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Bones of the Trunk

  • Comprises vertebral column, individual vertebrae, ribs, sternum, and clavicle.

Ligaments of the Trunk

  • Lengthwise ligaments along the vertebral column and those connecting the sternum to the clavicles/ribs.

Vertebral Column

  • Also known as spine or spinal column.

  • Consists of individual vertebrae; 33 in childhood, 26 in adults due to fusion.

  • Regions:
      - 7 cervical vertebrae (neck)
      - 12 thoracic vertebrae (posterior to ribs)
      - 5 lumbar vertebrae (lower back)
      - 1 sacrum (5 fused vertebrae)
      - 1 coccyx (4 fused vertebrae)

Normal Curvatures

  • Appears straight from anterior/posterior view, but has four curves when viewed from the side:
      - Cervical and lumbar curves (convex)
      - Thoracic and sacral curves (concave)

Key Vertebral Structures

  • Vertebral body: thick disc-shaped front portion.

  • Vertebral foramen: central hole for spinal cord.

  • Intervertebral foramina: holes for spinal nerves.

  • Processes:
      - 2 transverse processes (lateral)
      - 1 spinous process (posterior)
      - 2 superior/inferior articulating processes.

Types of Vertebrae

  • Cervical: smaller bodies, three foramina, C1 (atlas) lacks body and spinous process, C2 (axis) has dens for rotation.

  • Thoracic: larger, distinguished by downward-pointing spinous processes; possess costal facets for rib articulation.

  • Lumbar: largest and strongest, large oval bodies, short thick processes.

  • Sacrum: triangular, formed from fused sacral vertebrae, contains auricular surfaces for pelvic articulation.

  • Coccyx: formed from fused coccygeal vertebrae.

Intervertebral Discs and Ligaments

  • Intervertebral discs: absorb shock and allow movement.

  • Key ligaments:
      - Anterior Longitudinal Ligament: runs along the front.
      - Posterior Longitudinal Ligament: runs along the back.
      - Supraspinous Ligament: connects spinous processes.

Sternum and Ribs

  • Sternum: flat, centrally located; consists of manubrium, body, xiphoid process.

  • Ribs: 12 pairs, increasing and then decreasing in length; types:
      - True ribs (1-7): attach directly to sternum.
      - False ribs (8-10): attach indirectly.
      - Floating ribs (11-12): do not attach to sternum.

Clavicle

  • Slender, S-shaped bone; connects to manubrium (medial end) and scapula (lateral end).

  • Features: subclavian groove for muscle attachment and ligaments connecting to the sternum/ribs.