4: Head, Neck, and Dental Anatomy

Chapter 4 Head, Neck, and Dental Anatomy

REGIONS OF THE HEAD

Regions of the head include frontal, parietal, occipital, temporal, orbital, nasal, infraorbital, zygomatic, buccal, oral, mental regions. Specific landmarks are noted for each region.

Oral Cavity

Oral cavity is the inside of the mouth and includes jaws, palate, tongue, floor of the mouth, pharynx, and all associated oral mucosal tissues.

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Figure 4-1 Tongue and tonsillar tissues.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-2 Floor of the mouth.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

SKULL

Skeletal system serves as a base during palpation of soft tissues and as a marker during location of soft tissue lesions, administration of local anesthesia, radiographic procedures. Bones may be a factor in spread of dental infection and may undergo a disease process themselves.

Skull (22 bones), with single and paired bones. Immovable, with EXCEPTION of mandible and temporomandibular joint (TMJ). Has movable articulation with bony vertebral column in neck area. Contains bony openings for important nerves and blood vessels (Table 4-1). Has paranasal sinuses within that serve to lighten bony mass. Has many associated processes that are involved in important structures. To study its landmarks, important to view from superior, lateral, inferior, anterior. Its bones are divided into three categories: cranial, facial, hyoid, which are noted on each view; each category is discussed separately next.

Table 4-1 Bony openings in the skull and their associated nerves and blood vessels

Bony opening Bony location Nerves and vessels
Carotid canal Temporal Internal carotid artery
Cribriform plate with foramina Ethmoid Olfactory nerves
External acoustic meatus Temporal (Opening to tympanic cavity)
Foramen lacerum Sphenoid, occipital, temporal (Cartilage)
Foramen magnum Occipital Spinal cord, vertebral arteries, eleventh cranial nerve
Foramen ovale Sphenoid Mandibular division of fifth cranial nerve
Foramen rotundum Sphenoid Fifth cranial nerve
Foramen spinosum Sphenoid Middle meningeal artery
Greater palatine foramen Palatine Greater palatine nerve and vessels
Hypoglossal canal Occipital Ninth cranial nerve
Incisive foramen Maxilla Nasopalatine nerve and branches of sphenopalatine artery
Inferior orbital fissure Sphenoid and maxilla Infraorbital and zygomatic nerves, infraorbital artery, ophthalmic vein
Infraorbital foramen and canal Maxilla Infraorbital nerve and vessels
Internal acoustic meatus Temporal Seventh and eighth cranial nerves
Jugular foramen Occipital and temporal Internal jugular vein and ninth, tenth, eleventh cranial nerves
Lesser palatine foramen Palatine Lesser palatine nerve and vessels
Mandibular foramen Mandible Inferior alveolar nerve and vessels
Mental foramen Mandible Mental nerve and vessels
Optic canal and foramen Sphenoid Optic nerve and ophthalmic artery
Petrotympanic fissure Temporal Chorda tympani nerve
Pterygoid canal Sphenoid Area nerves and vessels
Stylomastoid foramen Temporal Seventh cranial nerve
Superior orbital fissure Sphenoid Third, fourth, sixth cranial nerves and ophthalmic nerve and vein

From Fehrenbach MJ, Herring SW: Illustrated anatomy of the head and neck, ed 3, St. Louis, 2007, Saunders/Elsevier.

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Figure 4-4 Anterior view of skull.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-5 Lateral view of skull.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-6 Inferior view of external surface of skull.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-7 Inferior view of hard palate.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-8 Superior view of internal surface of skull.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

Cranial Bones

Cranial bones (8) form cranium and include occipital, frontal, parietal, temporal, sphenoid, ethmoid. See earlier views of skull.

Facial Bones

Facial bones (14) create facial features and serve as base for the dentition. Include vomer, lacrimal, zygomatic, palatine, maxilla, mandible. See earlier skull views. Many landmarks of the facial bones are used for local anesthetic delivery.

E. Maxilla: upper jaw, consists of two maxillary bones (maxillae) fused together; articulates with frontal, lacrimal, nasal, inferior nasal concha, sphenoid, ethmoid, palatine, zygomatic bones, vomer (Figure 4-9); each maxilla has a body and frontal, zygomatic, palatine, alveolar processes:

F. Mandible: lower jaw, single, ONLY freely movable bone of skull; articulates with temporal bones at each TMJ (Figure 4-10):

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Figure 4-9 Maxilla.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-10 Mandible.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

MUSCLES OF FACIAL EXPRESSION

Muscles of facial expression act in various combinations to alter appearance of face; innervated by the facial nerve, seventh (VII) cranial nerve (Figure 4-11).

