5. contains axons that arise in the
oculomotor nucleus (which innervates all of
the oculomotor muscles except the superior
oblique and lateral rectus)
Edinger–Westphal nucleus (which sends
preganglionic parasympathetic axons to the
ciliary ganglion).
6. leaves the brain on the medial side of the
cerebral peduncle, behind the posterior
cerebral artery and in front of the superior
cerebellar artery.
then passes anteriorly, parallel to the
internal carotid artery in the lateral wall of
the cavernous sinus, leaving the cranial
cavity by way of the superior orbital fissure.
7. Thesomatic efferent portion of the nerve
innervates the levator palpebrae superioris
muscle; the superior, medial, and inferior
rectus muscles; and the inferior oblique
muscle
8. Thevisceral efferent portion innervates two
smooth intraocular muscles: the ciliary and
the constrictor pupillae.
9. Strabismus (squint) is the deviation of one
or both eyes.
In internal strabismus, the visual axes cross
each other
in external strabismus, the visual axes
diverge from each other
10. Diplopia (double vision) is a subjective
phenomenon reported to be present when
the patient is, usually, looking with both eyes
caused by misalignment of the visual axes
11. Ptosis (lid drop) is caused by weakness or
paralysis of the levator palpebrae superioris
muscle
seen with lesions of nerve III and sometimes
in patients with myasthenia gravis.
12. External ophthalmoplegia is characterized
by divergent strabismus, diplopia, and ptosis.
The eye deviates downward and outward.
This corresponds to the weaknesses of the
medial, superior, and inferior recti and the
inferior oblique muscles.
position of the eye is described by the
mnemonic "down and out."
13. Internal ophthalmoplegia is characterized
by a dilated pupil and loss of light and
accommodation reflexes.
There may be paralysis of individual muscles
of nerve III
14.
15. Isolatedinvolvement of nerve III (often with
a dilated pupil) occurs as an early sign in
uncal herniation because of expanding
hemispheric mass lesions that compress the
nerve against the tentorium
16. Nerve III crosses the internal carotid, where
it joins the posterior communicating artery;
aneurysms of the posterior communicating
artery thus can compress the nerve
Isolated nerve III palsy also occurs in
diabetes, presumably because of ischemic
damage, and when caused by diabetes, often
spares the pupil
17. the only crossed cranial nerve
originates from the trochlear nucleus, which
is a group of specialized motor neurons
located just caudal to the CN III nucleus
within the lower midbrain.
18. Axons cross within the midbrain, and then
emerge contralaterally on the dorsal surface
of the brain stem.
nerve then curves ventrally between the
posterior cerebral and superior cerebellar
arteries (lateral to CN III).
19. continues anteriorly in the lateral wall of the
cavernous sinus and enters the orbit via the
superior orbital fissure.
innervates the superior oblique muscle
20. rare condition
slight convergent strabismus and diplopia on
looking downward
patient cannot look downward and inward -
has difficulty in descending stairs.
head is tilted as a compensatory adjustment;
this may be the first indication of a trochlear
lesion.
21. arises from neurons of the abducens nucleus
located within the dorsomedial tegmentum
within the caudal pons.
emerges from the pontomedullary fissure,
passes through the cavernous sinus close to
the internal carotid, and exits from the
cranial cavity via the superior orbital fissure
22.
23. long intracranial course makes it vulnerable
to pathologic processes in the posterior and
middle cranial fossae.
innervates the lateral rectus muscle
24. few proprioceptive fibers from the muscles
of the eye are present in nerves III, IV, and VI
and in some other nerves that innervate
striated muscles.
central termination of these fibers is in the
mesencephalic nucleus of V
25. most common owing to the long course of
nerve VI.
weakness of eye abduction
convergent strabismus and diplopia.
affected eye deviates medially, i.e., in the
direction of the opposing muscle