## **Core Concept**
The vertebral column has four main curvatures when viewed from the side: cervical, thoracic, lumbar, and sacral. Primary curves are present in the thoracic and sacral regions, with concavity forwards. Secondary curves develop in the cervical and lumbar regions, with concavity backwards.

## **Why the Correct Answer is Right**
The cervical and lumbar parts of the vertebral canal exhibit secondary curves. These curves are characterized by their concavity being directed backwards. This anatomical feature is crucial for understanding spinal anatomy and its clinical implications.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option does not correspond to the cervical or lumbar regions; hence, it does not exhibit a secondary curve with concavity backwards.
* **Option B:** Similarly, this option does not align with the regions known for secondary curves.
* **Option D:** This option also does not match the cervical or lumbar regions.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the vertebral column's curvatures are not just anatomical features but also have clinical significance, especially in conditions like kyphosis (exaggeration of thoracic curvature) and lordosis (exaggeration of cervical or lumbar curvature).

## **Correct Answer:** . Cervical and Lumbar.