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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Superior meatus of nose has opening of:

 # Superior meatus of nose has opening of:

A. Middle ethmoidal sinus

B. Anterior ethmoidal sinus

C. Posterior ethmoidal sinus

D. Middle ethmoidal sinus and Anterior ethmoidal sinus

The correct answer is C. Posterior ethmoidal sinus. 

Meatuses are passages behind the overhanging conchae. 

INFERIOR MEATUS

- Largest of all three

- Nasolacrimal duct opens into it. This opening is guarded by lacrimal fold or Hassner valve.

- Lies underneath inferior concha

MIDDLE MEATUS

- Lies underneath middle concha

- Most air sinuses open into it: Frontal air sinus, Maxillary Sinus, Middle ethmoidal sinus and anterior ethmoidal sinus

SUPERIOR MEATUS

- Below superior concha

- Shallowest of all the three

- Posterior ethmoidal sinus opens into it

# Nasolacrimal Duct opens into Inferior meatus of nasal cavity.

# The frontal paranasal sinus drains into the middle meatus of the nasal cavity.

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