Scoliosis is an abnormal, lateral curvature, accompanied by twisting of the vertebral column. This causes in an anterior tilt of the pelvis and a pronounced enhancement of the lumbar curve. The accumulation of body weight in the abdominal region results an anterior shift in the line of gravity that carries the weight of the body. Lordosis, or swayback, is an excessive anterior curvature of the lumbar region and is most commonly associated with obesity or late pregnancy. This can develop when osteoporosis causes weakening and erosion of the anterior portions of the upper thoracic vertebrae, resulting in their gradual collapse ( ). Kyphosis, also referred to as humpback or hunchback, is an excessive posterior curvature of the thoracic region. In adults, the lumbar curve is generally deeper in females.ĭisorders associated with the curvature of the spine include kyphosis (an excessive posterior curvature of the thoracic region), lordosis (an excessive anterior curvature of the lumbar region), and scoliosis (an abnormal, lateral curvature, accompanied by twisting of the vertebral column).ĭevelopmental anomalies, pathological changes, or obesity can enhance the normal vertebral column curves, resulting in the development of abnormal or excessive curvatures ( ). Later, as the child begins to stand and then to walk, the lumbar curve of the lower back develops. The cervical curve of the neck region develops as the infant begins to hold their head upright when sitting. Secondary curves are concave posteriorly, opposite in direction to the original fetal curvature. Each of these is thus called a primary curve because they are retained from the original fetal curvature of the vertebral column.Ī secondary curve develops gradually after birth as the child learns to sit upright, stand, and walk. In the adult, this fetal curvature is retained in two regions of the vertebral column as the thoracic curve, which involves the thoracic vertebrae, and the sacrococcygeal curve, formed by the sacrum and coccyx. Primary curves are retained from the original fetal curvature, while secondary curvatures develop after birth.ĭuring fetal development, the body is flexed anteriorly into the fetal position, giving the entire vertebral column a single curvature that is concave anteriorly. The four adult curvatures are classified as either primary or secondary curvatures. They then spring back when the weight is removed. When the load on the spine is increased, by carrying a heavy backpack for example, the curvatures increase in depth (become more curved) to accommodate the extra weight. These curves increase the vertebral column’s strength, flexibility, and ability to absorb shock. The adult vertebral column does not form a straight line, but instead has four curvatures along its length (see ). In a full-grown giraffe, each cervical vertebra is 11 inches tall. This means that there are large variations in the size of cervical vertebrae, ranging from the very small cervical vertebrae of a shrew to the greatly elongated vertebrae in the neck of a giraffe. However, the sacral and coccygeal fusions do not start until age 20 and are not completed until middle age.Īn interesting anatomical fact is that almost all mammals have seven cervical vertebrae, regardless of body size. Similarly, the coccyx, or tailbone, results from the fusion of four small coccygeal vertebrae. The single sacrum, which is also part of the pelvis, is formed by the fusion of five sacral vertebrae. The lower back contains the L1–L5 lumbar vertebrae. Below these are the 12 thoracic vertebrae, designated T1–T12. Inferiorly, C1 articulates with the C2 vertebra, and so on. Superiorly, the C1 vertebra articulates (forms a joint) with the occipital condyles of the skull. In the neck, there are seven cervical vertebrae, each designated with the letter “C” followed by its number. The vertebral column is subdivided into five regions, with the vertebrae in each area named for that region and numbered in descending order.
#Anterior vertebral arch plus#
The vertebral column originally develops as a series of 33 vertebrae, but this number is eventually reduced to 24 vertebrae, plus the sacrum and coccyx.
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