Normal Thoracic Spine Shape
The normal thoracic spine, when viewed from the side (sagittal plane), is kyphotic—meaning it curves with a posterior convexity (curves outward away from the front of the body).
Anatomical Description
The thoracic spine demonstrates a dorsally convex curvature in the sagittal plane, which is the defining characteristic of kyphosis 1. This posterior convexity is the normal anatomical configuration that distinguishes the thoracic region from other spinal segments.
Normal Range and Measurement
- Normal thoracic kyphosis (T1-T12) averages approximately 49.5 degrees in asymptomatic adults, with the customary measurement taken between T4 and T12 averaging 41.5 degrees 2
- The apex of this kyphotic curve is typically located at T6-T7, with T7 positioned horizontally regardless of the total kyphosis magnitude 2
- Pathological kyphosis is defined as a Cobb angle greater than 50 degrees in the thoracic spine 1
Clinical Context
Understanding this normal kyphotic shape is essential because:
- Deviations from normal thoracic kyphosis can indicate pathology, such as in adolescent idiopathic scoliosis where the thoracic spine often shows reduced kyphosis or even lordosis (reversal of normal curvature) 3, 4
- In scoliosis patients, the sagittal plane curvature is typically 7.72 ± 9.9 degrees less than in non-scoliotic populations 4
- The thoracic spine's unique anatomy with rib attachments and proximity to vital structures makes understanding its normal curvature critical for surgical planning 5
Answer: The thoracic spine is kyphotic (curves outward/posteriorly when viewed from the side).