Question

"Patient: 42-year-old Caucasian female

Chief complaint: ""I've been having difficulty swallowing.""
Background: No relevant patient history.
Current Findings: You notice ptosis of both eyelids and some slurring of words. The patient says that her arms feel weak and her vision is sometimes blurry. She says her symptoms tend to get worse at bedtime.
You tell the patient she might have myasthenia gravis.
The patient's ptosis is caused by weakness in a muscle (or muscles) innervated by which cranial nerve
a. CN II
b. CN III
c. CN VI
d. CN V
e. CN VII"

Answer 1

In myasthenia gravis, weakness in the muscles innervated by cranial nerve III (oculomotor nerve) causes ptosis and slurred speech. It is an autoimmune disorder that affects the neuromuscular junction.

Step-by-step explanation:

Myasthenia gravis is an autoimmune disorder that affects the neuromuscular junction. The muscle weakness and ptosis seen in this patient are caused by weakness in the muscles innervated by cranial nerve III (oculomotor nerve). Cranial nerve III controls the movement of the eyelids and certain eye muscles. In myasthenia gravis, the antibodies block the acetylcholine receptors at the neuromuscular junction, leading to muscle weakness and ptosis.