Study Notes on Oral Anatomy & Histology for DENT 237

Blood Supply to the Head and Neck

  • Crucial for dental procedures (e.g., local anesthetics) and understanding disease.

  • Common Carotid Artery: Originates from the aorta, divides into:

    • Internal Carotid Artery: Supplies brain and eyes.

    • External Carotid Artery: Major blood supply to the face and mouth.

Branches of the External Carotid Artery

  • Facial Artery: Supplies pharyngeal muscles, soft palate, tonsils, posterior tongue, submandibular gland, face muscles, nasal septum, nose, and eyelids.

  • Lingual Artery: Supplies tongue, floor of mouth, lingual gingiva, and part of soft palate and tonsils.

  • Maxillary Artery: Divides into inferior alveolar, pterygoid, and pterygopalatine arteries.

Summary of Major Arteries Supplying Structures

  • Muscles of Facial Expression: Maxillary, facial, ophthalmic arteries.

  • Maxillary Bones & Teeth: Anterior, middle, posterior alveolar arteries.

  • Mandible & Mandibular Teeth: Inferior alveolar arteries.

  • Tongue: Lingual artery.

  • Muscles of Mastication: Facial arteries.

Major Veins of the Face and Oral Cavity

  • Maxillary, Retromandibular, External Jugular, Subclavian, Facial, Common Facial, Deep Facial, Lingual, Internal Jugular veins.

Overview of the Nervous System

  • Essential for local anesthesia in dentistry and understanding conditions like facial paralysis.

Components of the Nervous System

  • Central Nervous System: Brain and spinal cord.

  • Peripheral Nervous System: Autonomic (Sympathetic, Parasympathetic) and Somatic Nervous System.

Cranial Nerves

  • 12 pairs, perform both sensory and motor functions, named by area/function and Roman numerals.

Trigeminal Nerve (Cranial Nerve V)

  • Primary innervation for the oral cavity.

  • Divisions: 1. Ophthalmic (V1), 2. Maxillary (V2), 3. Mandibular (V3).

Maxillary Division (V2)

  • Supplies maxillary teeth, periosteum, mucous membrane, sinuses, and soft palate.

  • Branches:

    • Nasopalatine nerve: Innervates mucoperiosteum palatal to maxillary anterior teeth (via incisive foramen).

    • Greater palatine nerve: Innervates hard palate mucoperiosteum (via posterior palatine foramen).

    • Anterior superior alveolar nerve: Supplies maxillary central, lateral, cuspid teeth, their periodontal structures, and maxillary sinus.

    • Middle superior alveolar nerve: Supplies maxillary first and second premolars, mesiobuccal root of the first molar, and maxillary sinus.

Posterior Superior Alveolar Nerve (PSA)

  • Supplies other roots of maxillary first molar, maxillary second and third molars, and lateral wall of maxillary sinus.

Mandibular Division of the Trigeminal Nerve

  • Branches:

    • Buccal Nerve: Supplies buccal mucous membrane and mucoperiosteum of mandibular molars.

    • Lingual Nerve: Supplies anterior two-thirds of the tongue, lingual mucous membrane and mucoperiosteum.

    • Inferior Alveolar Nerve: Subdivides into:

    1. Mylohyoid nerve: Supplies mylohyoid and anterior digastric muscles.

    2. Small dental nerves: Supply molar and premolar teeth, alveolar process, and periosteum.

    3. Mental nerve: Supplies chin and lower lip mucous membrane (exits mental foramen).

    4. Incisive nerve: Supplies incisor teeth.

Nerves of Facial Expression

  • Facial Nerve (Cranial Nerve VII): Mixed nerve (sensory for taste, motor for facial expression, tears, saliva). Damage can cause sagging facial muscles and taste distortion.

Injection Techniques Overview

  • Anesthetic placement and type depend on tooth location and innervation (Maxillary, Palatal, Mandibular anesthesia).

Maxillary Anesthesia

  • Anesthetic diffuses easily due to porous maxillary alveolar bone.

Types of Anesthesia Techniques for Maxilla

  • Local infiltration: For small, isolated areas.

  • Field block: Near a larger terminal nerve branch.

  • Nerve block: Close to a main nerve trunk.

Maxillary Nerves

  • Posterior Superior Alveolar: Maxillary 2nd and 3rd molars, distobuccal and lingual roots of the 1st molar, surrounding buccal gingiva.

  • Middle Superior Alveolar: Maxillary 1st and 2nd premolars, mesiobuccal root of the 1st molar, surrounding buccal gingiva.

  • Anterior Superior Alveolar: Maxillary central, lateral, and cuspid teeth, surrounding buccal gingiva.

Palatal Anesthesia

  • Important for palatal soft tissue procedures.

  • Nerves:

    • Greater Palatine Nerve: Innervates hard palate mucosa (except lingual to maxillary incisors) via posterior palatine foramen.

    • Nasopalatine Nerve: Innervates gingiva palatal to maxillary anterior teeth via incisive foramen.

Mandibular Anesthesia

  • Challenging due to dense mandibular bone, leading to poor anesthetic diffusion.

  • Common Practices: Block anesthesia (injecting near major nerves).

  • Techniques: Inferior alveolar nerve block, Buccal nerve block, Incisive nerve block.

Supplemental Injection Techniques

  • Methods:

    • Periodontal Ligament Injection (PDL): Anesthetic injected under pressure into periodontal ligament, adjunct to conventional methods.

    • Intraosseous Injection.

    • Gow-Gates Mandibular Block.

    • Vazirani-Akinosi Mandibular Block.

Review Questions

  1. Which artery supplies blood to the face and mouth?

    a) Internal carotid

    b) External carotid

    c) Aorta

    d) Jugular

  2. Which artery supplies blood to the maxillary anterior teeth?

    a) Anterior superior alveolar

    b) Lingual

    c) Facial

    d) Posterior superior alveolar

  3. The oral cavity is primarily innervated by which of the following nerves?

    a) Buccal

    b) Anterior superior palatine

    c) Trigeminal

    d) Nasopalatine

  4. Which nerve innervates the maxillary first and second premolars?

    a) Mylohyoid

    b) Middle superior alveolar

    c) Mental

    d) Anterior superior alveolar

  5. Which of the following arteries supplies the maxillary posterior teeth?

    a) Posterior superior alveolar artery

    b) Lingual artery

    c) Inferior alveolar artery

    d) Facial artery

  6. If a patient has permanent paralysis of the tongue and lip after the extraction of a mandibular third molar, which cranial nerve was damaged?

    a) IV – trochlear

    b) VII – facial

    c) V – trigeminal

    d) VI – abducens

  7. The trigeminal nerve subdivides into 3 main divisions which are the:

    a) Ophthalmic division, maxillary division, mandibular division

    b) Ocular, nasopalatine, anterior superior alveolar

    c) Anterior superior alveolar, middle superior alveolar, posterior superior alveolar

    d) Mental, incisive, buccal nerve

  8. A nerve block occurs:

    a) By injecting into a small, isolated area

    b) By an injection of anesthetic near a larger terminal nerve branch

    c) When local anesthetic is deposited close to a main nerve trunk

    d) When the patient experiences prolonged numbness in the tongue.

References

  • Bird, D.L & Robinson, D.S. (2021). Modern dental assisting (13th ed.). Elsevier.