CR MAN

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

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

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