BIOL117: Axial Skeleton Quiz

Axial Skeleton

• Comprises bones of the skull, vertebral column, ribs, and sternum.

Skull Bones

• Frontal Bone: Forms the forehead.
• Temporal Bone: Located at the sides of the skull, contains structures related to hearing.
  • Mastoid Process: Bony prominence behind the ear.
  • External Auditory Meatus: Canal leading to the inner ear.
• Parietal Bone: Forms the top and sides of the skull.
• Occipital Bone: Forms the back of the skull.
  • Foramen Magnum: Large opening for spinal cord passage.
• Sphenoid Bone: Butterfly-shaped bone that forms part of the cranial floor.
• Ethmoid Bone: Contributes to the nasal cavity and orbits.
• Vomer Bone: Forms part of the nasal septum.
• Nasal Bone: Forms the bridge of the nose.
• Maxilla: Upper jawbone, holding upper teeth.
• Mandible: Lower jawbone, only movable bone of the skull.
  • Ramus: Vertical part of the mandible.
• Lacrimal Bone: Small bone forming part of the eye socket.
• Palatine Bone: Forms part of the hard palate of the mouth.
• Zygomatic Bone: Cheekbone, contributing to the orbit.
• Hyoid Bone: U-shaped bone in the neck, supports the tongue.

Vertebral Column

• Composed of cervical (C1-C7), thoracic (T1-T12), lumbar (L1-L5), sacral (S1-S5), and coccygeal vertebrae (3).

Cervical Vertebrae

• Atlas (C1): Supports the skull, lacks a vertebral body.
• Axis (C2): Features the dens (odontoid process) allowing head rotation.

Vertebral Structure

• Vertebral Body: Weight-bearing portion.
• Vertebral Foramen: Canal for spinal cord.
• Spinous Processes: Bony projections where muscles attach.
• Transverse Processes: Lateral extensions for muscle attachment.
• Lamina: Connects spinous and transverse processes.
• Pedicle: Connects the body to the lamina.
• Vertebral Arch: Encircles the vertebral foramen.
• Articular Facets: Connect adjacent vertebrae for stability.

Intervertebral Discs

• Nucleus Pulposus: Inner gel-like core, shock absorber.
• Annulus Fibrosis: Outer ring, contains nucleus and distributes pressure.

Ribs and Sternum

• Types of Ribs:
  • True Ribs (7): Directly attach to sternum via costal cartilage.
  • False Ribs (3): Indirectly attach through shared cartilage.
  • Floating Ribs (2): No sternum attachment.
• Sternum:
  • Jugular Notch: Central notch at the top.
  • Manubrium: Upper portion of the sternum.
  • Body: Central portion.
  • Xiphoid Process: Small, lower segment of the sternum.

Review Questions

• Anatomical name for jawbone: Mandible.
• Forehead bone: Frontal.
• Eye socket name: Orbit.
• Anatomical name for the C1 vertebra: Atlas.
• Inner jelly of intervertebral discs: Nucleus pulposus.
• Number of thoracic vertebrae: 12.