orbital part
Last reviewed 01/2018
The orbital part of orbicularis oculi is the outermost of the three parts around the orbit. From superior to inferior, it arises from the:
- nasal part of the frontal bone
- medial palpebral ligament
- frontal process of the maxilla
Its fibres diverge from these origins to pass around the orbit as a complete, uninterrupted ellipse. Throughout this coure, the muscle fibres surround the palpebral part of the muscle.
The upper fibres of the orbital part of the muscle intermingle with fibres from two other muscles: occipitofrontalis and corrugator supercilii. Also, they insert into the deep surface of the skin beneath the eyebrow.
The blood supply to the muscle derives from the ophthalmic, zygomatico-orbital and angular arteries.
It is innervated by fibres from the facial nerve (VII) via the zygomatic and frontal branches.
The orbital portion of orbicularis oculi is under more voluntary control than the palpebral or tarsal parts; it is involved in the willed, forced closure of the eye.