joint, allowing slight movement of vertebrae, acting as a ligament to hold the vertebrae together, and functioning as a shock absorber for the spine.
Generally, 33 vertebrae incorporate to form the vertebral column. They include 24 presacral vertebrae 7 cervical , 12 thoracic , and 5 lumbar followed by the sacrum 5 fused sacral vertebrae and the coccyx 4 frequently fused coccygeal vertebrae.
Figure 2: Vertebrae — Anatomy. Although the size, shape, and the function of different types of vertebrae differ with the region, all follow a similar structural pattern. That means a typical vertebra will consist of a body, a vertebral arch, and seven processes. The main function of the body of the vertebra is to support the body weight of animals with upright posture.
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. The spinal cord is about 18 inches long and is the thickness of your thumb.
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