What Is a Palpebral Fissure?

Eyelid fissure: The position of the space between the upper and lower eyelid edges when the eyelid is opened, simply the gap between the upper and lower eyelid edges. In normal children, the upper eyelid margin reaches the upper level of the cornea when viewed horizontally; in children, the upper and lower edges of the cornea are symmetrically covered by 1 millimeter; in adults, the upper eyelid margin covers the upper edge of the cornea by 1 to 2 millimeters. The lower edge is in contact with the lower eyelid edge. The average length of palpebral fissures in China is 27.88 mm for adults, 28.30 mm for men, and 27.14 mm for women. The average height of palpebral fissures is 7.54 mm, 7.66 mm for men, and 7.24 mm for women.

Eyelid fissure: The position of the space between the upper and lower eyelid edges when the eyelid is opened, simply the gap between the upper and lower eyelid edges. In normal children, the upper eyelid margin reaches the upper level of the cornea when viewed horizontally; in children, the upper and lower edges of the cornea are symmetrically covered by 1 millimeter; in adults, the upper eyelid margin covers the upper edge of the cornea by 1 to 2 millimeters. The lower edge is in contact with the lower eyelid edge. The average length of palpebral fissures in China is 27.88 mm for adults, 28.30 mm for men, and 27.14 mm for women. The average height of palpebral fissures is 7.54 mm, 7.66 mm for men, and 7.24 mm for women.

Chinese name

palpebral fissure

Foreign name

palpebral fissure

Pinyin

jinliè

Reference

Oral Anatomy and Physiology

Blepharoplasty, eyelid

The eyelid is located in front of the eyeball, divided into upper and lower eyelids, and the crack between the eyelids is called blepharoplasty. The eyelid is composed of skin, connective tissue, muscle, glands and conjunctiva, and is an important structure to protect the eyeball. The free edge of the eyelid is called the eyelid edge, which is the junction of the skin and the mucous membrane. There are 2 to 3 rows of eyelashes, and there are gland openings.

The structure of the eyelid: The eyelid consists of four layers: skin, muscle layer, fibrous layer, and conjunctiva.

Skin: Thin and soft, prone to wrinkles. The epidermis is thin, with a few nipples protruding from the dermis to the epidermis. There are fine hair, sebaceous glands and sweat glands. The dermis is denser near the edge of the eyelid and has high nipples. The subcutaneous tissue is loose and rich in fine elastic fibers, and the yellow people have very little adipose tissue. The edge of the eyelid has 3 to 4 rows of thick hairs obliquely growing, called eyelashes. These hairs have no fluffy muscles and have sebaceous glands called Zeis glands that open into the hair follicles. The eyelashes are changed every 100 to 150 days. There is a special sweat gland, called the eyelash gland or Moll gland, between or behind the eyelash follicles. This gland consists of a secretory part and a duct. The secretory part is straight or slightly curved, and the lumen is large. It consists of flattened cubic glandular cells and myoepithelial cells. The catheter is thin, the wall of the tube is formed from two layers of epithelial cells, and it opens into the eyelash follicles. The structural characteristics of this gland are apocrine secretion of sweat glands, and the nature of the secretion is unknown.

Muscle layer: Mainly the orbicularis orbicularis, which belongs to the skeletal muscle, is arranged in the circumcision of the eyelid. The orbicularis muscle is innervated by the facial nerve, and the palpebral fissure opens and closes. The upper eyelid also has the levator muscle and its aponeurosis, which are interspersed between the orbicularis oris and the meibomian plate. It is dominated by the eye nerve and can raise the upper eyelid. In addition, the upper eyelid muscle and lower eyelid muscle that extend from the vicinity of the extraocular muscles and extend into the eyelid conjunctiva and between the meibomian and lower edges, also known as Müller muscle, are smooth muscles that are dominated by the cervical sympathetic nerve. Open up.

Fibrous layer: composed of meibomian and orbital septum. The eyelid plate is a plate made of dense connective tissue. The upper eyelid is 10-12mm wide and the lower eyelid is 5mm wide. It is a supporting structure of the eyelid. The meibomian glands, or Meibom glands, are buried in the meibomians and arranged in parallel rows. They have the structural features of sebaceous glands (see "Sebaceous Glands"). There are 30 to 40 upper eyelids and 20 to 30 lower eyelids. Each gland has multiple secretions, which are connected to the main duct by short ducts. The main ducts of each gland open in rows at the inner edge of the eyelid. This glandular secretion contains cholesterol esters and esters, forming the surface layer of the tear film, which has the effect of moistening the cornea and smoothing the eyelid margin. The orbital septum is a dense connective tissue between the orbital periosteal membrane and the meibomian plate, which can block the orbital fat tissue from entering the eyelid and prevent the inflammation from spreading.

Eyelid conjunctiva: Cover the inner surface of the eyelid, close to the eyelid, and cannot move. Normally, this membrane is smooth and transparent, rich in blood vessels, and pale red. The epithelium is a stratified columnar epithelium that begins at the posterior edge of the meibomian gland opening and has goblet cells. The lamina propria is denser connective tissue, and macrophages, lymphocytes, and mast cells are common. The lamina propria is not tightly connected with the fatty tissue in the orbit, allowing the eyeball to move freely in the conjunctival sac. The conjunctiva of the fornix is refolded and attached to the outside of the sclera to form a bulbous conjunctiva. The conjunctival meniscus is equivalent to the transient membrane of lower vertebrates. It is a fold formed by the bulbar conjunctiva on the inner side of the eyelid and the outer side of the lacrimal fungus. There are many goblet cells in the epithelium outside the half moon crest.

Blood vessels and nerves of the eyelid: The arteries mainly come from the branches of the ophthalmic artery, which are called the medial superior and inferior arteries, and the lateral superior and inferior arteries. The veins flow into the internal iliac vein (medial) and superficial temporal vein (lateral). The sensory nerve of the eyelid is a branch of the trigeminal nerve-the eye nerve and the maxillary nerve. The motor nerve is dominated and raised. The oculomotor nerve branch of the muscle and the facial nerve branch that dominates the orbicularis muscle. There are branches of the cervical sympathetic nerve that innervate Muller muscles, blood vessels, and glands.