Applied Orofacial Anatomy

Question 1

Which five bones make up the nose?

Answer 1

1. Maxilla: frontal process of maxilla
2. Frontal bone: nasal process of frontal bone
3. Nasal bones
4. Vomer: contributes to the septum
5. Ethmoid: perpendicular plate of the ethmoid also contributes to the septum

Question 2

What is the vascular supply to the nose?

Answer 2

Branches from both the external and internal carotid arteries supply the nose. The external nose is
supplied by the dorsal nasal of the ophthalmic artery superiorly, and the septal and lateral nasal of the
angular artery inferiorly. The lower part of the dorsum of the nose is supplied by the external nasal,
from the anterior ethmoidal artery.
The external carotid artery via the terminal branches of the internal maxillary artery, namely the
sphenopalatine and greater palatine arteries, supplies the posterior inferior part of the internal nose.
Branches from the anterior and posterior ethmoid arteries of the ophthalmic artery supply the anterior
inferior nasal cavity, which is a branch of the internal carotid artery. Venous drainage of the nose
corresponds to the arterial nomenclature and occurs through the sphenopalatine, ophthalmic, and
anterior facial veins.

Question 3

How is the sensory nerve supply to the nose mapped?

Answer 3

• Olfactory fibers are located in the superior portion of the internal nose and serve the sensory function of smell.
• The sensory innervation of the skin of the root of the nose is derived from the supratrochlear and
infratrochlear branches of the ophthalmic nerve.
• Branches of the infraorbital nerve supply the skin on the lower half of the nose’s side.
• Nasociliary branches of the ophthalmic nerve supply the skin over the lower dorsum of the nose
down to the tip.
• The trigeminal nerve supplies general sensory innervation to the anterior internal nose through the
anterior ethmoidal, external, and internal nasal branches.
• The lateral posterior superior, pharyngeal, and lateral posterior inferior branches of the maxillary
nerve supply the posterior portion.
• The terminal branches of the infraorbital nerve supply the lining of the nasal vestibule.
• The internal nasal (anterior ethmoidal) and medial posterior superior branches supply the septum
anterior and posterior portions, respectively.

Question 4

Where do the paranasal sinuses drain?

Answer 4

The sphenoid sinus drains into the sphenoethmoidal recess. The posterior ethmoid sinus drains into
the superior nasal meatus, and the nasolacrimal duct drains into the inferior nasal meatus. All other
sinuses (maxillary, frontal, and anterior and middle ethmoidal) drain into the middle nasal meatus.

Question 5

What other nerves supply the ear?

Answer 5

The auriculotemporal nerve (CN V3) supplies the root helix, crus, tragus, and canal, whereas the
auricular branch off the facial nerve (CN VII) supplies the concha and canal. Thus, in all, four cranial
nerves (V, VII, IX, and X) provide sensory innervation for the ear.

Question 6

What is the sensory innervation to the larynx?

Answer 6

The vagus nerve innervates the larynx via two laryngeal branches, the internal laryngeal and the
recurrent laryngeal. The internal laryngeal branch provides sensory innervation to the mucous membrane above the vocal fold, whereas the recurrent laryngeal nerve provides sensory innervation to the
mucous membrane below the vocal fold.
Motor function of the laryngeal muscles and vocal cords also is provided by the laryngeal
branches of the vagus nerve (fibers of CN XI traveling with CN X). The external laryngeal branch
innervates the cricothyroid muscle, and the recurrent laryngeal branch innervates all other intrinsic
muscles.

Question 7

Which bones form the orbital cavity?

Answer 7

• Lacrimal
• Sphenoid
• Ethmoid
• Zygomatic
• Palatine
• Maxillary
• Frontal

Question 8

What are the functions of the extraocular muscles?

