The cornea is nourished by:

 # The cornea is nourished by:

A. Aqueous humor

B. Lymphatic fluid

C. Lacrimal fluid

D. All of the above

The correct answer is B. Lymphatic fluid.

The cornea is more convex than the sclera, but the curvature diminishes with age. It is separated from the iris by a space called the anterior chamber of the eye. The cornea is avascular and is nourished by lymph which circulates in the numerous corneal spaces. Pain is the only sensation aroused from the cornea. 

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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). 

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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. 

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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. 

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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". 

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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. 

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