A 32-year-old woman comes to the office due to a 2-day history of worsening headache and double vision. The patient reports no chronic medical conditions but has had nasal discharge for the past several days. Physical examination shows weakness of the muscle shown on the below CT scan: Purulent discharge from the sphenoethmoidal recess of the nasal cavity is also noted. Involvement of which of the following nerves best explains this patient's ocular findings?

Question

A 32-year-old woman comes to the office due to a 2-day history of worsening headache and double vision.  The patient reports no chronic medical conditions but has had nasal discharge for the past several days.  Physical examination shows weakness of the muscle shown on the below CT scan:  Purulent discharge from the sphenoethmoidal recess of the nasal cavity is also noted.  Involvement of which of the following nerves best explains this patient's ocular findings?

Quizplus · Accepted Answer

11ec160b_35a3_a0d0_9249_cf912b261cdf_MD0001_00 The arrow in the above CT scan points to an extraocular muscle that originates at the annular tendon and inserts onto the temporal (ie, lateral) surface of the globe. The extraocular muscles control movement of the globe; dysfunction leads to double vision. They are innervated by the following: The oculomotor nerve (CN III) innervates the superior rectus, medial rectus, inferior rectus, inferior oblique, and levator palpebrae superioris. It also contributes parasympathetic innervation to the ciliary muscle and iris sphincter for the efferent path of the pupillary reflex (Choice B). The trochlear nerve (CN IV) innervates only the superior oblique muscle, which causes the eye to intort (internally rotate) and depress while adducted (Choice C). The abducens nerve (CN VI) innervates the lateral rectus muscle, which abducts the eye. Acute sinusitis can have significant complications, including cavernous sinus thrombosis due to contiguous spread of an infection through the valveless facial venous system. This can cause dysfunction of nerves that travel through the cavernous sinus, including those that innervate the extraocular muscles. (Choice A) The optic nerve (CN II) transmits visual information to the brain; damage to this nerve causes loss of vision. The optic nerve has no role in movement of the globe. (Choice D) The ophthalmic division of the trigeminal nerve (CN V) conveys sensory information from the forehead, side of the nose, periorbital area, and cornea. It does not contribute motor innervation to the extraocular muscles. Educational objective: The abducens nerve (CN VI) innervates the lateral rectus muscle, which originates at the annular tendon and inserts on the temporal (ie, lateral) surface of the globe. It functions to abduct the eye.

A 32-Year-Old Woman Comes to the Office Due to a 2-Day