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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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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Process of preparing ceramic prosthesis

 # The process of preparing ceramic prosthesis from glassy ingot is:

A. Casting

B. Slip casting

C. Heat pressed

D. Copy milling

The correct answer is: A. Casting.

Dental ceramics are formed into prosthetic shapes and configurations through a variety of processes including sintering, casting, hot isostatic pressing, copy milling, and CAD CAM machining.

- Ceramic prosthesis from glassy ignots is produced by casting.

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Preterm birth meaning

 # In humans, preterm birth refers to the birth of a baby of less:

A. Than 37 weeks gestational age

B. Than 41 weeks gestational age

C. Than 30 weeks gestational age

D. Than 38 weeks gestational age

The correct answer is A. Less than 37 weeks gestational age.

In humans preterm birth is the birth of a baby of less than 37 weeks gestational age. Premature birth is defined either as the same as preterm birth or the birth of a baby before the developing organs are mature enough to allow the survival of the baby after it is born.

Several organ systems mature between 34-37 weeks in the normal human fetus to reach adequate maturity. 

One of  the main organs greatly affected by premature birth is the lungs. The lungs are one of the last organs to develop. Because of this, premature babies typically spend the first days/weeks of their life on a ventilator. 

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