Deep palpebral part of orbicularis oculi muscle

The deep palpebral part of orbicularis oculi muscle (a.k.a. the lacrimal part or tensor tarsi), is a small, thin muscular slip situated posterior to the medial palpebral ligament and lacrimal sac.

Anatomical Description

1. Origin

From the posterior lacrimal crest and the adjacent orbital surface of the lacrimal bone.

2. Course

The muscle passes medially and slightly anteriorly behind the lacrimal sac, dividing into superior and inferior slips.

3. Insertion

• The superior slip inserts into the medial end of the superior tarsus.

• The inferior slip inserts into the medial end of the inferior tarsus, both medial to the lacrimal puncta.

Innervation

Temporal and zygomatic branches of the facial nerve (cranial nerve VII).

Blood Supply

Ophthalmic artery via the dorsal nasal and medial palpebral branches.

Actions

• Draws the medial parts of the eyelids medially and posteriorly, tightening the medial palpebral ligament.

• Compresses the lacrimal sac during blinking, facilitating tear drainage into the nasolacrimal duct.

• Acts synergistically with the palpebral part to maintain smooth tear flow over the corneal surface.