Test 202  (Ocular anatomy)

1. The following are true about the superior orbital fissure:

a. it is bordered by the greater wing of the sphenoid 
    medially

b. it lies entirely in the lateral wall of the orbit

c. it transmits the superior ophthalmic vein which lies 
    laterally

d. it contains the lacrimal nerve which lies superior and 
    lateral to the trochlear nerve

e. its widest part is situated medially

 
Answera.F   b.F  c.T   d.T  e.T
The greater wing of the sphenoid bone forms the lateral wall whereas the lesser wing forms the medial wall. It lies in the roof and the lateral wall of the orbit. It transmits the superior ophthalmic vein which lies 
laterally. It also transmits three nerves that lies outside the tendinous ring: lacrimal nerve, frontal nerve and the trochlear nerve (from superolateral to inferomedial position).

 
 

2. Regarding the cervical part of the sympathetic trunk:

a. it extends from the base of the skull to just inferior to 
    the second rib

b. it lies anterior to the transverse processes of the 
    cervical vertebrae

c. it lies behind the carotid sheath

d. it possesses three ganglia

e. the stellate ganglion is formed by the fusion between 
    the inferior cervical ganglia and the first thoracic 
    ganglion. 

 

Answera.F b.T  c.T  d.T  e.T
The cervical part of the sympathetic trunk extends from the base of the skull to just inferior to the first rib. It lies anterior to the transverse processes of the cervical 
vertebrae but behind the carotid sheath. It possesses three ganglia. The inferior cervical ganglia is often used with the first thoracic ganglion to form the stellate ganglion in about 80% of the population.

 

3. The ophthalmic artery:

a. is the first branch of the internal carotid artery

b. arises from the internal carotid artery within the 
    cavernous sinus

c. lies within the meningeal sheath throughout its whole 
    length

d. provides arterial blood supply to the face

e. lies below and lateral to the optic nerve as it passes 
    through the optic canal

 
Answer
a.T   b.F  c.F  d.T e.T
The ophthalmic artery is the first branch of the internal carotid artery when the later emerges from the cavernous sinus. It pierces the meningeal sheath after emerging from the optic canal. In the optic canal, it lies inferior and lateral to the optic canal. 

 

. 4. The episclera:

a. forms the Tenon's capsule of the globe

b. receives a rich blood supply anteriorly from the anterior 
    ciliary artery

c. becomes progressively thinner towards the posterior 
    globe

d. contains dense connective tissue 

e. is derived from the mesenchyme 
 

Answer
a.F  b.T  c.T  d.F  e.T
The episclera forms the outer most layer of the sclera and is made up of loose connective tissue. It is attached to the fascial sheath of the Tenon's capsule. 

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5. The lamina cribrosa:

a. is part of the sclera

b. transmits the retinal artery and vein

c. is resistant to stretching

d. marks the point beyond which the ganglion cells 
    are myelinated.

e. contains photoreceptors on its inner surface

 
Answer
a.T   b.T  c.F  d.T  e.F
The lamina cribrosa is part of the sclera and is perforated through which ganglion cells, retinal artery and vein are transmitted. It is the weak point of the sclera and may bulge backward (if the intraocular pressure is high) or forward (if the intracranial pressure is high). The ganglion cells are myelinated posterior to the lamina cribrosa. It forms the blind spot and contains no photoreceptors.

 

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