Cranium and Facial Bones Anatomy

Cranium

• The cranium is the upper part of the skull, forming the brain case
• Composed of 8 bones that fuse together during childhood and adolescence
• Bones of the cranium:
  1. Frontal bone
  2. Parietal bone (2)
  3. Occipital bone
  4. Temporal bone (2)
  5. Sphenoid bone
  6. Ethmoid bone

Facial Bones

• The facial bones form the upper and lower jaws, nose, and orbit (eye socket)
• 14 bones in total, including:
  1. Vomer bone
  2. Zygoma bone (2)
  3. Maxilla bone (2)
  4. Lacrimal bone (2)
  5. Palatine bone (2)
  6. Inferior nasal conchae (2)
  7. Mandible (lower jawbone)
  8. Nasal bone (2)

Paranasal Sinuses

• Air-filled cavities in the skull bones that reduce weight and humidity the air we breathe
• Four pairs of paranasal sinuses:
  1. Maxillary sinuses (in maxilla bones)
  2. Frontal sinuses (in frontal bone)
  3. Ethmoid sinuses (in ethmoid bone)
  4. Sphenoid sinuses (in sphenoid bone)

Foramen

• Foramen (Latin for "hole") are openings in the skull bones for passage of nerves, arteries, and veins
• Examples of foramen:
  1. Foramen magnum (transmits spinal cord)
  2. Foramen ovale (transmits mandibular nerve)
  3. Foramen spinosum (transmits middle meningeal artery)
  4. Foramen lacerum (transmits internal carotid artery)

Mandible

• The mandible is the lower jawbone
• Composed of a horizontal body and two vertical rami (branches)
• Functions:
  1. Forms the lower jaw and supports the teeth
  2. Acts as an attachment site for muscles of mastication (chewing)
  3. Contains the mandibular canal, which houses the inferior alveolar nerve and vessels

Cranium

• The cranium is the upper part of the skull, forming the brain case
• Composed of 8 bones that fuse together during childhood and adolescence
• The 8 bones of the cranium include the frontal, parietal, occipital, temporal, sphenoid, and ethmoid bones

Facial Bones

• The facial bones form the upper and lower jaws, nose, and orbit (eye socket)
• There are 14 facial bones, including the vomer, zygoma, maxilla, lacrimal, palatine, inferior nasal conchae, and nasal bones
• The mandible is the lower jawbone and is also part of the facial bones

Paranasal Sinuses

• Paranasal sinuses are air-filled cavities in the skull bones that reduce weight and humidity the air we breathe
• There are four pairs of paranasal sinuses: maxillary, frontal, ethmoid, and sphenoid sinuses
• Each pair of sinuses is located in a specific bone: maxilla, frontal, ethmoid, and sphenoid bones, respectively

Foramen

• Foramen are openings in the skull bones that allow passage of nerves, arteries, and veins
• Examples of foramen include the foramen magnum, foramen ovale, foramen spinosum, and foramen lacerum
• The foramen magnum transmits the spinal cord, while the foramen ovale transmits the mandibular nerve

Mandible

• The mandible is the lower jawbone, composed of a horizontal body and two vertical rami (branches)
• The mandible forms the lower jaw and supports the teeth
• It also acts as an attachment site for muscles of mastication (chewing) and contains the mandibular canal, which houses the inferior alveolar nerve and vessels

Cranium

• Protects the brain
• Comprises 8 fused bones in adulthood, including:
  • Frontal bone
  • Parietal bone (2)
  • Occipital bone
  • Temporal bone (2)
  • Sphenoid bone
  • Ethmoid bone
• Functions include:
  • Brain protection
  • Muscle attachment site for head and neck
  • Support for facial bones

Mandible

• Lower jawbone and only movable skull bone
• Forms the lower jaw and supports:
  • Teeth
  • Opening and closing of the mouth

Foramina

• Holes or openings in the skull for passage of:
  • Nerves (e.g., mandibular nerve through foramen ovale)
  • Blood vessels (e.g., middle meningeal artery through foramen spinosum)
  • Other structures (e.g., spinal cord through foramen magnum)
• Examples of foramina include:
  • Foramen magnum
  • Foramen ovale
  • Foramen spinosum
  • Optic foramen

Facial Bones

• Form the upper and lower jaws, nose, and orbit (eye socket)
• Consist of 14 bones, including:
  • Vomer
  • Zygoma (2)
  • Maxilla (2)
  • Lacrimal bone (2)
  • Palatine bone (2)
  • Inferior nasal conchae (2)
  • Mandible
• Functions include:
  • Supporting facial structures
  • Forming upper and lower jaws
  • Supporting teeth

Paranasal Sinuses

• Air-filled cavities in the skull connected to the nasal cavity
• Four pairs of paranasal sinuses, including:
  • Maxillary sinuses (in maxilla bones)
  • Frontal sinuses (in frontal bone)
  • Ethmoid sinuses (in ethmoid bone)
  • Sphenoid sinuses (in sphenoid bone)
• Functions include:
  • Warming, humidifying, and filtering the air
  • Reducing skull weight
  • Adding resonance to the voice