Eye lids

Overview

The eyelids act to protect the anterior surface of the globe from local injury. Additionally, they aid in the regulation of light reaching the eye; in tear film maintenance, by distributing the protective and optically important tear film over the cornea during blinking; and in tear flow, by their pumping action on the conjunctival sac and lacrimal sac.

Structures that must be considered in a description of lid anatomy are the skin and subcutaneous tissue; the orbicularis oculi muscle (shown below); the submuscular areolar tissue; the fibrous layer, consisting of the tarsi and the orbital septum; the lid retractors of the upper and lower eyelids; the retroseptal fat pads; and the conjunctiva.

Orbicularis oculi muscle anatomy. (A) Frontalis, (B) corrugator superciliaris, (C) procerus, (D) orbital orbicularis, (E) preseptal orbicularis, (F) pretarsal orbicularis.

Source Medscape

Mcq Point

MOTOR

The closing of the eyelid by orbicularis oculi muscle (7)

Opening by elevator (3) and Muller ( sympathetic) Muscle

Sensory

Upper LID

Supratrochlear
Infratrochlear
Supraorbital
Lacrimal

Lower LID

Lacrimal
infraorbital
infratrochlear

Surface Anatomy

The upper eyelid extends superiorly to the eyebrow, which separates it from the forehead. The lower lid extends below the inferior orbital rim to join the cheek, forming folds where the loose connective tissue of the eyelid is juxtaposed with the denser tissue of the cheek. (See the images below.)

The eyelids are designed to protect, nourish and sustain the cornea and the anterior sclera. Anatomically, the eyelid is divided into 2 lamellae, anterior and posterior, demarcated by the gray line. The anterior lamella is composed of the epithelium and orbicularis oculi, whereas the tarsus and palpebral conjunctiva form the posterior lamella.

The arrangement of the Eyelid layers

Fibrous layer contain tarsal plate and meibomian gland
Injections are given in submuscular areolar layer
Lower lid sensory supply si maxillary
Striated muscle Layer contains Orbicularis muscle while behind the tarsal plate there is levator muscle aponeurosis then followed by nonstriated muscle layer containing muller muscle
Glands of Zeis are sebaceous and Meibomian glands are modified sebaceous and are located in between tarsal layer
Glands of Moll are ciliary sweat glands