Answer 8

• Lateral rectus muscle: abduction
• Medial rectus muscle: adduction
• Inferior rectus muscle: depression, adduction, and extorsion (extorsion—the superior pole of the
globe moves laterally)
• Superior rectus muscle: elevation, adduction, and intorsion (intorsion—the superior pole of the
globe moves medially)
• Superior oblique muscle: depression, abduction, and intorsion
• Inferior oblique muscle: elevation, abduction, and extorsion

Question 9

Which bony structures surround the orbit and protect its contents?

Answer 9

• Superiorly: The supraorbital rim is formed by the supraorbital arch of the frontal bone.
• Inferiorly: The thick infraorbital rim is formed by the zygoma laterally and the maxilla medially.
• Medially: The nasal spine of the frontal bone and the frontal process of the maxilla constitute the
anteromedial orbital wall.
• Laterally: The frontal process of the zygoma and the zygomatic process of the frontal bone constitute the lateral orbital rim.

Question 10

How many bones form the orbit? Which bones?

Answer 10

Seven bones form the orbit.
The roof is composed mainly of the orbital plate of the frontal bone. Posteriorly it receives a
minor contribution from the lesser wing of the sphenoid.
The orbital floor is composed of the orbital plate of the maxilla, the zygomatic bone anterolaterally, and the orbital process of the palatine bone posteriorly. The orbital floor is equivalent to the roof
of the maxillary sinus.
The lateral wall is formed primarily by the orbital surface of the zygomatic bone and the greater
wing of the sphenoid bone. The sphenoid portion of the lateral wall is separated from the roof by the
superior orbital fissure and from the floor by the inferior orbital fissure.
The medial wall is quadrangular in shape and composed of four bones: (1) the ethmoid bone
centrally; (2) the frontal bone superoanteriorly; (3) the lacrimal bone inferoanteriorly; and (4) the sphenoid bone posteriorly. The medial wall is made of a very thin plate, with the largest component being
the ethmoidal portion, which is called the lamina papyracea (paperlike).

Question 11

Which is the only bone that exists entirely within the orbital confines?

Answer 11

lacrimal bone.

Question 12

Which bone is the keystone of the orbit?

Answer 12

The sphenoid bone. All neurovascular structures to the orbit pass through this bone

Question 13

What structures pass through the inferior orbital fissure?

Answer 13

The inferior orbital fissure, which separates the greater sphenoid wing portion of the lateral wall from
the floor, permits passage of (1) the maxillary division of the trigeminal nerve (CN V2) and its branches
(including the infraorbital nerve); (2) the infraorbital artery; (3) branches of the sphenopalatine ganglion; and (4) branches of the inferior ophthalmic vein to the pterygoid plexus.

Question 14

What is the blood supply to the temporalis muscle and the temporalis fascia?

Answer 14

The muscle is supplied primarily by the anterior and posterior deep temporal arteries (branches of the
internal maxillary artery) and to a lesser extent by the superficial temporal artery.
The middle temporal artery, a branch of the superficial temporal artery, is the main supply to the fascia.

Question 15

What is the blood supply to the temporal fat pad?

Answer 15

The blood supply to the temporal fat pad is from the middle temporal artery, which is a branch of the
superficial temporal artery.

Question 16

Olfactory nerve (I) component and function

Answer 16

Sensory and smell

Question 17

Olfactory nerve (I) skull opening

Answer 17

Opening in cribriform
plate of ethmoid

Question 18

Optic nerve (II) component and function

Answer 18

Sensory and vision

Question 19

Optic nerve (II) skull opening

Answer 19

Optic canal

Question 20

Oculomotor nerve (III) component and function

Answer 20

Motor

Lifts upper eyelid; turns eyeball
upward, downward, and
medially; constricts pupil;
accommodates eye

Question 21

Oculomotor nerve (III) skull opening

Answer 21

Superior orbital fissure

Question 22

Trochlear nerve (IV) component and function

Answer 22

Motor

Assists in turning eyeball downward and laterally

Question 23

Trochlear nerve (IV) skull opening

Answer 23

Superior orbital fissure

Question 24

Opthalmic division of trigeminal nerve (V1) component and function

Answer 24

Sensory

Cornea, skin of forehead, scalp,
eyelids, and nose; also mucous membrane of paranasal
sinuses and nasal cavity

