Overview
This lecture covers the anatomy and regional divisions of the vertebral column, its structural features, spinal curvature types, and distinguishing characteristics of vertebrae in each spinal region.
Structure and Regions of the Vertebral Column
- The vertebral column (spine) is the central part of the axial skeleton, running from the skull to the tailbone.
- It is composed of 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, and 3–5 fused coccygeal vertebrae.
- Spinal regions are divided based on function and vertebral structure.
Spinal Curvatures and Clinical Relevance
- The spine has physiological curvatures: primary (thoracic and sacral kyphosis) and secondary (cervical and lumbar lordosis).
- Primary curvatures are present at birth; secondary curvatures develop as a child lifts their head and walks.
- Exaggeration of curves can cause kyphosis (hunchback), lordosis (swayback), or scoliosis (lateral curve).
Basic Vertebral Structure
- Most vertebrae share three main components: vertebral body, vertebral arch (lamina and pedicle), and processes.
- The vertebral foramen forms the vertebral canal, housing the spinal cord and meninges.
- Processes include spinous, transverse, superior, and inferior articular processes; intervertebral foramen allow spinal nerve exit.
- Intervertebral discs sit between vertebral bodies, providing flexibility and shock absorption.
Cervical Vertebrae (C1–C7)
- Typical cervical vertebrae have a transverse foramen for vertebral arteries and bifid spinous processes (except C1, C7).
- C1 (atlas) lacks a body, has anterior/posterior arches, and articulates with the occipital bone.
- C2 (axis) has a prominent dens (odontoid process), enabling head rotation.
- The "carotid tubercle" (C6) is clinically important for carotid artery compression.
Thoracic Vertebrae (T1–T12)
- Typical thoracic vertebrae (T2–T9) have costal facets for rib attachment (superior, inferior, transverse).
- Atypical thoracic vertebrae (T1, T10–T12) differ in facet number and rib articulation.
- Thoracic vertebrae form thoracic kyphosis and limit movement due to rib connections.
Lumbar Vertebrae (L1–L5)
- Large, strong vertebrae with kidney-shaped bodies to support body weight.
- Transverse processes are called costal processes—embryological remnants of ribs.
Sacrum and Coccyx
- The sacrum consists of 5 fused vertebrae, forming sacral kyphosis, with a base, apex, and sacral canal.
- Sacral foramina transmit sacral nerves; crests are formed by fusion of processes.
- Coccyx is 3–5 fused vertebrae (tailbone) with cornua (remnant horns).
Key Terms & Definitions
- Vertebral foramen — large opening for the spinal cord through each vertebra
- Spinous process — posterior projection for muscle/ligament attachment
- Transverse process — lateral projections, may have foramina or costal facets
- Dens (odontoid process) — upward projection from C2 (axis) for head rotation
- Lordosis — inward spinal curvature (cervical, lumbar)
- Kyphosis — outward spinal curvature (thoracic, sacral)
- Scoliosis — abnormal lateral curvature of the spine
- Intervertebral disc — fibrocartilaginous structure between vertebral bodies for shock absorption
Action Items / Next Steps
- Review ligament structure and functions connecting the vertebral column in the next lecture or assigned reading.