A knife wound has severed the oculomotor nerve in a 45-year-old man. Which of the following conditions will occur because of this injury?
1.Constricted pupil
2.Complete ptosis
3.Paralysis of the ciliary muscle
4.Impaired lacrimal secretion
5.Abduction of the eyeball
Explanation:
The oculomotor nerve carries parasympathetic fibers to the ciliary and sphincter pupillae ciliary muscles; thus, a lesion of the oculomotor nerve leads to ciliary muscle paralysis and a dilated pupil. The abducens nerve supplies the lateral rectus, which is an abductor of the eye. The levator palpebrae superioris inserts on the tarsal plate in the upper eyelid, which is innervated by sympathetic fibers. Thus, a lesion of the oculomotor nerve does not cause complete ptosis. The secretomotor fibers for lacrimal secretion come through the pterygopalatine ganglion. Thus, severance of the oculomotor nerve has no effect on lacrimal secretion.