Bifid spinous processes pronunciation7/31/2023 A slight lateral curvature is sometimes present in the upper thoracic region. Generally, the width of the spine gradually increases from the second cervical vertebra to the superior part of the sacrum and then decreases sharply. In frontal view, the vertebral column varies in width in several regions (see Fig. C, PA thoracic and lumbar spine showing severe scoliosis. B, Kyphosis, increased convexity of thoracic spine, and lordosis, increased concavity of lumbar spine. 8-2 A, Scoliosis, lateral curvature of spine. Any abnormal increase in the anterior convexity (or posterior concavity) of the lumbar or cervical curve is termed lordosis.įig. The lumbar and pelvic curves are more pronounced in females, who have a more acute angle at the lumbosacral junction.Īny abnormal increase in the anterior concavity (or posterior convexity) of the thoracic curve is termed kyphosis ( Fig. The lumbar curve develops when the child begins to walk at about 1 to 1½ years of age. The cervical curve, which is the least pronounced of the curves, develops when an infant begins to hold the head up at about 3 or 4 months of age and begins to sit alone at about 8 or 9 months of age. The cervical and lumbar curves are called secondary or compensatory curves because they develop after birth. The thoracic and pelvic curves are called primary curves because they are present at birth. The acuity of the angle in the junction of these curves varies among patients. The lumbar and pelvic curves join at an obtuse angle termed the lumbosacral angle. The cervical and thoracic curves merge smoothly. The thoracic and pelvic curves are concave anteriorly and are called kyphotic curves (see Fig. The cervical and lumbar curves, which are convex anteriorly, are called lordotic curves. When viewed posteriorly, the normal lumbar curve can correctly be referred to as “concave posteriorly.” Whether the curve is described as “convex anteriorly” or “concave posteriorly,” the curvature of the patient’s spine is the same. In this text, the vertebral curves are discussed in reference to the anatomic position and are referred to as “convex anteriorly” or “concave anteriorly.” Because physicians and surgeons evaluate the spine from the posterior aspect of the body, convex and concave terminology can be the exact opposites. The cervical, thoracic, lumbar, and pelvic curves are named for the regions they occupy. Viewed from the side, the vertebral column has four curves that arch anteriorly and posteriorly from the midcoronal plane of the body. The terminal vertebrae, also in the pelvic region, vary from three to five in number in adults and are termed the coccygeal vertebrae. The next five vertebrae, located in the pelvic region, are termed sacral vertebrae. The five vertebrae occupying the region of the loin are termed lumbar vertebrae. The succeeding 12 bones lie in the dorsal, or posterior, portion of the thorax and are called the thoracic vertebrae. The superiormost seven vertebrae occupy the region of the neck and are termed cervical vertebrae. These bones are divided into five groups and named according to the region they occupy ( Fig. In early life, the vertebral column usually consists of 33 small, irregularly shaped bones. The vertebral column is held together by ligaments, and it is jointed and curved so that it has considerable flexibility and resilience. Disks of fibrocartilage are interposed between the vertebrae and act as cushions. The vertebral column is composed of small segments of bone called vertebrae. This articulation supports the vertebral column and transmits the weight of the trunk through the hip joints and to the lower limbs. The vertebral column articulates with each hip bone at the sacroiliac joints. The sternum articulates with the shoulder girdle. The upper limbs are supported indirectly via the ribs, which articulate with the sternum. The vertebral column has many functions: It encloses and protects the spinal cord, acts as a support for the trunk, supports the skull superiorly, and provides for attachment for the deep muscles of the back and the ribs laterally. The vertebral column, or spine, forms the central axis of the skeleton and is centered in the midsagittal plane of the posterior part of the trunk.
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