A nurse is caring for a 63-year-old male client in the emergency department.

Complete the diagram by dragging from the choices below to specify which cranial nerve is being assessed, two actions the nurse should take to further assess that cranial nerve, and two parameters the nurse should monitor to assess the client’s progress.

Condition: cranial nerve iii
2 actions: assess pupillary constriction, assess lateral eye movement
2 parameters: pupil constriction, lateral eye movement

Rationale for correct condition
cranial nerve iii (oculomotor nerve) controls most extraocular movements and pupillary constriction. stroke affecting this nerve can cause ptosis, impaired eye movement, and abnormal pupillary response. in this client with stroke symptoms and altered neurologic status, assessing cranial nerve iii function is critical to detect brainstem involvement. pupillary dysfunction may indicate increased intracranial pressure or herniation. thus, cranial nerve iii assessment provides vital information about neurological progression.

Rationale for correct actions
assessing pupillary constriction tests the parasympathetic fibers of cranial nerve iii responsible for the pupillary light reflex, critical for detecting brainstem integrity. abnormal or unequal pupil responses can indicate oculomotor nerve damage or increased intracranial pressure. assessing lateral eye movement checks for oculomotor nerve motor function, as it innervates most extraocular muscles controlling eye movements except the lateral rectus and superior oblique. impaired lateral gaze or eye deviation may signal cranial nerve iii palsy due to stroke-related ischemia or compression.

Rationale for correct parameters
monitoring pupil constriction quantitatively tracks parasympathetic function and neurological status; normal pupil size ranges from 2 to 4 mm in bright light. changes in pupil size or reaction can signal worsening cerebral edema or brain herniation. monitoring lateral eye movement evaluates motor function of extraocular muscles; loss of coordinated movement indicates cranial nerve iii dysfunction. recovery or deterioration of these parameters guides treatment and prognosis in stroke patients.

Rationale for incorrect conditions
cranial nerve vii (facial nerve) controls facial expressions but not eye movement or pupil function, so it is less relevant here. cranial nerve vi (abducens nerve) controls lateral rectus muscle for lateral eye movement but does not control pupillary constriction, thus incomplete for this assessment. cranial nerve ii (optic nerve) manages visual acuity and pupillary light afferent signals but does not control eye movement or pupillary constriction efferent response, so it is insufficient alone.

Rationale for incorrect actions
assessing movement of facial expressions tests cranial nerve vii, unrelated to pupillary reflex or extraocular movement here. assessing ability to raise eyebrows is also a facial nerve function, irrelevant for eye motor or pupillary assessment. assessing visual acuity involves cranial nerve ii and does not directly reflect cranial nerve iii dysfunction.

Rationale for incorrect parameters
visual acuity monitors optic nerve function, unrelated to pupillary constriction or extraocular movement controlled by cranial nerve iii. tear production relates to facial nerve function and lacrimal glands, not relevant to oculomotor nerve assessment. taste is mediated by facial and glossopharyngeal nerves, unrelated to eye movement or pupil constriction.

Take home points

• cranial nerve iii controls most eye movements and pupillary constriction, critical in stroke assessment.
• pupillary light reflex and lateral eye movement are key clinical actions for cranial nerve iii evaluation.
• abnormal pupil size or movement indicates brainstem involvement or increased intracranial pressure.
• differentiate cranial nerve iii dysfunction from cranial nerves ii, vi, and vii for accurate neurological diagnosis.