OH3: Dental Anatomy Review

OH3 - Dental Anatomy: Course Overview To Date

• The Tooth Structures: Covered in previous sessions.
• The Supporting Structures: Explored previously.
• Deciduous and Permanent Dentitions: Understanding the two stages of tooth development.
• The Oral Cavity: Detailed study of the mouth's interior.
• Soft Tissues Conditions: Examination of various conditions affecting oral soft tissues.
• Conditions of the Oral Cavity: General diseases and disorders.
• Saliva, Glands, Ducts: Functions and anatomy of salivary components.
• Muscles of Mastication: Initial introduction to the chewing muscles.
• Dental Charting – Handwritten: Practical skills in documenting dental information.
• Tooth Morphology: Study of the form and structure of teeth.
• The Skull – Facial & Cranial Bones: Introduction to the bones of the head.
• The Mandible: Initial focus on the lower jaw bone.

The Skull: Bones of the Cranium and Face

Cranial Bones

• Frontal Bone:
  • One plate forming the forehead.
  • Features include the supraorbital foramen and orbital part.
• Parietal Bones:
  • Two plates joined together centrally along the top of the skull.
  • Form the majority of the sides and back of the skull.
• Temporal Bones:
  • One plate on either side of the skull.
  • Contains the zygomatic process (which forms part of the zygomatic arch).
• Occipital Bone:
  • One plate forming the base of the skull.
• Sphenoid Bone:
  • A complex, butterfly-shaped bone forming part of the base and sides of the skull.
  • Features include pterygoid processes, lateral pterygoid plate, and medial pterygoid plate.

Facial Bones

• Nasal Bones:
  • Two bones joined together centrally.
  • Connect to the frontal bone above to form the bridge of the nose.
• Zygomatic Bones (Zygoma):
  • These are the cheekbones.
  • Connect with the temporal bone to form the zygomatic arch.
• Maxilla:
  • The upper jaw bone.
  • Palatal Aspect: Contains the incisive foramen and greater palatine foramen.
• Mandible:
  • The lower jaw bone, the only movable bone of the skull.
  • **Detailed Anatomy (Referencing figures on slides 35, 37, 38, 40, 41):
    1. Coronoid Process: An anterior superior projection of the ramus.
    2. Sigmoid Notch (Mandibular Notch): The concavity between the coronoid process and the condyle.
    3. Condyle (Condylar Process): The posterior superior projection of the ramus, articulating with the temporal bone at the temporomandibular joint (TMJ).
    4. Mandibular Foramen: An opening on the inner (medial) surface of the ramus, through which nerves and blood vessels enter the mandible.
    5. Lingula: A small tongue-shaped projection of bone located on the inner surface of the ramus, anterior to the mandibular foramen.
    6. Mylohyoid Line: A ridge on the inner surface of the body of the mandible, serving as the origin for the mylohyoid muscle.
    7. Alveolar Process (Inner Aspect): The bone supporting the teeth on the lingual side.
    8. Alveolar Process (Outer Aspect): The bone supporting the teeth on the buccal/labial side.
    9. Mental Protuberance (Chin): The prominent bony projection forming the chin.
    10. Mental Foramen: An opening on the outer (lateral) surface of the body of the mandible, usually below the premolars, allowing passage of the mental nerve and vessels.
    11. External Oblique Line: A ridge on the outer surface of the body of the mandible, extending from the ramus.
    12. Ramus: The vertical part of the mandible, extending upwards from the body.
    13. Body: The horizontal part of the mandible, which houses the teeth.
    14. Angle: The junction between the body and the ramus of the mandible.
  • Other noted features:
    • Submandibular fossa: Depression on the inner surface for the submandibular gland.
    • Sublingual fossa: Depression on the inner surface for the sublingual gland.

Muscles of Mastication

• General Role: These four pairs of muscles connect the cranium to the mandible and are primarily responsible for closing the mouth and performing chewing movements.
• Key Facts Needed for Each Muscle: Origin, Insertion, and Actions.

The Four Pairs of Muscles of Mastication

1. Masseter Muscle:
   • Shape: Chunky, quadrangular shape.
   • Point of Origin: Outer surface of the zygomatic arch.
   • Point of Insertion: Outer surface of the ramus and angle of the mandible.
   • Action: Closes the mouth (elevates the mandible).
   • Can be felt by clenching and releasing teeth.
2. Temporalis Muscle:
   • Shape: Fan-shaped.
   • Point of Origin: Temporal bone of the cranium.
   • Point of Insertion: Coronoid process of the mandible, passing under the zygomatic arch.
   • Action: Pulls the mandible backwards to close the mouth (retracts and elevates the mandible).
   • Considered one of the strongest muscles of mastication.
3. Medial Pterygoid Muscle:
   • Shape: Replica of the masseter muscle (similar in function and position, but internally).
   • Point of Origin: Medial pterygoid plate of the sphenoid bone.
   • Point of Insertion: Inner surface of the ramus and angle of the mandible.
   • Action: Closes the mouth (elevates the mandible, aids in protrusion).
4. Lateral Pterygoid Muscle:
   • Shape: Conical shaped muscle.
   • Point of Origin: Base of the cranium, specifically the lateral pterygoid plate of the sphenoid bone (superior head and inferior head).
   • Point of Insertion: Head of the condyle of the mandible and into the temporomandibular joint (TMJ).
   • Action:
     • Pulls the mandible forward (protrusion).
     • Allows for incisal edge-to-edge biting.
     • Swings the mandible from side to side (lateral excursion).

Muscles of Facial Expression

• General Role: These muscles lie within the soft tissues of the face, allowing us to display various expressions.

Categories of Facial Expression Muscles

1. Muscles of the Eye:
   • Orbicularis Oculi:
     • Encircles the eye.
     • Responsible for closing the eyelids, winking, and squinting.
2. Muscles Around the Mouth:
   • Orbicularis Oris:
     • Encircles the mouth, forming an