What is a Vertebral Column?

The vertebral column (also known as the backbone or spine) is a tall, thin bone that runs from the base of the spine to the pelvis and is located dorsally. It protects the spinal cord and serves as a vital connection point for a variety of muscle groups.

The human spine has 33 vertebrae that are divided into five regions based on the curvature of the spine: cervical, thoracic, lumbar, sacrum, and coccyx. The sacrum and coccyx vertebrae are fused, but intervertebral discs distinguish the cervical, thoracic, and lumbar vertebrae.

"A vertebral column"

Characteristics of the Vertebral Column

Vertebrae are assigned an alphanumeric descriptor, which begins with a letter originating from the region in which they are found and ends with a digit that rises as the region progresses. The most superior cervical vertebra is designated C1, while the most inferior is designated C7, followed by the T1 vertebrae of the thoracic region.

The vertebral column has multiple curves that correspond to the various regions of the column when viewed laterally. The cervical, thoracic, lumbar, and pelvic regions are the four parts of the spine.

  • The cervical curve is the smallest of all the spinal curves, covering the region between vertebrae C1 and T2.
  • The thoracic curve encompasses the region between T2 and T12.
  • Owing to variations in the pelvic structure, the lumbar curve covers the area between vertebrae T12 and L5. The lumbar curve is more prominent in females than in males.
  • The Sacro vertebral articulation marks the start of the sacral curve, which ends at the coccyx.

Since these are the only curves present throughout fetal development, the thoracic and sacral curves are referred to as primary curves. The cervical and lumbar curves grow after birth, with the former occurring when the child maintains an upright posture and the latter occurring when the child starts to walk.

Parts of the Vertebral column

An anterior section, also known as the vertebral body, and a posterior segment, also known as the vertebral (neural) arch, make up a vertebra.
When the vertebrae are articulated together, they form a solid but flexible structure that encloses the vertebral foramen, or opening, through which the spinal cord passes. It also serves as a foundation for a variety of muscle attachments and joint articulations with other bones.

The arrangement of the individual vertebrae generates the structure's strength and flexibility. The configuration of a vertebra, which is made up of bone and cartilage, varies depending on where it is in the body, but there are some similar features for the vertebra in the upper region.

"Superior view of a vertebra"

In the upper part of the spine, a typical vertebra has two regions:

  • The point of articulation between the vertebrae is known as the anterior vertebral body.
  • The neural arch, or posterior vertebral arch, encloses the spinal cord.

The vertebral arch is made up of two small, thick processes called pediments that reach posteriorly from the lateral sides of the vertebral body and join with the laminae at the midline.

Vertebral Processes

Seven processes project from a typical vertebra.

The joint between the pedicles and laminae gives rise to four articular processes, two of which point superiorly and two of which point inferiorly. They connect with the adjacent vertebrae's zygapophyses, a socket for the articular processes, to stabilize the spine and allow for a limited degree of articulation.

From the middle of the vertebral arch, a single spinous process extends backward and downwards, serving as the main attachment point for back muscles and ligaments.

The two transverse processes protrude laterally from the pedicle-lamina junction and act as attachment points for back muscles and ligaments. In combination with the vertebral body, the transverse processes articulate with the ribs.

Based on the five different curvatures of the spine, the vertebrae that make up the spinal column can be divided into five regions. The cervical, thoracic, and lumbar regions of the spinal column contain individually jointed vertebrae. The sacrum and coccyx, or tailbone, are two lower regions made up of fused vertebrae.

Upper Vertebrae

The most superior area of the spine is the cervical region, which includes seven small vertebrae. The cervical region's primary role is to aid in the attachment of the skull to the spine, to protect the spinal cord over the exposed neck and shoulder region, and to support the body.

The thoracic vertebrae are found beneath the cervical vertebrae. They are larger than the cervical vertebrae and grow in size on moving down in the spine.

The five lumbar vertebrae are the largest vertebral bones, and upon moving inferiorly, they grow in size. The lumbar vertebrae play an important role in body support and locomotion.

Lower Vertebrae

The sacral region's five vertebrae are distinct during childhood. The sacrum is formed as the five bones join together in adulthood, but it is still divided into S1–S5 regions based on the formation of the initial individual bones. The sacrum supports and protects the body's organs in the pelvis and lower back.

The coccyx, or tailbone, is the last segment of the spine. The coccyx, like the sacrum, is made up of several fused vertebrae.

"A section of the vertebral column representing multiple vertebrae"

It is inaccurate to think of the coccyx as a vestigial structure since it is a key attachment point for many muscles and ligaments and plays an essential role in supporting the body when seated. As the alternative name of coccyx implies, it forms the basis of a tail that has been lost in humans.

Curvatures of the Vertebral Column

The adult vertebral column does not form a straight line along its length but instead has four curves. The resilience, durability, and ability to withstand the shock of the vertebral column are all improved by these curves. As the load on the spine is increased, such as when wearing a heavy backpack, the curvatures deepen (become more curved) to support the additional weight. When the weight is removed, they come back to life. Main and secondary curvatures are the two types of adult curvatures. Primary curves are preserved from fetal development, while secondary curves emerge after birth.

The body is flexed anteriorly into the fetal position during development, giving the entire vertebral column a single concave anterior curvature. The thoracic curve, which is formed by the thoracic vertebrae, and the sacrococcygeal curve, which is formed by the sacrum and coccyx, both maintain this fetal curvature in the adult. Since these curves are preserved from the initial fetal curvature of the vertebral column, each of them is referred to as a primary curve.

As the infant learns to sit, stand, and walk, a secondary curve grows progressively after birth. Secondary curves are concave in the back and run in the same direction as the initial fetal curvature. When the child continues to sit and keep his head straight, the cervical curve of the neck grows. The lumbar curve of the lower back grows as the infant learns to stand and then walk. Females have a broader lumbar curve than males do as adults.

Kyphosis (excessive posterior curvature of the thoracic region), lordosis (excessive anterior curvature of the lumbar region), and scoliosis (an abnormal, lateral curvature, along with the twisted vertebral column)are all disorders associated with the curvature of the spine.

Content and Applications  

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for

  • Bachelors in Zoology
  • Bachelors General Physiology
  • Masters of Science in Human Physiology  
  • Masters of Science in Anatomy and Physiology

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