|
Conjunctiva
In the anatomy of the eye, the conjunctiva (: conjunctivae) is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium and stratified cuboidal epithelium (depending on the zone). The conjunctiva is highly Angiogenesis, vascularised, with many microvessels easily accessible for imaging studies. Structure The conjunctiva is typically divided into three parts: Blood supply Blood to the bulbar conjunctiva is primarily derived from the ophthalmic artery. The blood supply to the palpebral conjunctiva (the eyelid) is derived from the external carotid artery. However, the circulations of the bulbar conjunctiva and palpebral conjunctiva are linked, so both bulbar conjunctival and palpebral conjunctival vessels are supplied by both the ophthalmic artery and the external carotid artery, to varying extents. Nerve supply Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Artery
The lacrimal artery is an artery of the Orbit (anatomy), orbit. It is a branch of the ophthalmic artery. It accompanies the lacrimal nerve along the upper border of the lateral rectus muscle, travelling forward to reach the lacrimal gland. It supplies the lacrimal gland, as well as Extraocular muscles, two rectus muscles of the eye, the Eyelid, eyelids, and the conjunctiva. Structure Origin The lacrimal artery is normally a branch of the ophthalmic artery and represents one of its largest branches. Its origin occurs near the optic foramen, optic canal. It usually branches off the ophthalmic artery just after the ophthalmic artery's entry into the Orbit (anatomy), orbit. It can rarely arise before the ophthalmic artery enters the optic canal. Course and relations The lacrimal artery accompanies the lacrimal nerve along the upper border of the lateral rectus muscle. It travels anterior-ward to supply the lacrimal gland. Branches and distribution The lacrimal artery suppli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Ciliary Arteries
The anterior ciliary arteries are seven arteries in each eye-socket that arise from muscular branches of the ophthalmic artery and supply the conjunctiva, sclera, rectus muscles, and the ciliary body. The arteries end by anastomosing with branches of the long posterior ciliary arteries to form the circulus arteriosus major. Anatomy There are seven anterior ciliary arteries on each side of the body; two anterior ciliary arteries are associated with the superior, the medial, and the inferior rectus muscles, whereas the lateral rectus muscle is associated with only a single anterior ciliary artery. Origin The anterior ciliary arteries arise from muscular branches of the ophthalmic artery supplying the rectus muscles of the eye. Course and relations The anterior ciliary arteries exit the muscles near the muscles' insertions, passing anterior-ward alongside the rectus muscles' tendons before turning inward to perforate the sclera near the corneal limbus to reach the ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Nerve
The lacrimal nerve is the smallest of the three main branches of the ophthalmic nerve (CN V1) (itself a branch of the trigeminal nerve (CN V)). It enters the orbit outside the common tendinous ring and passes forward along the side wall of the orbit. It provides sensory innervation to the skin and both surfaces of conjunctiva at the lateral portion of the upper eyelid. It also receives a parasympathetic secretomotor communicating branch for the lacrimal gland which it conveys to the gland. Structure Origin The lacrimal nerve branches from the ophthalmic nerve immediately before traveling through the superior orbital fissure to enter the orbit. At the superior portion of the lateral wall of the orbit, it also receives a secretomotor communicating parasympathetic branch from the zygomaticotemporal nerve for the lacrimal gland. Course It enters the orbit through the superior orbital fissure outside (lateral to) the common tendinous ring, coursing lateral to the front ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tenon's Capsule
Tenon's capsule (), also known as the Tenon capsule, fascial sheath of the eyeball () or the fascia bulbi, is a thin membrane which envelops the eyeball from the optic nerve to the corneal limbus, separating it from the orbital fat and forming a socket in which it moves. The inner surface of Tenon's capsule is smooth and is separated from the outer surface of the sclera by the periscleral lymph space. This lymph space is continuous with the subdural and subarachnoid cavities and is traversed by delicate bands of connective tissue which extend between the capsule and the sclera. The capsule is perforated behind by the ciliary vessels and nerves and fuses with the sheath of the optic nerve and with the sclera around the entrance of the optic nerve. In front it adheres to the conjunctiva, and both structures are attached to the ciliary region of the eyeball. The structure was named after Jacques-René Tenon (1724–1816), a French surgeon and pathologist. Structure Relations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyelid
An eyelid ( ) is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. "Palpebral" (and "blepharal") means relating to the eyelids. Its key function is to regularly spread the tears and other secretions on the eye surface to keep it moist, since the cornea must be continuously moist. They keep the eyes from drying out when asleep. Moreover, the blink reflex protects the eye from foreign bodies. A set of specialized hairs known as lashes grow from the upper and lower eyelid margins to further protect the eye from dust and debris. The appearance of the human upper eyelid often varies between different populations. The prevalence of an epicanthic fold covering the inner corner of the eye account for the majority of East Asian and Southeast Asian populations, and is also found in varying degrees among other populat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goblet Cell
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 2 in the lower gastrointestinal tract, and mucin 5AC in the respiratory tract. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secretions, when under stress. The term '' goblet'' refers to the cell's goblet-like shape. The apical portion is shaped like a cup, as it is distended by abundant mucus laden granules; its basal portion lacks these granules and is shaped like a stem. The goblet cell is highly polarized with the nucleus and other organelles concentrated at the base of the cell and secretory granules containing mucin, at the apical surface. The apical plasma membrane projects short microvilli to give an increased surface area for secretion. Goblet cells are typically found in the respiratory, reproductive and lower gastrointestinal tract and are surrounded by other columnar cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goblet Cells
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 2 in the lower gastrointestinal tract, and mucin 5AC in the respiratory tract. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secretions, when under stress. The term ''goblet'' refers to the cell's goblet-like shape. The apical portion is shaped like a cup, as it is distended by abundant mucus laden granules; its basal portion lacks these granules and is shaped like a stem. The goblet cell is highly polarized with the nucleus and other organelles concentrated at the base of the cell and secretory granules containing mucin, at the apical surface. The apical plasma membrane projects short microvilli to give an increased surface area for secretion. Goblet cells are typically found in the respiratory, reproductive and lower gastrointestinal tract and are surrounded by other columnar cells. Bia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infratrochlear Nerve
The infratrochlear nerve is a branch of the nasociliary nerve (itself a branch of the ophthalmic nerve (CN V1)) in the orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an .... It exits the orbit inferior to the trochlea of superior oblique. It provides sensory innervation to structures of the orbit and skin of adjacent structures. Structure The nasociliary nerve terminates by bifurcating into the infratrochlear and the anterior ethmoidal nerves. The infratrochlear nerve travels anteriorly in the orbit along the upper border of the medial rectus muscle and underneath the trochlea of the superior oblique muscle. It exits the orbit medially and divides into small sensory branches. Distribution The infratrochlear nerve provides sensory innervation to the skin of the eyelids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supraorbital Nerve
The supraorbital nerve is one of two terminal branches - the other being the supratrochlear nerve - of the frontal nerve (itself a branch of the ophthalmic nerve (CN V1)). It exits the orbit via the supraorbital foramen/notch before splitting into a medial branch and a lateral branch. It innervates the skin of the forehead, upper eyelid, and the root of the nose. Structure Origin The supraorbital nerve branches from the frontal nerve midway between the base and apex of the orbit. Course It travels anteriorly superior to the levator palpebrae superioris muscle. It exits the orbit through the supraorbital foramen/notch in the superior margin orbit, exiting it lateral to the supratrochlear nerve. It then ascends onto the forehead deep to the corrugator supercilii muscle and frontalis muscles. Fate It divides into a medial branch and lateral branch - usually after emerging from the orbit, but sometimes already within the orbit. Distribution The supraorbital nerv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratified Columnar Epithelium
Stratified columnar epithelium is a rare type of epithelial tissue composed of column-shaped cells arranged in multiple layers. It is found in the conjunctiva, pharynx, anus, and male urethra. It also occurs in embryo. Location Stratified columnar epithelia are found in a variety of locations, including: * parts of the conjunctiva of the eye * parts of the pharynx * anus * male urethra and vas deferens * excretory duct of mammary gland and major salivary glands Embryology Stratified columnar epithelium is initially present in parts of the gastrointestinal tract in utero, before being replaced with other types of epithelium. For example, by 8 weeks, it covers the lining of the stomach. By 17 weeks, it is replaced by simple columnar epithelium. This is also found in the fetal esophagus. Function The cells function in secretion Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accessory Lacrimal Glands
Krause's glands and Wolfring's glands (or Ciaccio's glands) are the accessory lacrimal glands of the lacrimal system of human eye. These glands are structurally and histologically similar to the Lacrimal gland, main lacrimal gland. Glands of Krause are located in the stroma of the conjunctival fornix, and the glands of Wolfring are located along the orbital border of the tarsal plate. These glands are oval and display numerous acini. The acini are surrounded, sometimes incompletely, by a row of myoepithelial cells. Animal studies suggest that the ducts of Wolfring glands have a tortuous course and open onto the palpebral conjunctiva. Like the main lacrimal gland, the accessory lacrimal glands are also densely innervated, but they lack parasympathetic innervation. These glands are exocrine glands, responsible for the basal (unstimulated) secretion of the middle aqueous layer of the Tears, tear film. 20 to 40 glands of Krause are found in the upper fornix, and 6-8 glands appear in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supratrochlear Nerve
The supratrochlear nerve is a branch of the frontal nerve, itself a branch of the ophthalmic nerve (CN V1) from the trigeminal nerve (CN V). It provides sensory innervation to the skin of the forehead and the upper eyelid. Structure Origin The supratrochlear nerve is the smaller of the two terminal branches of the frontal nerve (the other being the supraorbital nerve). It arises midway between the base and apex of the orbit where the frontal nerve splits into said terminal branches. Course The supratrochlear nerve passes medially above the trochlea of the superior oblique muscle. It then travels anteriorly above the levator palpebrae superioris muscle. It exits the orbit through the supratrochlear notch or foramen. It then ascends onto the forehead beneath the corrugator supercilii muscle and frontalis muscle. It finally divides into sensory branches. The supratrochlear nerve travels with the supratrochlear artery, a branch of the ophthalmic artery. Branches Be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
