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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Which of the following is predominantly mucous?

 # Which of the following is predominantly mucous?

A. Parotid gland

B. Submandibular gland

C. Sublingual gland

D. Von  Ebner’s gland

The correct answer is C. Sublingual gland.

Sublingual gland is a mixed gland and is predominantly mucous. @ MuSuLi.

Parotid gland is purely serous gland. @ SerPa

Submandibular gland is mixed gland and is predominantly serous.

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Embryology MCQs

# Number of somatic chromosomes in humans is:
A. 42
B. 41
C. 46
D. 44

# Which of the following is true of meiosis?
A. It exclusively takes place in somatic cells
B. At the end, same number of chromosomes are maintained in the daughter cells
C. Only two daughter cells are formed at the end of meiosis
D. Crossing over and genetic variability is enhanced

Derived cephalometric landmark

 # Which of the following is a derived cephalometric landmark?

A. Nasion 

B. ANS

C. Gnathion

D. Orbitale

The correct answer is C. Gnathion

Anatomic landmarks: These landmarks represent actual anatomic structures of the skull. E.g. Nasion, ANS, PNS, orbitale, pogonion, etc. 

Derived landmarks: These are landmarks that have been srbitrarily obtained secondarily from anatomic structures in a cephalogram. E.g. Sella, gnathion, articulare, point PTM, machine porion, etc. They are not anatomical points. 

Gnathion: Gnathion is a coonstructed point at the junction of most anterior (Pogonion) and most inferior  part (menton) of the chin. 

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