Vertebral Column Overview¶
Definition¶
The vertebral column (spine) is the central bony structure of the axial skeleton, consisting of 33 vertebrae in total — 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 4 fused coccygeal segments. It serves as the primary structural support for the trunk, protects the spinal cord and nerve roots, and provides attachment points for the ribs and muscles of the trunk.
Vertebral Regions¶
The vertebral column is divided into five distinct regions, each with characteristic structural and functional properties:
| Region | Vertebrae | Curvature | Motion |
|---|---|---|---|
| Cervical | C1–C7 | Lordosis | Greatest mobility, especially rotation and flexion/extension |
| Thoracic | T1–T12 | Kyphosis | Limited by rib cage articulation |
| Lumbar | L1–L5 | Lordosis | Primarily flexion/extension, limited rotation |
| Sacral | S1–S5 (fused) | Kyphosis | No motion (fused) |
| Coccygeal | Co1–Co4 (fused) | — | Minimal |
General Vertebral Anatomy¶
A typical vertebra consists of two main parts:
Anterior element — Vertebral body:
- Weight-bearing structure that increases in size from cervical to lumbar
- Composed of trabecular (cancellous) bone surrounded by a cortical shell
- Superior and inferior surfaces are the vertebral endplates, covered by hyaline cartilage
Posterior elements — Vertebral arch:
- Pedicles — paired bony projections connecting the body to the posterior elements
- Laminae — paired flat plates connecting the pedicles to the spinous process
- Spinous process — midline posterior projection for muscle and ligament attachment
- Transverse processes — paired lateral projections for muscle and ligament attachment
- Superior and inferior articular processes — form the facet (zygapophyseal) joints
- Vertebral foramen — the central canal formed by the body and arch, housing the spinal cord
Clinical Pearl
The vertebral canal is widest in the cervical and lumbar regions, corresponding to the cervical and lumbar enlargements of the spinal cord. Stenosis is most clinically significant at these levels due to the density of neural structures.
Spinal Curvatures¶
The adult vertebral column exhibits four physiologic curves when viewed in the sagittal plane:
- Cervical lordosis — develops as infants begin to hold their heads up
- Thoracic kyphosis — a primary curvature present from fetal development
- Lumbar lordosis — develops when children begin to walk
- Sacral kyphosis — a primary curvature, fixed due to sacral fusion
These curvatures provide a spring-like mechanism that absorbs axial loads during standing, walking, and impact. Loss or exaggeration of normal curvatures is often associated with pathology.
Imaging Findings¶
Radiography (X-ray)¶
Standard radiographic evaluation of the spine includes:
- AP view — assesses vertebral body alignment, pedicle spacing, disc space heights, and scoliosis
- Lateral view — evaluates curvatures, vertebral body heights, disc spaces, and alignment
- Flexion/extension views — dynamic evaluation of segmental stability
Key Radiographic Landmarks
On the lateral view, three smooth contour lines should be assessed: the anterior vertebral body line, the posterior vertebral body line, and the spinolaminar line. Disruption of any of these lines suggests malalignment or injury.
CT¶
CT provides excellent osseous detail and is preferred for evaluating:
- Fractures, particularly complex or occult fractures
- Bony canal dimensions and foraminal stenosis
- Post-surgical hardware positioning
- Osseous lesions
MRI¶
MRI is the gold standard for evaluating soft tissue structures of the spine:
| Sequence | Vertebral Body Signal | Key Utility |
|---|---|---|
| T1-weighted | Intermediate to bright (fatty marrow) | Marrow evaluation, anatomy |
| T2-weighted | Intermediate | Disc evaluation, fluid detection |
| STIR | Suppressed marrow fat | Edema, inflammation, infiltrative disease |
| Post-contrast T1 | Enhancement pattern varies | Infection, tumor, post-surgical evaluation |
Key Points¶
- The vertebral column consists of 33 vertebrae organized into 5 regions
- Normal sagittal curvatures include cervical and lumbar lordosis and thoracic and sacral kyphosis
- Each vertebra has an anterior body for weight-bearing and a posterior arch protecting the spinal cord
- Radiographic alignment is assessed using three smooth contour lines on the lateral view
- MRI is the preferred modality for soft tissue and spinal cord evaluation
References¶
- DeSai C, Reddy V, Agarwal A. Anatomy, Back, Vertebral Column. StatPearls. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK525969/
- DeSai C, Jozsa F, Agarwal A. Neuroanatomy, Spine. StatPearls. NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK526133/
- Jones J, et al. Vertebral column. Radiopaedia.org. https://radiopaedia.org/articles/vertebral-column
- TeachMeAnatomy. The Vertebral Column — Structure, Regions & Function. https://teachmeanatomy.info/back/bones/vertebral-column/
- Kenhub. Vertebral column: Anatomy, vertebrae, joints & ligaments. https://www.kenhub.com/en/library/anatomy/the-vertebral-column-spine