Orbicularis Oculi

Description

Lateral profile anatomy frames the orbit and midface, with the orbicularis oculi highlighted as a circumferential sphincter around the palpebral fissure. The palpebral part lies superficial to the tarsal plates of the upper and lower eyelids, while the thicker orbital part extends beyond the orbital rim onto the frontal process of the maxilla and zygomatic bone, blending laterally near the lateral palpebral raphe. Deep to the muscle ring sit the bony margins of the orbit and adjacent nasal skeleton, with the maxilla and mandible inferiorly, the auricle posteriorly, and the cervical spine and hyoid bone descending into the upper neck. Functionally, this view clarifies how eyelid closure depends on facial nerve (CN VII) motor input and how subtle differences between the palpebral and orbital fibers map to clinical findings: gentle blinking and lacrimal pump activity versus forceful closure during photophobia or irritation. Weakness of orbicularis oculi after Bell palsy, iatrogenic CN VII injury, or periorbital trauma produces lagophthalmos and exposure keratopathy, while hyperactivity appears in blepharospasm and is a common target for botulinum toxin injection around the lateral orbital rim. Surface relationships to the nasal sidewall and zygoma help orient periocular surgical planning, including lower blepharoplasty and repair of eyelid lacerations where the muscle fibers can be reapproximated to restore blink mechanics. Small muscle, big consequences. Use this illustration in head and neck anatomy teaching, oculoplastics and ENT educational material, and clinical communications explaining facial nerve palsy, eyelid closure deficits, or planned chemodenervation patterns for blepharospasm. It also supports textbook figures that tie facial expression muscles to craniofacial osteology in a single lateral plate. Anatomical accuracy verified by SciePro's Medical Advisory Board.