Anatomy

Question 1

Which muscle listed below does not insert into the modiolus located at the commisures of the lip?

a. Buccinator
b. Orbicularis oris
c. Triangularis
d. Mentalis
e. Caninus

Answer 1

d. Mentalis

Question 2

What muscle(s) of mastication is responsible for depressing the mandible?

Answer 2

Lateral pterygoid only.

Question 3

What nerve innervates ALL of the muscles of mastication?

Answer 3

Mandibular branch of trigeminal nerve.

Question 4

What major muscles, arteries, veins and nerves that occupy the infra-temporal fossa?

Answer 4

Temporalis/Lateral pterygoid/medial pterygoid muscles, maxxilary artery, pterygoid plexus of veins, mandibular division of trigeminal nerve, posterior superior alveolar nerve, chorda tympani branch of the facial nerve.

Question 5

Innervation to: a) Posterior 1/3rd of tongue b) Anterior 2/3rd of tongue (sensory and which is taste?)

Answer 5

a) Glossopharyngeal (IX) and Vagus (X) b) Sensory = trigeminal → lingual nerve, Taste = VII → chorda tympani.

Question 6

What is the most common maxillary space to get an infection?

Answer 6

Buccal space.

Question 7

Ludwig’s angina involves which mandibular spaces? Why is it more common with second and third molars?

Answer 7

Submandibular and sublingual spaces. More common with second and third molars because the root apices are below the mylohyoid ridge (where mylohyoid attaches and prevents spread through the space).

Question 8

What are the symptoms of cavernous sinus thrombosis? What three pathways are usually involved in the spread of infection?

Answer 8

Symptoms: Peri-orbital edema and opthalmoplegia (can’t move eyeball), fever, severe headache that doesn’t go away with medications, paresthesia in the forehead, redness/hot cheeks.

Potential origins: Facial vein, angular vein or superior ophthalmic vein to cavernous sinus.

Question 9

What are the contents of the submandibular triangle?

Answer 9

Facial/Submental/Lingual arteries and veins. Mylohyoid and hypoglossal nerve. Submandibular gland and lymph nodes.

Question 10

What is the most injured nerve in all of dentistry? How can you test this patient to see if they are telling you the truth about their paresthesia?

Answer 10

Lingual nerve. Test positive for => a) Loss of 2-point discrimination b) No distinction between sharp and dull pain 3) No distinction between vertical and horizontal.

Question 11

Where does the maxillary sinus open?

Answer 11

Sinus opens into the lateral wall of the nose between the middle and infereior conchae (i.e. middle meatus). The opening is located in the posterior portion of a semilunar groove called the hiatus semiluminaris.

Question 12

11) Name the nerve(s) whose injury would lead to the following clinical signs.
a. Inability to close the right eye
b. Inability to blow the mouth
c. Inability to show the teeth on the left side
d. Inability to stretch the skin of the neck
e. Inability to wrinkle the skin of the forehead or raise the eye brow on the right

Answer 12

a. Inability to close the right eye = infraorbital and temporal
b. Inability to blow the mouth = mental nerve (lower lip) and infraorbital (upper lip)
c. Inability to show the teeth on the left side = facial nerve
d. Inability to stretch the skin of the neck = auriculo-temporal nerve (coming from V3)
e. Inability to wrinkle the skin of the forehead or raise the eye brow on the right = temporal nerve

Question 13

What are the symptoms of trigeminal neuralgia (Tic Douloureux)? What part of the face does the patient NOT have pain? Explain why.

Answer 13

Sharp stabbing excruciating pain that lasts a few seconds in the region of the skin of the face supplied by one or more of the trigeminal division. Pain starts when patient touches a trigger point on the face. Part of the face with no pain is angle of the mandible (because this is supplied by the greater auricular nerve → this comes from a cervical nerve).

Question 14

The retromolar triangle is bound medially by extensions of the a) _______, and buccally by b) ________.

Answer 14

a) Internal oblique ridge b) External oblique ridge

Question 15

What foramen in the skull does the mandibular nerve exit?

Answer 15

Foramen ovale.

Question 16

What foramen in the skull does the maxillary nerve exit?

Answer 16

Foraman rotundum.

Question 17

Pterygomandibular raphe is the link between the a) _________ and b) ___________ muscles.

Answer 17

a) buccinator b) superior constrictor muscles

Question 18

The maxillary sinus gets its blood supply from the a) __________, which gets ITS blood supply from the b) _________.

Answer 18

a) maxillary artery b) external carotid

Question 19

The mental foramen is approximately ____ mm to ____ mm from the midline.

Answer 19

20.5 to 22 mm from the midline

Question 20

The anterior loop of the mental nerve extends how far anteriorly?

Answer 20

2 to 5 mm

Question 21

Over 50% of the time, the mental foramen exits at what tooth location?

Answer 21

second premolar

Question 22

What vessel is compromised when you have bleeding at the

a) posterior mandible
b) middle lingual of mandible
c) anterior lingual of mandible
d) from the mandibular canal? How would you manage each?

Answer 22

a) posterior mandible = mylohyoid artery → finger pressure b) middle lingual of mandible = submental artery → surgical ligation of facial and lingual arteries
c) anterior lingual of mandible = terminal branch of sublingual or submental → compression, vasoconstriction, cautery or ligation
d) mandibulary canal = inferior alveolar artery → bone graft

Question 23

Define nurapraxia, axonotmesis and neurotmesis.

Answer 23

Neurapraxia = mild injury or retraction of nerve, no axonal degeneration or violation of nerve trunk → management with corticosteroids. 
Axonotmesis = nerve injury with loss of axon continuity but general structure intact → Wallerian degeneration → corticosteroids. 
Neurotmesis = complete severance of nerve trunk → Wallerian degeneration → complete anesthesia for more than 3 months.