Medial squint may be the result of a lesion involving:

 # Medial squint may be the result of a lesion involving:

A. III cranial nerve

B. IV cranial nerve

C. VI cranial nerve

D. Optic nerve

The correct answer is. C. VI cranial nerve.

Medial squint is the result of palsy of lateral rectus of eye. All the extraocular muscles are supplied by the third cranial nerve (Oculomotor nerve) EXCEPT Lateral rectus which is supplied by sixth cranial nerve (Abducent nerve) and Superior Obique which is supplied by fourth cranial nerve (Trochlear nerve). 

CLICK HERE FOR MORE MCQs

Superior rectus helps in:

 # Superior rectus helps in all of the following movements EXCEPT:

A. Upward rotation

B. Lateral rotation

C. Intorsion

D. Medial rotation

The correct answer is B. Lateral rotation. 

All the rectus muscles are involved in medial rotation of eye except the lateral rectus. Lateral rectus is the only rectus muscle involved in lateral rotation. 

CLICK HERE FOR MORE MCQs

Muscles is involved in elevation of the eyeball

 # Which of the following group of muscles is involved in elevation of the eyeball?

A. Superior rectus and inferior oblique

B. Inferior rectus and Superior oblique

C. Superior Oblique and superior rectus

D. Inferior oblique and Inferior rectus

The correct answer is : A. Superior rectus and inferior oblique

Action of Individual Muscles:

Levator Palpebrae superioris - Elevation of upper eyelid

Superior rectus - Upward rotation, medial rotation and intorsion

Inferior rectus- Downward rotation, medial rotation and extorsion

Medial rectus- Medial rotation

Lateral rectus- Lateral rotation

Superior oblique- Downward rotation, lateral rotation and intorsion 

Inferior oblique- Upward rotation and extorsion

Single movements of eyeball and muscles involved:

Upward rotation (Elevation)- Superior rectus and inferior oblique

Downward rotation (Depression)- Inferior rectus and Superior oblique

Medial rotation (Adduction)- Medial rectus, Superior rectus and Inferior rectus

Lateral rotation (Abduction)- Lateral rectus, Superior oblique and inferior oblique

Intorsion- Superior rectus and superior oblique

Extorsion- Inferior oblique and Inferior rectus

Nasolacrimal duct is directed:

 # Nasolacrimal duct is directed:

A. Downward, medially, backwards

B. Downward, laterally, backwards

C. Downward, laterally, forward

D. Downward, medially, forward

The correct answer is: B. Downward, laterally, backwards

Nasolacrimal duct: The groove for nasolacrimal duct is located medially near the orbital margin. It is a membranous passage of 18 mm length. It begins at the lower end of the lacrimal sac, runs downwards, backwards and laterally, and opens into the inferior meatus of the nose. A fold of mucous membrane called the valve of Hasner forms an imperfect valve at the lower end of the duct. 

CLICK HERE FOR ALL MCQs

Stapedius muscle has its nerve supply from:

 # Stapedius muscle has its nerve supply from:

A. Trigeminal nerve

B. Facial nerve

C. Glossopharyngeal nerve

D. Stato-acoustic nerve

The correct answer is: B. Facial nerve

Stapedius muscle along with the tensor tympani are muscles of ossicles of middle ear. Stapedius is supplied by facial nerve, whereas tensor tympani is supplied by mandibular nerve. Stapedius and tensor tympani both act simultaneously to damp down the intensity of high pitched sound waves, thus protecting the internal ear. In paralysis of the muscle even normal sounds appear too loud, which is known as "hyperacusis". 

CLICK HERE FOR MORE MCQs

Lower one third of pinna is supplied by:

 # The lower one-third of pinna is supplied by:

A. Auriculotemporal nerve

B. Great auricular nerve

C. Lesser occipital nerve

D. Vagus nerve

The correct answer is: B. Great Auricular Nerve.

Greater auricular nerve supplies lower one third of both lateral and medial surface of pinna. Auriculotemporal nerve supplies upper 2/3rds of lateral surface of pinna. Lesser occipital supplies upper 2/3rds of medial surface of pinna. Vagus nerve supplies root of the pinna. Facial nerve supplies muscles of pinna. 

CLICK HERE TO VIEW MORE MCQs

Dangerous area of the face

 # Which of the following areas are regarded as the ‘dangerous area’ of the face?

A. Chin and lower lips

B. Lower and upper lips

C. Upper lip and lower part of the nose

D. Upper part of nose and forehead

The correct answer is C. Upper lip and lower part of the nose.

The dangerous area of the face is drained by the facial vein. Deep connections of the facial vein with cavernous sinus includes:

i. A communication between the supraorbital and superior ophthalmic veins. 

ii. Another with the pterygoid plexus through the deep facial vein which passes backwards over the buccinator. The pterygoid venous plexus in turn communicate with the cavernous sinus through an emissary vein. The veins of the dangerous area of face are valveless. Movements of the facial muscles and absence of valves in the facial vein might facilitate retrograde flow of blood. This allows retrograde infection, which is carried by facial, angular and nasofrontal veins and superior ophthalmic veins into cavernous sinus. This can lead to spread of septic emboli from the dangerous area of the face and can cause cavernous sinus thrombosis with serious complications. 

Eagleton criteria for diagnosis of cavernous sinus thrombosis are:

- Known site of infection

- Paralysis of 3,4,6 nerves

- Proptosis of eye due to increased pressure in superior and inferior veins of the orbit.

CLICK HERE FOR MORE MCQs