Test 148  (MRCS MCQs, 2002)

1. Descemet’s membrane:

a. stains positive with PAS

b. becomes thinner with age

c. contains a banded posterior region and a non-banded 
    anterior region 

d. is made up mainly of type II collagen

e. terminates at the limbus
 

Answer
a.T   b.F   c.F   d.F   e.T
The thickness of Descemet's membrane increases with age and is continuously being laid down by the endothelium. It contains an anterior banded region which is formed by the endothelium in fetus and a posterior non-banded region which is formed after birth. The main collagens found in the Descemet's membrane are type Iv and VIII.

2. The following nerves enter the orbit outside the tendinous ring:

a. frontal nerve

b. nasociliary nerve

c. oculomotor nerve

d. trochlear nerve

e. lacrimal nerve
 

Answer
a.T   b.F  c.F  d.T  e.T

3. The following is true about trochlear nerve:

a. its nucleus is situated in the inferior colliculus

b. lesion in the nucleus causes contralateral superior 
    oblique palsy

c. is vunerable to damage in head injuries

d. is situated below the oculomotor nerve in the 
    cavernous sinus

e. it passes between the posterior cerebral artery 
    and the superior cerebellar artery
 

Answera.T  b.T  c.T  d.T  e.F
Oculomotor nerve but not trochlear nerve passes between the posterior cerebral artery and the superior cerebellar artery.

4. The inferior oblique muscle :

a. arises from the lateral orbital floor

b. runs below the inferior rectus

c. runs posteriorly to insert to the sclera near the macula

d. has the shortest tendon of all extraocular muscle

e. is supplied by the inferior division of the third cranial 
    nerve

Answer
a.F   b.T  c.T  d.T  e.T
The inferior oblique muscle arises from the medial orbital floor.

 

5. The sphenoid sinus:

a. is separated by a bony division

b. is narrowest in the anteroposterior dimension

c. may completely surrounds the optic nerve as it passes
    through the sinus

d. has the thinnest wall inferiorly

e. is situated posterior to the sella turcica
 

Answer
a.T   b.T  c.T   d.F  e.F
The sphenoid sinus is separated by a bony septum. 
It may extends into the lesser or the greater wings of sphenoid and completely surrounds the optic nerve as it enters the sphenoid bone. It is thinnest superiorly and posteriorly. The inferior floor is the strongest and thickest. The sinus may be anterior or anteroinferior to the sella turcica

 

More MCQs