Question 25

Opthalmic division of trigeminal nerve (V1) skull opening

Answer 25

Superior orbital fissure

Question 26

Maxillary division of trigeminal nerve (V2) component and function

Answer 26

Sensory Skin of face over maxilla and the upper lip; teeth of upper jaw; mucous membrane of nose, the maxillary air sinus, and palate

Question 27

Maxillary division of trigeminal nerve (V2) skull opening

Answer 27

Foramen rotundum

Question 28

Mandibular division of trigeminal nerve (V3) component and function

Answer 28

Motor. Muscles of mastication, mylohyoid, anterior belly of digastric, tensor veli palatini, and tensor tympani Sensory. Skin of cheek, skin over mandible, lower lip, and side of head; teeth of lower jaw and temporomandibular joint; mucous membrane of mouth and anterior two-thirds of tongue

Question 29

Mandibular division of trigeminal nerve (V3) skull opening

Answer 29

Foramen ovale

Question 30

Facial nerve (VII) motor component function

Answer 30

Muscles of face, the cheek, and scalp; stapedius muscle of middle ear; stylohyoid; posterior belly of digastric

Question 31

Facial nerve (VII) sensory component function

Answer 31

Taste from anterior two-thirds of tongue; floor of mouth and palate

Question 32

Facial nerve (VII) secretomotor parasympathetic component function

Answer 32

Submandibular and sublingual salivary glands, the lacrimal gland, and glands of nose and palate

Question 33

Facial nerve (VII) skull opening

Answer 33

Internal acoustic meatus, facial canal, stylomastoid foramen

Question 34

Glossopharyngeal nerve (IX) Secretomotor parasympathetic component function

Answer 34

Parotid salivary gland

Question 35

Glossopharyngeal nerve (IX) sensory component function

Answer 35

General sensation and taste from posterior third of tongue and pharynx; carotid sinus and carotid body

Question 36

Glossopharyngeal nerve (IX) skull opening

Answer 36

Jugular foramen

Question 37

Hypoglossal nerve (XII) component and function

Answer 37

Motor Muscles of tongue controlling its shape and movement (except palatoglossus)

Question 38

Hypoglossal nerve (XII) skull opening

Answer 38

Hypoglossal canal

Question 39

What is the danger zone for the marginal mandibular branch of the facial nerve?

Answer 39

The mandibular branch of the facial nerve courses in an area where incisions to approach the mandible and mandibular condyle are commonly placed. Accordingly, this area is considered a danger zone for injury to this branch. The zone is located between the inferior border of the mandible and a line in the retromandibular and submandibular region. This line extends from anterior to posterior and is 2 cm (1 thumb-breadth) behind the gonion and posterior border of the ascending ramus, 2 cm below the gonion, extending forward 2 cm below the inferior border of the mandible as far anteriorly to the level of the second premolar tooth. The anterior border of the zone is located at the intersection of two lines: a horizontal line 2 cm below and parallel to the inferior border of the body of the mandible, and another along the long axis of the lower second premolar.

Question 40

What are the branches of the facial nerve?

Answer 40

The facial nerve trunk has six major branches: temporal, zygomatic, buccal, mandibular, cervical, and auricular. The auricular branch comes off before the facial nerve turns into the parotid body, and innervates the superior auricular, posterior auricular, and occipitalis muscles, as well as provides sensation to the area behind the earlobe. Within the parotid, the facial nerve divides into two main branches, the temporofacial and cervicofacial, which further divide into the temporal, zygomatic, buccal, mandibular, and cervical branches. The stylohyoid and posterior digastric are other minor branches of the nerve.

Question 41

How do the facial muscles of expression receive their innervation?

