A 67-year-old male presents with a history of chronic
cough. He smokes 20 cigarettes a day and has done so for 40 years.
On examination he has a partial ptosis of his right
eyelid and a constricted pupil on the right side. There is reduced sweating on
the right side of his face.
On examination of his hands you note that there is
wasting of all the small muscles of his right hand.
Examination of the chest shows that the trachea is
deviated to the right and there are bronchial breath sounds over the right
apex with fine crepitations in this region.
In this patient the wasting of the small muscles of his
hand is due to the lesion affecting nerve root: