Trachea bifurcates at the level of:

 # Trachea bifurcates at the level of:

A. C7

B. Lower border of T3

C. Upper border of T4

D. Upper border of T5

The correct answer is D. Upper border of T5.

Trachea begins at C6 and bifurcates at the level of T5. Trachea bifurcates at the level of sternal angle.

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Carotid Sinus vs Carotid body

 # Select the incorrect statement about the carotid sinus:

A. It is a dilatation near the beginning of the internal carotid artery

B. It is innervated by the glossopharyngeal nerve

C. It acts as a chemoreceptor

D. Its wall has thick tunica adventitia

The correct answer is C. It acts as a chemoreceptor; which is incorrect because carotid sinus is a baroreceptor. 

Carotid Sinus : The termination of the common carotid artery, or the beginning of the internal carotid artery shows a slight dilatation, known as the carotid sinus which receives a rich innervation from the glossopharyngeal and sympathetic nerves. The carotid sinus acts as a baroreceptor or pressure receptor and regulates blood pressure.

Carotid Body: Carotid body is a small, oval reddish-brown structure situated behind the bifurcation of the common carotid artery. It receives a rich nerve supply mainly from the glossopharyngeal nerve, but also from the vagus and sympathetic nerves. It acts as a chemoreceptor and responds to changes in the oxygen and carbon dioxide and pH content of the blood.

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The base of the submental triangle is formed by:

# The base of the submental triangle is formed by:

A. Chin

B. Anterior belly of digastric

C. Posterior belly of digastric

D. Hyoid bone

The correct answer is D. Hyoid bone.

Submental triangle is a median triangle. On each side, there is the anterior belly of the corresponding digastric muscles. Its base is formed by the body of the hyoid bone. Its apex lies at the chin. The floor of the triangle is formed by the right and left mylohyoid muscles and the median raphe uniting them.

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All of the infrahyoid muscles are supplied by ansa cervicalis EXCEPT:

 # All of the infrahyoid muscles are supplied by ansa cervicalis EXCEPT:

A. Thyrohyoid

B. Sternohyoid

C. Sternothyroid

D. Inferior belly of omohyoid

The correcct answer is A. Thyrohyoid.

Infrahyoid muscles are sternohyoid, sternothyroid, thyrohyoid and omohyoid present in the superficial plane of the anterior triangle of neck. Sternohyoid, sternothyroid, omohyoid are supplied by ansa cervicalis EXCEPT thyrohyoid which is supplied by the first cervical nerve through hypoglossal nerve.

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