Orbicularis oculi muscle

Orbicularis oculi are facial muscles, a ring-like muscle functioning in a number of eyelid movements.

Gross anatomy

The orbicularis oculi are made up of three parts the orbital, palpebral and lacrimal parts. Each has defined actions. 

The orbicularis oculi are secured to the medial and lateral palpebral ligament forming a ring in the eyelid tissue centred about the anterior eye. It also inserts on the eyelid 'skeleton' the tarsal plate. It forms connections with the superficial muscular aponeurotic system (SMAS) of the face to frontalis, the temple and the cheek. 

Laterally the fibres are pierced by the zygomaticofacial nerve which supplies the skin over the zygoma.

Orbital part

The orbital part forms the bulk of the muscle, can squeeze the eyelid closed tightly and is used in bright light.

Palpebral part

Has thinner fibres continuous with the orbital part. It functions to lightly close the eyelid. 

Lacrimal part

Forms a small slip originating adjacent to the lacrimal gland to insert on the lateral eyelid. It is thought to promote flow within the gland.