2. vertebral column

Vertebral Column Overview

  • Author: Sophio Kakabadze, MD

General Structure

  • The vertebral column has a double-S shape.

  • Composed of 33 vertebrae (range of 32-35).

  • Differentiated into several regions:

    • Cervical

    • Thoracic

    • Lumbar

    • Sacral

    • Coccygeal

Functions of the Vertebral Column

  • Protection of the spinal cord, spinal nerve roots, and associated vasculature.

  • Weight transfer from the upper body to the pelvis.

  • Articulation with the skull, ribs, and pelvis.

  • Allows for flexion and extension through its vertebral articulations.

  • Serves as an attachment site for muscles, including the diaphragm and pelvic floor.

Curvature of the Vertebral Column

  • Lordosis: Convex anteriorly in the cervical and lumbar regions.

  • Kyphosis: Convex posteriorly in the thoracic and sacral regions.

Regions of the Vertebral Column

  • Cervical Vertebrae: 7

  • Thoracic Vertebrae: 12

  • Lumbar Vertebrae: 5

  • Sacrum: 5 (fused)

  • Coccyx: 4 (fused)

Basic Vertebral Structure

  • Vertebral Body:

    • Cylindrical anterior part responsible for weight-bearing.

    • Articulates with adjacent vertebral bodies via the intervertebral disc.

  • Vertebral Arch:

    • Composed of:

      • Pedicles (laterally)

      • Laminae (posteriorly) with processes.

Components of the Vertebral Arch

  • Vertebral Pedicles:

    • Lateral parts between the vertebral body and laminae.

    • Form vertebral notches that create intervertebral foramina for nerve passage.

  • Intervertebral Foramina:

    • Allow spinal nerves and their vessels to exit.

    • C1–C7 nerves exit superiorly and C8 exits inferiorly.

    • T1 and subsequent nerves exit inferiorly to their corresponding vertebral bodies.

  • Vertebral Laminae:

    • Posterior part between transverse and spinous processes.

    • Attachment site for ligamentum flavum.

  • Processes:

    • Spinous Process:

      • Single midline process at the junction of the laminae.

    • Transverse Processes:

      • Postero-lateral processes at the junction of the pedicles and laminae.

  • Articular Processes:

    • Surfaces that articulate with adjacent vertebrae.

Vertebral Foramen and Canal

  • Vertebral Foramen: Central space encircled by the body and arch; forms the vertebral canal housing the spinal cord and associated structures.

Intervertebral Discs

  • Composed of:

    • Nucleus Pulposus: Gelatinous core.

    • Annulus Fibrosus: Surrounding fibrocartilaginous layers.

  • Thickest in lumbar region, absent between atlas and axis (C1 and C2).

Facet Joints

  • Articulate between articular processes, allowing for movement (flexion, extension, rotation).

Ligaments of the Spine

  • Anterior Longitudinal Ligament: Limits extension, runs from occipital bone to sacrum.

  • Posterior Longitudinal Ligament: Limits flexion, runs along the posterior surface of the vertebral bodies.

  • Ligamenta Flava: Form posterior wall of spinal canal; support upright posture.

  • Nuchal Ligament: Limits flexion of the cervical spine.

  • Supraspinous Ligament: Connects tips of spinous processes; limits flexion.

  • Interspinous Ligaments: Limit flexion between spinous processes.

  • Intertransverse Ligaments: Limit lateral flexion between transverse processes.

Spine Movement Ranges

  • Extension/Flexion: Varies by region.

    • Cervical: 45°-90°

    • Thoracic: 20°-45°

    • Lumbar: 20°-40°

Unique Characteristics of the Vertebrae

  • Atlas (C1): No vertebral body; forms atlanto-occipital and atlanto-axial joints.

  • Axis (C2): Contains odontoid process (dens), allows rotation.

  • Cervical Vertebrae: Large foramina for spinal cord enlargement.

  • Thoracic Vertebrae: Articulate with ribs via demifacets.

  • Lumbar Vertebrae: Largest vertebral bodies supporting body weight.

  • Sacrum: 5 fused vertebrae; smaller female sacral promontory compared to males.

  • Coccyx: 3–5 fused rudimentary vertebrae.

Sacroiliac Joints

  • Synovial joints between the ilium and sacrum, allowing limited movement.