Vertebral Column and Thoracic Cage Overview

Overview

This lecture covers the vertebral column and thoracic cage, including their structure, regions, functions, curvatures, clinical conditions, and the organization of the ribs and sternum.

Vertebral Column Structure & Function

• The vertebral column supports the skull and trunk, allows movement, protects the spinal cord, absorbs stress, and provides muscle/limb attachments.
• There are 26 vertebrae divided into 5 regions: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral (by mid-20s), and 3-5 fused coccygeal bones (by age 30).
• A typical vertebra has seven processes: one spinous, two transverse, and four articular processes.
• The vertebral foramen houses the spinal cord; vertebral bodies are separated by intervertebral discs.

Specialized Vertebrae & Joints

• The Atlas (C1) has no body and forms a condylar (yes motion) joint with the occipital bone.
• The Axis (C2) has a dens (odontoid process) providing a pivot joint for rotation (no motion) with the atlas.
• Superior and inferior vertebral notches form intervertebral foramina for spinal nerves.

Intervertebral Discs & Disorders

• Intervertebral discs are fibrocartilage with a pulpy center that absorb vertical shock and allow movement.
• Herniated (slipped) discs occur when the annulus cracks, pressing on nerves or the spinal cord, often in the lumbar region.

Curvatures of the Spine

• Primary curvatures (present at birth): thoracic and sacral.
• Secondary curvatures develop later: cervical (when holding up the head) and lumbar (when sitting/walking).
• Adults have four normal curvatures: cervical lordosis, thoracic kyphosis, lumbar lordosis, and pelvic kyphosis.

Clinical Abnormalities

• Hyperkyphosis: exaggerated thoracic curvature, seen in osteoporosis, osteomalacia, tuberculosis, and young weightlifters.
• Hyperlordosis: exaggerated lumbar curvature.
• Scoliosis: lateral curvature, most common in adolescent girls; can deform ribs and scapula, sometimes impairing mobility.

Thoracic Cage & Ribs

• The sternum consists of the manubrium, body, and xiphoid process.
• Ribs 1-7 are true ribs (direct cartilage connection to the sternum).
• Ribs 8-10 are false ribs (indirect cartilage connection via rib above).
• Ribs 11-12 are floating ribs (no anterior attachment); sometimes classified as false or floating ribs.

Key Terms & Definitions

• Vertebral Foramen — opening where the spinal cord passes through a vertebra.
• Articular Process — projection that forms joints between vertebrae.
• Atlas — first cervical vertebra (C1) supporting the skull.
• Axis — second cervical vertebra (C2) with dens for rotation.
• Intervertebral Disc — fibrocartilage pad between vertebrae.
• Herniated Disc — rupture of the intervertebral disc's outer layer, pressing on nerves.
• Kyphosis — outward (posterior) curvature, usually thoracic.
• Lordosis — inward (anterior) curvature, usually lumbar or cervical.
• Scoliosis — abnormal lateral curvature of the spine.
• True Ribs — ribs directly attached to sternum via cartilage (1-7).
• False Ribs — ribs with indirect cartilage attachment (8-10).
• Floating Ribs — ribs with no anterior attachment (11-12).

Action Items / Next Steps

• Review diagrams of vertebrae and thoracic cage.
• Learn the typical numbers and regions of vertebrae.
• Prepare for the next lecture covering the remainder of the skeleton.