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Figure 4-11 Muscles of facial expression.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

Muscles of Mastication

Muscles of mastication are paired muscles that attach to mandible and work with TMJ to accomplish movements of mandible: depression, elevation, protrusion, retraction, lateral deviation (Figures 4-12 and 4-13). Innervated by mandibular division of fifth (V) cranial nerve (trigeminal). Include masseter, temporalis, medial pterygoid, lateral pterygoid. Involved in temporomandibular joint disorder (TMD). See later discussion on occlusion in regard to masseter.

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Figure 4-12 Muscles of mastication.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-13 Muscles of mastication.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

Hyoid Muscles

Hyoid muscles are located superficially in neck tissues, attached to hyoid. Assist in the actions of mastication and swallowing (Figure 4-14).

A. Suprahyoids: paired that are located superior to hyoid:

3. Categorized according to anterior or posterior position relative to hyoid:

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Figure 4-14 Hyoid muscles.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

TEMPOROMANDIBULAR JOINT

Temporomandibular joint (TMJ) is located on each side of the head and allows movement of the mandible for speech and mastication (Figure 4-15). Innervated by mandibular division of fifth cranial nerve (trigeminal) and blood supply from the external carotid artery. Patients may experience a temporomandibular joint disorder (TMD) of one or BOTH of these joints. Bones of the TMJ are discussed in skeletal system section.

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Figure 4-15 Temporomandibular joint.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

CLINICAL STUDY

Age 58 YRS SCENARIO
Sex image Male image Female The first afternoon patient has not had a dental examination since her last dentist retired 2 years ago. An initial extraoral examination indicates that her zygomatic region is fi rm and enlarged; she currently has no pain or discomfort in the jaw area. She does admit to frequently grinding her teeth at night.
Height 5′6″
Weight 75 LBS
BP 115/68
Chief Complaint “My jaws really ache when I wake up.”
Medical History

Current Medications

Social History

ARTERIAL BLOOD SUPPLY OF THE HEAD AND NECK

MAJOR arteries that supply the head and neck are the subclavian and the common carotid. Their paths from the heart to the head and neck are different, depending on side of the body; other arteries of the head and neck are symmetrically located on each side of body. Vascular system supplies tissues with nutrients. May become compromised by disease process or during dental procedure.

D. External carotid:

6. Terminal branches of external carotid:

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Figure 4-16 Maxillary artery.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

VENOUS DRAINAGE OF THE HEAD AND NECK

Veins are symmetrically located but have greater variability in location than do arteries. Veins anastomose freely and generally are larger and MORE numerous than arteries in same tissue. Internal jugular drains brain and other tissue; external jugular drains only some extracranial tissues, with many anastomoses between them. Internal and external jugular are major venous drainage vessels of head and neck (Figure 4-17). Leaving the head near the base of neck, veins become larger. Vascular system is capable of spreading infection or cancerous cells in head and neck area because valveless veins control direction of blood flow.

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Figure 4-17 Venous drainage of head and neck.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

GLANDULAR TISSUE

Glandular tissues include the lacrimal, salivary, thyroid, parathyroid, thymus glands.

B. Salivary glands (Figure 4-18):

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Figure 4-18 Salivary glands.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

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Figure 4-19 Thyroid and parathyroid glands.

(From Fehrenbach MJ, ed: Dental anatomy coloring book, St. Louis, 2008, Saunders/Elsevier.)

CLINICAL STUDY

Age 49 YRS SCENARIO
Sex image Male image Female The intraoral examination of the patient reveals a number of carious lesions, and the oral mucosa appears quite dry.
Height 6′5″
Weight 175 LBS
BP 112/62
Chief Complaint “My mouth is so sore when I eat!”
Medical History Recent radiation therapy for low-grade adenoid cystic carcinoma of the submandibular gland after surgical removal
Current Medications None
Social History

TRIGEMINAL NERVE AND SENSORY ROOT

Trigeminal nerve (fifth cranial nerve [V]) is formed by ophthalmic, maxillary, mandibular branches.

B. Maxillary division (maxillary nerve, V2) of fifth cranial nerve (trigeminal) (Figure 4-20):

C. Mandibular division (mandibular nerve, V3) of fifth cranial nerve (trigeminal) (Figure 4-21):

Jan 1, 2015 | Posted by in Dental Hygiene | Comments Off on 4: Head, Neck, and Dental Anatomy
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