A 41-tear-old man is injured in a motorcycle accident. He is taken to the hospital by a rescue helicopter and treated for abdominal spinal ,and head injures. Three weeks later he is examined by a neurologist,who notes that the patient has left-sided facial swelling and discoloration, slight drooping of the left eyelid,and a constricted pupil on the left side. There are no other motor or sensory abnormalities. Which of the following is the most likely cause of this patient's ocular disorder?

A 41-tear-old man is injured in a motorcycle accident. He is taken to the hospital by a rescue helicopter and treated for abdominal spinal ,and head injures. Three weeks later he is examined by a neurologist,who notes that the patient has left-sided facial swelling and discoloration, slight drooping of the left eyelid,and a constricted pupil on the left side. There are no other motor or sensory abnormalities. Which of the following is the most likely cause of this patient's ocular disorder?

A 41-tear-old man is injured in a motorcycle accident. He is taken to the hospital by a rescue helicopter and treated for abdominal spinal ,and head injures. Three weeks later he is examined by a neurologist,who notes that the patient has left-sided facial swelling and discoloration, slight drooping of the left eyelid,and a constricted pupil on the left side. There are no other motor or sensory abnormalities. Which of the following is the most likely cause of this patient's ocular disorder?



(A)a lesion of cranial nerve VI
(B)A lesion of the midbrain
(C)A lesion of the oculomotor nerve
(D)A lesion of the thoracic spinal cord
(E)Myasthenia gravis

Answer: (D) A lesion of the thoracic spinal cord