Middle concha of nose are a part of:

 # Middle concha of nose are a part of:

A. Nasal bone

B. Ethmoid

C. Vomer

D. Maxilla

The correct answer is B. Ethmoid.

The nasal conchae are curved bony projections directed downward and medially. 

The 3 conchae are:

 i) Inferior concha: It is an independent bone. 

ii) Middle concha: It is a projection from the medial surface of the ethmoidal labyrinth.

iii) Superior concha: It is also a projection from the medial surface of the ethmoidal labyrinth. This is the smallest concha situated just above the posterior part of middle concha. 

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Carboxylation reaction is related to:

 # Carboxylation reaction is related to:

A. Biotin

B. Vitamin B6

C. Vitamin C

D. Vitamin A

The correct answer is A. Biotin.

Biotin serves as a carrier of CO2 in carboxylation reactions. The reaction catalyzed by pyruvate carboxylase, converting pyruvate to oxaloacetate.

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Which bone reaches its adult size at birth?

 # Which bone reaches its adult size at birth?

A. Ear ossicles

B. Parietal bone

C. Mastoid process

D. Maxilla

The correct answer is A. Ear ossicles.

The bone that reaches its adult size at birth are ear ossicles. The tympanic cavity, mastoid antrum, auditory ossicles and structures of the internal ear are almost fully developed at birth and undergo little change after birth.

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Metopic suture fuses at:

 # Metopic suture fuses at:

A. 2.5 years

B. 6 years

C. 18 months

D. 9 months

The correct answer is D. 9 months.

The two frontal bones tend to fuse in the midline via the metopic or frontal suture. The timing of its closure is controversial. Fusion of metopic suture begins anteriorly at the bridge of the nose and progresses posteriorly. One-third of metopic sutures close at 3 months, and nearly 100% by 9 months. Although some may persist into 6 years and may not close until adulthood in up to 10% of patients. A premature fusion of the suture is termed metopic synostosis. This can result in trigonocephaly. It usually disappears by the age of 2 years but may even persist in a few individuals. 

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