Dynamic receptors of the TMJ joint:

 # Which of the following are dynamic receptors of the TMJ joint?

A. Ruffini endings

B. Pacinian corpuscles

C. Golgi tendon

D. Free nerve endings

The correct answer is B. Pacinian corpuscles

Pacinian corpuscles  are dynamic mechanoreceptors which accelerate movement during reflexes. 

The receptors for specific mechanics of proprioception:

Ruffini endings- static  mechanoreceptors which position the mandible

Pacinian corpuscles- Dynamic mechanoreceptors which accelerate movement during reflexes

Golgi tendon organs- Static mechanoreceptors for protection of ligaments around the temporomandibular joint

Free nerve endings- Pain receptors for protection of the temporomandibular joint itself

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Articular disc of TMJ is

 # Articular disc of TMJ is:

A. Fibrocartilaginous

B. Bony

C. Hyaline cartilage

D. Elastic cartilage

The correct answer is A. Fibrocartilaginous

The unique feature of the TMJ is the articular disc. The disc is composed of fibrocartilaginous tissue which is positioned between the two bones that form the joint. There is neither innervation nor vascularization within the central portion of the articular disc. Articular disc is oval fibrous plate with concavoconvex superior surface and concave inferior surface. It divides joint into upper and lower compartments. Upper compartment permits gliding and lower permits gliding as well as rotatory movements. 

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Sublingual salivary gland is located:

 # Sublingual salivary gland is located superior to:

A. Genioglossus

B. Hyoglossus

C. Mylohyoid

D. None of the above

The correct answer is C. Mylohyoid.

Sublingual salivary gland lies superior to mylohyoid and lateral to the genioglossus muscle. Its duct opens directly into floor of mouth on the summit of sublingual fold.

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Opening of submandibular gland duct:

 # The opening of submandibular gland duct into oral cavity is at:

A. Maxillary Second molar

B. Mandibular third molar

C. Dorsum of tongue

D. Sublinugual caruncle

The correct answer is D. Sublingual caruncle.

Submandibular duct or Warthin's duct is 5 cm long, emerges from submandibular gland and in its course runs on the hyoglossus between lingual and hypoglossal nerve and opens at the sublingual papilla at the side of frenum of tongue.

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Ideal class V restoration

 # For an Ideal class V restoration on a mandibular premolar, which of the following is the MOST IMPORTANT factor when choosing a restorative material?

A. Ease of manipulation of material

B. Esthetics

C. Compressive strength

D. Reaction of gingival tissue

The correct answer is D. Reaction of gingival tissue.

Restorative materials that do not induce gingival tissue reaction should be considered when selecting the proper restorative material for class V restorations.

Esthetics are not a factor because the class V restoration in question is placed at the cervical area of a mandibular premolar and is not within the esthetic zone.

Compressive strength is only required for occlusal restorations or those cavities which are under heavy occlusal load.

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Secretomotor fibres from inferior salivary nucleus supply:

 # Secretomotor fibres from inferior salivary nucleus supply:

A. Lacrimal gland

B. Parotid gland

C. Submandibular salivary gland

D. Sublingual salivary gland

The correct answer is B. Parotid gland.

The preganglionic fibres begin in the inferior salivatory nucleus, pass through the 9th cranial nerve and relay in the otic ganglion. The post ganglionic fibres reach the gland through the auriculotemporal nerve.

# Inferior salivatory nucleus --> IX cranial nerve tympanic branch ----> tympanic plexus ---> Lesser petrosal nerve ---> relays in otic ganglion ---> parotid gland.

# Edinger westphal nucleus ---> III nerve ---> Inferior oblique ---> Branch to ciliary ganglion ---> relay ---> short ciliary nerves supply cliliaris and constrictor pupillae muscle.

# Superior salivatory nucleus of VII nerve ---> VII nerve ---> chorda tympani branch --->  via lingual nerve ---> submandibular ganglion ---> relays ---> submandibular gland and lingual salivary salivary gland via lingual nerve.

# Lacrimatory nucleus of  VII nerve ---> VII nerve---> greater petrosal nerve + deep petrosal nerve ---> nerve of pterygoid canal ---> Pterygopalatine ganglion ---> relays to supply glands of nose, palate, pharynx and pass along maxillary nerve, zygomatic, temporal nerve, lacrimal nerve to supply lacrimal gland.

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Orifice of parotid duct:

 # The orifice of parotid duct is located:

A. At the hamular notch

B. In proximity to the incisive papilla

C. On the buccal mucosa near the maxillary second molar

D. Slightly posterior to the mandibular central incisors

The correct answer is C. On the  buccal mucosa near the maxillary second molar

Parotid duct is 5 cm long, thick walled and it emerges from anterior border of the gland and runs on the masseter muscle. At the anterior border of masseter it turns medially and pierces: 

• Buccal pad of fat
• Buccopharyngeal fascia
• Buccinator (obliquely)

Then, the duct runs forwards and obliquely for a short course between buccinator and oral mucosa. This acts as  a valve which prevents inflation of ductt during blowing. Finally it opens into the vestibule of mouth, at upper second molar tooth. 

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