Oral diaphragm is formed by:

 # Oral diaphragm is formed by:

A. Mylohyoid muscle

B. Genioglossus muscle

C. Buccinator muscle

D. Orbicularis oris muscle

The correct answer is A. Mylohyoid muscle.

The mylohyoid muscle or diaphragma oris is a paired muscle running from the mandible to the hyoid bone, forming the floor of the oral cavity of the mouth.

The mylohyoid muscle is flat and triangular, and is situated immediately superior to the anterior belly of the digastric muscle. It is a pharyngeal muscle (derived from the first pharyngeal arch) and classified as one of the suprahyoid muscles. Together, the paired mylohyoid muscles form a muscular floor for the oral cavity of the mouth.

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The action of digastric muscle is:

 # The action of digastric muscle is:

A. Depression of mandible

B. Protrusion of mandible

C. Side to side movement of the mandible

D. Depressing the floor of the mouth

The correct answer is A. Depression of mandible.

The digastric muscle is involved in any complex jaw action such as speaking, swallowing, chewing and breathing.

When the digastric muscle contracts, it acts to elevate the hyoid bone.

If the hyoid is being held in place (by the infrahyoid muscles), it will tend to depress the mandible (open the mouth).

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Nasopharynx is connected to:

 # Nasopharynx is connected to ______________ through pharyngotympanic tube.

A. Middle ear

B. Outer ear

C. Middle meatus

D. Semilunar canals

The correct answer is A. Middle ear.

The middle ear lies in the temporal bone, where the chain of three ear ossicles connect the tympanic membrane to the oval window. The middle ear cavity communicates with the nasopharynx via the eustachian tube, which allows air pressure to be equalized on both sides the tympanic membrane. 

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Nasal cavity receives blood supply from:

 # Nasal cavity receives blood supply from:

A. Facial artery

B. Maxillary artery

C. Ophthalmic artery

D. All of the above

The correct answer is D. All of the above

Nasal cavity receives blood supply from superior labial, a branch of facial artery; anterior posterior ethmoidal , a branch of ophthalmic artery; Sphenopalatine and greater palatine, a branch of maxillary artery. So, the correct answer is D. All of the above.

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