Axial Skeleton 2: Vertebrae, Ribs, Sternum Exercise 8

Introduction to the Axial Skeleton

  • Composed of 80 bones: skull, hyoid, vertebrae, sternum, auditory ossicles, ribs.

  • Focus on vertebrae, ribs, sternum (skull and hyoid excluded from this section).

Vertebral Column

  • Regions of the Vertebral Column:

    • Cervical (C1-C7)

    • Thoracic (T1-T12)

    • Lumbar (L1-L5)

    • Sacrum (S1-S5, fused)

    • Coccyx (generally 4 coccygeal vertebrae, Co1-Co4)

  • Total vertebrae: 33 individual vertebrae

    • Some fuse to form larger structures (e.g., sacrum).

Thoracic Cage

  • Composed of:

    • 12 pairs of ribs

    • Thoracic vertebrae

    • Sternum

  • Functions include:

    • Protection of lungs and heart

    • Flexibility during breathing.

Learning Objectives

  1. Locate specific vertebrae (e.g., T6).

  2. Name selected vertebrae.

  3. Identify bony features of individual vertebrae and their regions.

  4. Recognize atlas and axis vertebrae.

  5. Describe normal and abnormal spinal curvatures.

  6. Differentiate types of ribs and their markings.

  7. Demonstrate major regions of the sternum.

Materials Needed

  • Articulated skeleton or casts.

  • Disarticulated bones or casts.

  • Charts of the skeletal system.

  • Cut drinking straws or pipe cleaners for pointing.

  • Foam pads for protecting bones from hard surfaces.

  • Cardboard box or wood piece for displays.

Overview of Vertebrae

  • Unique human features:

    • Bipedalism leads to size increase from cervical to lumbar due to weight.

    • Vertebral canal diameter increases from sacral to cervical regions (more neural fibers in cervical area).

  • Intervertebral discs: fibrocartilaginous pads between vertebrae.

Cervical Vertebrae (C1-C7)

  • Key Features:

    • Each has three foramina: one vertebral foramen (largest) and two transverse foramina (for arteries/veins).

    • Bifid spinous processes (C2-C6).

  • Special Vertebrae:

    • C1 (Atlas): No body, allows nodding "yes."

    • C2 (Axis): Dens (odontoid process) allows rotation of head, indicating "no."

    • C7 (Vertebra Prominens): Distinctive spinous process for palpation

Thoracic Vertebrae (T1-T12)

  • Distinguished by rib attachment points:

    • Costal Facets:

    • Complete costal facet for single rib attachment.

    • Superior and inferior costal facets for attachment to two vertebrae.

  • Longer spinous processes; angles inferiorly.

  • Lacks transverse foramina.

Lumbar Vertebrae (L1-L5)

  • No transverse foramina or rib facets.

  • Horizontal spinous processes; larger bodies to bear weight.

  • Notably similar to last thoracic vertebra (T12).

Sacrum

  • Structure: Large, wedge-shaped bone composed of five fused vertebrae.

  • Features:

    • Transverse lines indicate fusion points.

    • Anterior sacral foramina and posterior sacral foramina for nerve passage.

    • Auricular surfaces for sacroiliac joint.

    • Wedge shape supports upper body better than a rectangular sacrum.

Coccyx

  • Composed of general four vertebrae (Co1-Co4) at the inferior end of the vertebral column.