Lecture on Oral Anatomy & Histology

Oral Anatomy & Histology - DENT 237 Study Notes

Course Information

Course Title: Oral Anatomy & Histology - DENT 237
Outcome: 12
Date: 11/19/2025

Important Reminders

Oral Pathology Assignment: Due TOMORROW - Friday, November 21 at 11:59 PM (20% of final grade)
Oral Pathology Presentations: Thursday, November 27 during your D237 lab session
Final Exam: Monday, December 8 at 8:00 AM (35% of final grade)

Blood Supply to the Head and Neck

Significance: Understanding the blood supply is crucial as these vessels may become compromised by diseases or during dental procedures like administering local anesthetics (Bird & Robinson, 2021).

Major Arteries of the Face and Oral Cavity

Common Carotid Artery:
- Origin: Arises from the aorta.
- Subdivisions: Divides into the internal and external carotid arteries.
Internal Carotid Artery:
- Function: Supplies blood to the brain and eyes.
External Carotid Artery:
- Function: Provides the main blood supply to the face and mouth (Bird & Robinson, 2021).

Branches of the External Carotid Artery

Facial Artery:
- Branches: 6 branches supplying various structures:
  - Pharyngeal muscles
  - Soft palate
  - Tonsils
  - Posterior tongue
  - Submandibular gland
  - Muscles of the face
  - Nasal septum
  - Nose and eyelids.
Lingual Artery:
- Branches: Supplies the tongue, floor of the mouth, lingual gingiva, a portion of the soft palate, and tonsils.
Maxillary Artery:
- Divisions: Divides into the inferior alveolar artery, pterygoid artery, and pterygopalatine artery.

Blood Supply to Structures of the Face and Oral Cavity

Muscles of facial expression: Supplied by branches from maxillary, facial, and ophthalmic arteries.
Maxillary Bones: Supplied by anterior, middle, and posterior alveolar arteries.
Maxillary Teeth: Supplied by anterior, middle, and posterior alveolar arteries.
Mandible: Supplied by inferior alveolar arteries.
Mandibular Teeth: Supplied by inferior alveolar arteries.
Tongue: Supplied by lingual artery.
Muscles of mastication: Supplied by facial arteries.

Major Veins of the Face and Oral Cavity

Maxillary vein
Retromandibular vein
External jugular vein
Subclavian vein
Facial vein
Common facial vein
Deep facial vein
Lingual veins
Internal jugular vein (Bird & Robinson, 2021).

Learning Checks

Common Carotid Artery:
- Arises from the aorta and subdivides into the internal and external carotid arteries.
Internal Carotid Artery: Supplies blood to the brain and eyes.
External Carotid Artery: Provides blood to the face and mouth.

Nervous System Overview

Importance: Understanding the nerves of the head and neck is critical for administering local anesthesia during dental treatments and understanding conditions like facial paralysis (Bird & Robinson, 2021).
Components:
- Central Nervous System (CNS):
  - Brain
  - Spinal cord
- Peripheral Nervous System (PNS):
  - Autonomic nervous system (ANS):
  - Sympathetic
  - Parasympathetic
  - Somatic nervous system

Cranial Nerves

Cranial Nerves Overview:
- There are 12 pairs of cranial nerves, connected to the brain.
- Serve both sensory and motor functions.
- Named for the area or function served and are identified with Roman numerals (Bird & Robinson, 2021).

Trigeminal Nerve (Cranial Nerve V)

Roles: Primarily responsible for the innervation of the oral cavity (Bird & Robinson, 2021).
Divisions:
1. Ophthalmic Division (V1)
2. Maxillary Division (V2)
  - Supplies: Maxillary teeth, periosteum, mucous membrane, maxillary sinuses, and soft palate.
  - Subdivides into:
    - Nasopalatine nerve
    - Greater palatine nerve
    - Anterior superior alveolar nerve
    - Middle superior alveolar nerve
    - Posterior superior alveolar nerve.
3. Mandibular Division (V3)
  - Components:
    - Buccal Nerve: Supplies mucous membrane and mucoperiosteum of the mandibular molar teeth.
    - Lingual Nerve: Supplies anterior two-thirds of the tongue, lingual mucous membrane, and mucoperiosteum.
    - Inferior Alveolar Nerve:
    - Further subdivides into:
      - Mylohyoid nerve: Supplies mylohyoid muscles and the anterior belly of the digastric muscle.
      - Small dental nerves: Supply molar and premolar teeth, alveolar process, and periosteum.
      - Mental nerve: Passes through mental foramen, supplying the chin and lower lip mucous membrane.
      - Incisive nerve: Continues anteriorly, supplying incisor teeth (Bird & Robinson, 2021).

Injection Techniques in Dentistry

Maxillary vs. Mandibular Anesthesia:
- Maxillary injections differ from mandibular due to the porous nature of alveolar cancellous bone in the maxilla, allowing diffusing anesthetic solutions compared to denser mandibular bone (Bird & Robinson, 2021).

Types of Anesthesia Techniques

Local Infiltration: Injection into a small, isolated area.
Field Block: Injection of anesthetic near a larger terminal nerve branch.
Nerve Block: Local anesthetic deposited close to a main nerve trunk (Bird & Robinson, 2021).

Maxillary Injections

Types:
- Posterior Superior Alveolar: Targeting maxillary 2nd & 3rd molars, distobuccal and lingual roots of the 1st molar, surrounding buccal gingiva.
- Middle Superior Alveolar: Targeting maxillary 1st & 2nd premolars, mesiobuccal root of the 1st molar, surrounding gingiva.
- Anterior Superior Alveolar: Targeting maxillary central, lateral, and cuspid teeth, and surrounding buccal gingiva (Bird & Robinson, 2021).

Palatal Anesthesia

Applications: For procedures involving soft tissues of the palate.
- Greater Palatine Nerve: Passes through posterior palatine foramen, innervating mucosa of the hard palate (except lingual to maxillary incisors).
- Nasopalatine Nerve: Passes through the incisive foramen, innervating gingiva palatal to maxillary anterior teeth (Bird & Robinson, 2021).

Mandibular Anesthesia

Characteristics: Due to the dense nature of mandibular bone, anesthetic does not diffuse easily, often requiring block anesthesia.
- Injection techniques include:
- Inferior Alveolar Nerve Block: Targets the entire area served by the nerve branch.
- Buccal Nerve Block: For buccal mucous membranes.
- Incisive Nerve Block: Targets incisor teeth area (Bird & Robinson, 2021).

Supplemental Injection Techniques

Periodontal Ligament Injection: Injection of anesthetics directly into the periodontal ligament and surrounding tissues under pressure.
Other Techniques:
- Intraosseous Injection
- Gow-Gates Mandibular Block
- Vazirani-Akinosi Mandibular Block (Bird & Robinson, 2021).

Review Questions

Which artery supplies blood to the face and mouth?
a) Internal carotid
b) External carotid
c) Aorta
d) Jugular
Which artery supplies blood to the maxillary anterior teeth?
a) Anterior superior alveolar
b) Lingual
c) Facial
d) Posterior superior alveolar
The oral cavity is primarily innervated by which of the following nerves?
a) Buccal
b) Anterior superior palatine
c) Trigeminal
d) Nasopalatine
Which nerve innervates the maxillary first and second premolars?
a) Mylohyoid
b) Middle superior alveolar
c) Mental
d) Anterior superior alveolar
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
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
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
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