Osteology of the Skull

Study Guide: Osteology of the Skull

Learning Objective 1: Neurocranium Bones and Their Features

• 8 Bones of the Neurocranium:
  • Frontal (1):
  • Location: Forehead
  • Features: Contains frontal sinuses
  • Parietal (2):
  • Location: Sides and roof of cranial cavity
  • Temporal (2):
  • Location: Lower sides of skull
  • Features:
    • Mandibular fossa
    • Styloid and mastoid processes
  • Occipital (1):
  • Location: Back and base of skull
  • Features:
    • Foramen magnum
    • Occipital condyles
  • Ethmoid (1):
  • Location: Between orbits
  • Features: Crista galli and cribriform plate
  • Sphenoid (1):
  • Shape: Butterfly-shaped
  • Features: Houses the sella turcica for the pituitary gland
• Cranial Fossae:
  • Anterior
  • Middle
  • Posterior

Learning Objective 2: Facial Bones and Their Features

• 14 Facial Bones (Viscerocranium):
  • Zygomatic (2): Cheekbones
  • Maxilla (2): Upper jaw; contains maxillary sinuses
  • Palatine (2): Back of hard palate
  • Lacrimal (2): Near tear ducts
  • Nasal (2): Bridge of nose
  • Vomer (1): Forms the nasal septum
  • Inferior Nasal Concha (2): Located in nasal cavity
  • Mandible (1): Lower jaw
• Orbit: Formed by 7 bones and includes 3 foramina

Learning Objective 3: Sutures of the Skull

• Four Sutures:
  • Coronal:
  • Bones: Frontal + Parietal
  • Sagittal:
  • Bones: Between Parietal bones
  • Lambdoidal:
  • Bones: Parietal + Occipital
  • Squamosal:
  • Bones: Temporal + Parietal

Learning Objective 4: Bony Landmarks on the Skull

• Superior Surface Features:
  • Frontal Crest
  • Crista Galli
  • Cribriform Plate
  • Sella Turcica
  • Clivus
• Inferior Surface Features:
  • Medial/Lateral Pterygoid Plates
  • Pterygoid Fossa
  • Zygomatic Arch
  • Mandibular Fossa
  • Styloid & Mastoid Processes
  • Occipital Condyle
  • Inion

Learning Objective 5: Bony Landmarks of the Mandible

• Mandible Features:
  • Ramus
  • Body
  • Angle
  • Condyloid Process
  • Coronoid Process
  • Mandibular Foramen
  • Genial Spine
  • Mental Foramen
• TMJ:
  • Formed by: Condyloid Process + Mandibular Fossa

Learning Objective 6: Paranasal Sinuses

• Paranasal Sinuses are found in 4 bones:
  • Frontal
  • Ethmoid
  • Sphenoid
  • Maxillary
• Function:
  • Lighten skull
  • Voice resonance
  • Mucosal lining
• Mnemonic: FEMS (Frontal, Ethmoid, Maxillary, Sphenoid)

Learning Objective 7: Major Foramina of the Skull

• Major Foramina:
  • Foramen Magnum: Transmits medulla and vertebral arteries
  • Optic Canal: Transmits CN II
  • Superior Orbital Fissure: Transmits CN III, IV, V1, VI
  • Foramen Ovale: Transmits CN V3
  • Jugular Foramen: Transmits CN IX, X, XI and jugular vein
  • Hypoglossal Canal: Transmits CN XII
  • Mental Foramen: Transmits mental nerve
  • Mandibular Foramen: Transmits inferior alveolar nerve

Practice Questions

1. Which bones contribute to the orbit of the eye?
2. Which bone contains the cribriform plate and crista galli?
3. Which sinus is most commonly infected and located under the eyes?
4. What foramen transmits the mandibular branch of CN V?
5. What bones form the squamosal suture?