The Palpebral Reflex

Clinical Exam

Both the medial and lateral canthus of each eye is touched with the finger and in response there should be a rapid and complete closure of the eyelids.

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Anatomic Pathway

In this animation, both medial and lateral stimulation of the eyelids can be seen to result in a sensory impulse traveling into the brainstem via the trigeminal nerve. This results in ipsilateral stimulation of the facial nerve (CN VII) which closes the eye lids due to contraction of the orbicularis oculi muscles. The brainstem can also be seen to give rise to a pathway travelling to the contralateral cortex which is responsible for conscious perception of touch.

Overview of Anatomy

Touching the medial canthus of the palpebral fissure stimulates the ophthalmic branch of the trigeminal nerve which runs into the skull through the orbital fissure and once inside the brainstem triggers a motor response via the facial nerve. This results in contraction of the orbicularis oculi closing the eyelids.

Touching the lateral canthus of the palpebral fissure stimulates the maxillary branch of the trigeminal nerve which runs in to the skull through the rostral alar foramen, the alar canal and the round foramen. Once inside the brainstem, this stimulus triggers a motor response via the facial nerve. This results in contraction of the orbicularis oculi closing the eyelids

Anatomic Sections

Stimulation of the skin around the eye leads to a trigeminal nerve impulse via the maxillary and ophthalmic branches; this can be seen to cause a reflex closure of the eyelids following interneuron activity within the brainstem leading to facial nerve stimulation.