Cranial Bones Overview

Introduction

• Focus on cranial bones: part of the skull that protect the brain.
• Total skull bones: 22 (8 cranial, 14 facial).

Mnemonic for Cranial Bones

• Mnemonic: "Eight Osseous Parts Form The Skull"
• Bones Included:
  • Ethmoid Bone
  • Occipital Bone
  • Parietal Bone (2 of them)
  • Frontal Bone
  • Temporal Bone (2 of them)
  • Sphenoid Bone

Detailed Anatomy

Ethmoid Bone

• Location: Roof of the nose, between the orbits.
• Functions & Features:
  • Separates nasal cavity from the brain.
  • Articulates with frontal and sphenoid bones.
  • Contains ethmoid sinus.
  • Cribriform Plate: Passage for olfactory nerves.
  • Crista Galli: Attaches brain to skull.

Occipital Bone

• Location: Back of the skull.
• Features:
  • Lambdoid Suture: Connects with parietal bones, shaped like a lambda.
  • External Occipital Protuberance: Bump for neck muscle attachment.
  • Occipital Condyles: Articulate with first cervical vertebra (C1/Atlas).
  • Foramen Magnum: Passage for brain stem.

Parietal Bones

• Location: Either side of the skull.
• Sutures:
  • Coronal Suture: Connects to frontal bone.
  • Squamous Suture: Connects to temporal bones.
  • Lambdoid Suture: Connects to occipital bone.
  • Sagittal Suture: Connects the two parietal bones.

Frontal Bone

• Location: Forehead, superior part of orbits.
• Features:
  • Supraorbital Foramen: Passage for supraorbital nerve.
  • Connects to parietal bones via coronal suture.

Temporal Bones

• Location: Side of the skull.
• Features:
  • Zygomatic Process: Part of zygomatic arch (cheekbone).
  • Auditory Meatus: Canal to inner ear.
  • Mastoid Process: Attachment for neck muscles.
  • Styloid Process: Attachment for tongue and larynx muscles.
  • Mandibular Fossa: Articulation point for mandible.

Sphenoid Bone

• Unique: Articulates with all other cranial bones.
• Features:
  • Sella Turcica: Houses the pituitary gland.
  • Other Parts: Greater wing, lesser wing, pterygoid processes, body.

Conclusion

• This lecture helped simplify cranial bone anatomy.
• Further details on facial bones will be covered separately.
• Additional learning resources and notes available on the Easy Med blog.
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