Orbicularis Oculi Muscle (Left)

Origin

The orbicularis oculi muscle is a broad, flat muscle that encircles the orbit, thus forming a sphincter around each of the eye sockets. It may be divided into three portions:

- orbital part;

- palpebral part;

- lacrimal part.

The orbital part of the orbicularis oculi muscle originates from the nasal part of the frontal bone, the frontal process of maxilla, and the medial palpebral ligament. The palpebral part originates from the medial palpebral ligament, while the lacrimal part arises from the posterior lacrimal crest of the lacrimal bone.

Insertion

The orbital part of the orbicularis oculi muscle encircles the orbit and its fibers blend with adjacent muscles. The fibers of the palpebral part intertwine forming the lateral palpebral raphe, with bulk of its fibers located within the eyelid. The majority of the fibers from lacrimal part insert into the lateral palpebral raphe (Standring, 2016).

Actions

The orbital part of the orbicularis oculi muscle closes the eyelids, while the palpebral part gently closes the eyelid, for example when blinking. The lacrimal portion of orbicularis oculi muscle draws the eyelids medially which is thought to aid in tear drainage by compressing the lacrimal sac (Standring, 2016).

List of Clinical Correlates

- Bell’s palsy

- Lagophthalmos

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.