Answer 41

All facial muscles except the mentalis, levator angularis superioris, and buccinator receive their innervation along their deep surfaces. However, because these three muscles are located deep within the facial soft tissue and lie deep to the plane of the facial nerve, they receive their innervation along their superficial surfaces. All other facial muscles of expression are located superficial to the plane of the facial nerve and thus receive their innervation along their deep or posterior surfaces. For example, the platysma, orbicularis oculi, and zygomaticus major and minor are situated superficial to the level of the facial nerve.

Question 42

How do you evaluate the five branches of the facial nerve during a physical exam?

Answer 42

Test each of the five branches of the nerve in the following manner: • Cervical: Contract the platysma muscles. • Marginal mandibular: Whistle or pucker the lips. • Buccal: Smile or show teeth. • Zygomatic: Squeeze eyes shut tightly. • Temporal: Raise eyebrows.

Question 43

What are the most common causes of facial nerve paralysis?

Answer 43

Facial nerve paralysis, which may be unilateral or bilateral, can be a manifestation of any of several disease processes. These diseases can be idiopathic, neoplastic, traumatic, infectious, or congenital. The paralysis can also result from a systemic/metabolic process

Question 44

What is the anatomy of taste sensory function?

Answer 44

Taste sensory function from the anterior part of the tongue is carried along the chorda tympani of the trigeminal nerve through the submandibular ganglion to reach the facial nerve. From the posterior or pharyngeal part of the tongue, taste sensation is carried along the glossopharyngeal nerve, through the pterygopalatine ganglion, to the major petrosal nerve, and then the facial nerve. From the palatal region, the sensation is carried via the palatine nerves, which also pass through the pterygopalatine ganglion to ultimately reach the facial nerve. Along with the facial nerve, taste fibers reach the tractus solitarius, which is concerned with visceral function, including taste. Some textbooks state that taste fibers from the posterior part of the tongue reach the tractus solitarius directly by the glossopharyngeal nerve.

Question 45

How many branches does the external carotid artery give off? What are they?

Answer 45

The external carotid artery branches from the common carotid artery at the level of the upper border of the thyroid cartilage to be the principal artery supplying the anterior aspect of the neck, face, scalp, oral and nasal cavities, bones of the skull, and dura mater. Note that the orbit and its contents are the only structures that are not supplied by the external carotid. There are eight branches (order of appearance from inferior to superior): (1) the superior thyroid, (2) the ascending pharyngeal, (3) the lingual, (4) the facial, (5) the occipital, (6) the posterior auricular, (7) the internal maxillary, and (8) the superficial temporal.

Question 46

What are the muscles of mastication?

Answer 46

The muscles of mastication can be divided into two groups: primary muscles of mastication and accessory muscles of mastication. Primary muscles of mastication include the temporalis, masseter, and pterygoideus (medial and lateral). Accessory muscles of mastication include the suprahyoid group, infrahyoid group, and platysma. The suprahyoid group includes the digastric, mylohyoid, geniohyoid, and stylohyoid muscles. The infrahyoid group includes the sternohyoid, thyrohyoid, and omohyoid.

Question 47

Masseter origin and insertion

Answer 47

Origin: superficial belly from the lower border of the zygomatic arch and the zygomatic process of the maxilla. The deep belly from the posterior third and medial surface of the inferior border of the zygomatic arch. Insertion: the angle and inferior half of the lateral surface of the ramus of the mandible. The deep portion (belly) of the muscle inserts onto the lateral surface of the coronoid process and superior half of the ramus.

Question 48

Medial pterygoid origin and insertion

Answer 48

Origin: medial surface of the lateral pterygoid plate and pyramidal process of the palatine bone. A small belly of the muscle arises from the lateral surface of the pyramidal process and tuberosity of the maxilla. Insertion: inferior and posterior part of the medial surface of the ramus and angle of the mandible.

Question 49

Temporalis origin and insertion

Answer 49

Origin: the temporal fossa of the temporal bone. Insertion: medial surface, apex, and anterior border of the coronoid process of the mandible.

