The spine curvatures
We're happy to share with you our fourth episode of our “Spine Anatomy Fundamentals” series! In this episode, we'll be focusing on “the spine curvatures”.
Appearance of the spine
The normal spine appears rectilinear in frontal view (front view) and curved in sagittal view (profile view).
4 natural curvatures
- Cervical lordosis: natural forward curvature of the cervical (neck) region of the spine.
- Thoracic kyphosis: backward curvature is located in the thoracic region (middle of the back).
- Lumbar lordosis: natural forward curvature in the lumbar region (lower back).
- Sacrococcygeal kyphosis: Backward curvature of the spine at the level of the sacral vertebrae and coccyx.
At birth, primary curvatures as the thoracic and sacrococcygeal kyphosis are already present.
Cervical lordosis is acquired when the child raises its head while crawling or sitting, permitting to maintain neck and head balance.
Lumbar lordosis is acquired when the child stands up to begin bipedal walking, permitting to improve body weight distribution and balance.
Importance of curvatures
These curvatures are important because they help to evenly distribute
the pressure on the spine and maintain the body's balance during movement and daily activities.
Euler's law
The existence of vertebral curvatures also confers strength properties on the spine.
The “Euler's Law” defines the spine resistance by the number of its curvatures.
Resistance (R) = (Nb curvatures)² +1
thus, a column with 3 curvatures has 10 times more resistance than a straight column.
Note: Sacrococcygeal curvature is not taken into account in this calculation.
