Anatomy Answers-5

(B) The abducens (sixth cranial) nerve normally
innervates the lateral rectus muscle. The inferior
oblique (choice A), medial rectus (choice C),
and superior rectus (choice E) are all innervated
by the oculomotor (third cranial) nerve. The
superior oblique (choice D) is innervated by the
trochlear (fourth cranial) nerve. In Duane syndrome,
the absence of lateral rectus innervation
by the abducens (sixth cranial) nerve is replaced
by an aberrant innervation of the oculomotor
(third cranial) nerve. Thus when the patient is
asked to adduct the affected eye, there is cocontraction
of the lateral and medial recti with
globe retraction.

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