Axial Skeleton and Skull Anatomy

Axial Skeleton

• Includes bones along the midline axis.
• Comprises the bones of the skull, thoracic cage (ribcage), and vertebral column.
• Vertebral column protects the spinal cord.

Skull

• Refer to diagrams in the textbook (OpenStax book) for various views: anterior, lateral, inferior, internal (superior), and posterior.
• Bones are often color-coded in these diagrams.

Cranial Bones

• Form the brain case, protecting the brain.

Frontal Bone

• Main bone of the forehead.
• Protects the brain.
• Protects the eye by forming the roof/top of the orbit (eye socket).
• "Frontal" means forehead.

Parietal Bones

• Large bones forming most of the superior and lateral aspects of the skull.

Temporal Bones

• Located at the temples.
• Contain features related to the ear.
• External Auditory (Acoustic) Meatus:
  • Hole in the temporal bone.
  • Meatus = canal.
  • Carries sound waves to the tympanic membrane (eardrum).
• Temporomandibular Joint:
  • Temporal bone articulates with the mandible.
• Mandibular Fossa:
  • Shallow depression on the temporal bone.
  • Site where the mandible articulates to form the temporomandibular joint.
  • Fossa = depression; often found at joints.
• Mastoid Process:
  • Projection or lump on the skull.
  • Attachment site for the sternocleidomastoid muscle.
  • Sternocleidomastoid muscle allows:
    • Head turning (left and right, like saying "no").
    • Head nodding/flexion.

Occipital Bone

• Forms most of the posterior and inferior aspects of the skull.
• Foramen Magnum:
  • Large hole in the occipital bone.
  • Accommodates the spinal cord.
  • Marks the end of the brainstem and the beginning of the spinal cord.
  • Foramen = hole.
  • "Magnum" translates to "great" or "large"
• Occipital Condyles:
  • Two rounded lumps lateral to the foramen magnum.
  • Site where the first cervical vertebra (C1 or Atlas) articulates with the skull.
  • Allows gliding movement of the head from side to side against the Atlas.