Test 204  (Ocular anatomy)

1. The levator superioris palpebris:

a. opposes the action of the superior rectus

b. opposes the action of the orbicularis oculi

c. is supplied entirely by the upper division of the third 
    nerve

d. is attached to both the tarsal plate and the skin

e. originates from the greater wing of the sphenoid bone

 
Answera.F  b.T  c.T  d.T  e.F
The orbicularis oculi originates from the lesser wing of 
the sphenoid bone. It is supplied entirely by the upper division of the third nerve (the Muller's muscle is not part of the levator and is supplied by the sympathetic nerve). It is attached to the orbit, tarsus and the skin. It opposes the action of the orbicularis oculi.
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2. The abducens nerve nucleus:

a. communicates with the fourth and third nerve nuclei via 
    the reticular formation

b. supplies fibres that innervate the contralateral lateral 
    rectus 

c. supplies fibres that innervate the rectus muscle on its 
    corneal surface

d. if damaged, produces ipsilateral internuclear
    ophthalmoplegia

e. is ventral to the facial nerve nucleus.
 

Answera.F  b.F  c.T  d.F  e.F
The abducens nerve nucleus communicates with the 
fourth and the third nerve nuclei via the medial longitudinal fasciculus. It supplies the ipsilateral lateral rectus 
through its corneal surface. Damage of the nucleus causes a one and a half syndrome. Internuclear
ophthalmoplegia
occurs in lesion of the medial longitudinal fasciculus. The nucleus is dorsal to the facial nerve nucleus.

3. Regarding the ciliary body:

a. it contains about 70 ciliary processes

b. it contains two layers of cuboidal cells which lies base 
    to base

c. the par plicata is adjacent to the ora serrata

d.  it is supplied by the short ciliary nerves that carry 
     the parasympathetic nerves

e. the longitudinal fibres of the ciliary body is anterior
    to the circular fibres

 
Answer
a.T   b.F  c.F  d.T e.F
The ciliary body contains about 70 ciliary processes at a region known as the par plicata. The par plana is adjacent to the ora serrata. The ciliary muscle 
contains circular, longitudinal and oblique fibres. The circular fibres is the most anteriorly located. 

 

. 4. The superior cervical ganglion:

a. contains both parasympathetic and sympathetic fibres

b. gives off branches that supply the heart 

c. is the only cervical ganglion that supplies the cranial 
    nerves

d. gives off branches that supply the sweat glands of 
    the face

e. if damaged affects ipsilateral accommodation
 

Answer
a.F  b.T  c.T  d.T  e.F
The cervical ganglia including the superior cervical ganglion contains only the sympathetic fibres and not parasympathetic fibres. The ganglia give off 
branches to the heart. Only the superior cervical ganglion gives off branches to the cranial nerves, the other two ganglia ie.  the middle and inferior ganglia provide sympathetic fibres to the cervical nerves. Damage of the superior cervical ganglion produces ipsilateral 
anhydrosis, ptosis, apparent enophthalmos and miosis. Accommodation is not affected.

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5. The long ciliary nerve:

a. is a branch of the nasociliary nerve

b. provides sensory supply to the cornea

c. contains postganglionic sympathetic fibres from 
    the superior cervical sympathetic ganglion

d. contains postganglionic parasympathetic fibres from 
    the ciliary ganglion 

e. innervate the constrictor pupillae muscle

 
Answer
a.T   b.T  c.T  d.F  e.F
The long ciliary nerve contains postganglionic sympathetic fibres from the superior cervical sympathetic ganglion and innervates the dilator pupillae muscle. The short ciliary nerve arises from the ciliary ganglion and contains postganglionic parasympathetic fibres from the ciliary ganglion and supplies the contrictor pupillae muscle.

 

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