Question

Which of the following congenital extraocular muscle disorders occurs as a result of failure of innervation of the lateral rectus muscle by the sixth cranial nerve, accompanied by anomalous innervation of the lateral rectus by fibers from the third cranial nerve?

Mobius syndrome Duane's retraction syndrome Brown's syndrome Marcus Gunn jaw-winking Congenital fibrosis of extraocular muscles

Answer 1

Duane's retraction syndrome is the congenital extraocular muscle disorder caused by the failed innervation of the lateral rectus muscle by the abducens nerve and anomalous innervation by the oculomotor nerve.

Step-by-step explanation:

The congenital extraocular muscle disorder that you are referring to, which occurs as a result of failure of innervation of the lateral rectus muscle by the sixth cranial nerve and aberrant innervation from fibers of the third cranial nerve, is known as Duane's retraction syndrome. This syndrome is characterized by a limited ability to move the eye outward toward the ear (abduction) and sometimes inward toward the nose (adduction). It can also result in retraction of the eyeball into the socket when attempting to look inward, and occasionally, up or down eye movements may also be affected.

The sixth cranial nerve, also known as the abducens nerve, is normally responsible for contraction of the lateral rectus muscle, which abducts the eye. Similarly, the other extraocular muscles are generally controlled by either the third cranial nerve, referred to as the oculomotor nerve, for most muscles, or by the fourth cranial nerve, known as the trochlear nerve, for the superior oblique muscle.