Question 50

Lateral pterygoid origin and insertion

Answer 50

Origin: the superior belly arises from the inferior part of the lateral surface of the greater wing of the sphenoid and from the infratemporal fossa. The inferior belly arises from the lateral surface of the lateral pterygoid plate. Insertion: the superior belly inserts into the anterior margin of the articular disc. The inferior belly inserts into a depression on the anterior portion of the neck of the condyle.

Question 51

Origin of digastric muscle

Answer 51

Origin: digastric fossa of the medial side of the lower border of the mandible close to the symphysis. The posterior belly of the muscle arises from the mastoid notch of the temporal bone. Both bellies are united by an intermediate tendon that is connected to the hyoid bone by a loop of fibrous tissue. The other suprahyoid muscle group originates from different parts of the medial surface of the mandible and inserts into the hyoid bone. The exception is the stylohyoid muscle, which arises from the temporal bone and inserts on the body of the hyoid bone. Of note is that the origin and insertion of the suprahyoid group (except stylohyoid muscle) are from a mobile origin and insertion. However, because the infrahyoid muscle group functions to stabilize the hyoid bone during mastication, this bone becomes static, allowing the mandible to move when the suprahyoid muscles contract. Inversely, during swallowing, the suprahyoid muscles stabilize the hyoid bone, allowing for swallowing action to be completed with the contraction of the infrahyoid muscles.

Question 52

How many origins and insertions does each masticatory muscle have?

Answer 52

For each muscle of mastication, there are two insertions and two origins

Question 53

What is the function of the lateral pterygoid muscle?

Answer 53

The lateral pterygoid muscle is triangular in shape and runs in a slightly inferior and posterior horizontal direction. The muscle has superior and inferior heads. The superior head arises from the infratemporal surface of the greater wing of the sphenoid and inserts into the articular capsule and disc. The function of the superior head is to stabilize the condyle and disc during closing movement. The inferior head originates from the lateral surface of the lateral pterygoid plate and inserts into the pterygoid fovea of the neck of the condyle. The inferior head aids in translation of the condyle over the articular eminence during opening of the mouth.

Question 54

Which muscles make up the pterygomandibular raphe?

Answer 54

The buccinator muscle anteriorly and the superior constrictor of the pharynx posteriorly make up the pterygomandibular raphe.

Question 55

What are the muscles of the soft palate?

Answer 55

The soft palate is formed by three pair of muscles, all of which fuse at the midline: the uvulus muscle, which runs along the uvula on each side of the midline forming almost one muscle; the levator palatine muscle extending across the midline and forming an arch-shape configuration within the soft palate; and the tensor veli palatine, which loops around the hamulus fusing with the tensor muscle of the opposite side and forming an aponeurosis at the midline.

Question 56

What class of joint is the temporomandibular joint?

Answer 56

The temporomandibular joint is classified as a diarthrodial joint. It has both features of diarthrodial joints which are ginglymus (hinge) and arthrodia (gliding) types. The articular surfaces of the fossa and the condyle are covered by nonvascular fibrous tissue that contains some cartilage cells, designated as fibrocartilage. Because of the incongruity between the articular surfaces of the joint (the mandibular condyle and the glenoid fossa and articular eminence), the joint is subdivided into an upper and lower compartments by a fibrous oval articular disc, the meniscus.

Question 57

What are the sources of the blood and nerve supply to the temporomandibular joint (TMJ)?

Answer 57

The major arterial supply to the TMJ is derived from the superficial temporal artery and from the maxillary artery posteriorly, and from smaller masseteric, posterior deep temporal, and lateral pterygoid arteries anteriorly. The venous drainage is through a diffuse plexus around the capsule and rich venous channels that drain the retrodiscal tissue. The nerve supply is from the auriculotemporal nerve, which provides the principal sensory innervation to the TMJ. The nerve gives off two or three branches, which enter the capsule inferiorly, medially, and laterally. The masseteric nerve also innervates the capsule from the frontal and medial sides of the joint. The posterior deep temporal nerve supplies the TMJ laterally and anteriorly.