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Eyelids
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. The human eyelid features a row of eyelashes along the eyelid margin, which serve to heighten the protection of the eye from dust and foreign debris, as well as from perspiration. "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. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levator Palpebrae Superioris Muscle
The levator palpebrae superioris ( la, elevating muscle of upper eyelid) is the muscle in the orbit that elevates the upper eyelid. Structure The levator palpebrae superioris originates from inferior surface of the lesser wing of the sphenoid bone, just above the optic foramen. It broadens and decreases in thickness (becomes thinner) and becomes the levator aponeurosis. This portion inserts on the skin of the upper eyelid, as well as the superior tarsal plate. It is a skeletal muscle. The superior tarsal muscle, a smooth muscle, is attached to the levator palpebrae superioris, and inserts on the superior tarsal plate as well. Blood supply The levator palebrae superioris receives its blood supply from branches of the ophthalmic artery, specifically, muscular branches and the supraorbital artery. Blood is drained into the superior ophthalmic vein. Nerve supply The levator palpebrae superioris receives motor innervation from the superior division of the oculomotor nerve. The smoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palpation
Palpation is the process of using one's hands to check the body, especially while perceiving/diagnosing a disease or illness. Usually performed by a health care practitioner, it is the process of feeling an object in or on the body to determine its size, shape, firmness, or location (for example, a veterinarian can feel the stomach of a pregnant animal to ensure good health and successful delivery). Palpation is an important part of the physical examination; the sense of touch is just as important in this examination as the sense of sight is. Physicians develop great skill in palpating problems below the surface of the body, becoming able to detect things that untrained persons would not. Mastery of anatomy and much practice are required to achieve a high level of skill. The concept of being able to detect or notice subtle tactile signs and to recognize their significance or implications is called appreciating them (just as in general vocabulary one can speak of appreciating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meibomian Glands
Meibomian glands (also called tarsal glands, palpebral glands, and tarsoconjunctival glands) are sebaceous glands along the rims of the eyelid inside the tarsal plate. They produce meibum, an oily substance that prevents evaporation of the eye's tear film. Meibum prevents tears from spilling onto the cheek, traps them between the oiled edge and the eyeball, and makes the closed lids airtight. There are about 25 such glands on the upper eyelid, and 20 on the lower eyelid. Dysfunctional meibomian glands is believed to be the most often cause of dry eyes. They are also the cause of posterior blepharitis. History The glands were mentioned by Galen in 200 AD and were described in more detail by Heinrich Meibom (1638–1700), a German physician, in his work ''De Vasis Palpebrarum Novis Epistola'' in 1666. This work included a drawing with the basic characteristics of the glands. Anatomy Although the upper lid have greater number and volume of meibomian glands than the lower li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Artery
The lacrimal artery is an artery of the 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, two rectus muscles of the eye, the eyelids, and the conjunctiva. Structure Origin The lacrimal artery is normally a branch of the ophthalmic artery and represents one of its largest branches. It's origin occurs near the optic canal. It usually branches off the ophthalmic artery just after the ophthalmic artery's entery into the 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 supplies the lacrimal gland, the eyelids and conjunctiva, and the superior rectus muscle a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medial Palpebral Arteries
The medial palpebral arteries (internal palpebral arteries) are arteries of the head that contribute arterial blood supply to the eyelids. They are derived from the ophthalmic artery; a single medial palpebral artery issues from the ophthalmic artery before splitting into a superior and an inferior medial palpebral artery, each supplying one eyelid. Anatomy Origin A single medial palpebral artery issues from the ophthalmic artery before bifurcating into a superior and an inferior medial palpebral artery. The origin occurs near the trochlea of the superior oblique muscle. Course The medial palpebral arteries leave the orbit to encircle the eyelids near their free margins, forming a superior and an inferior arch, which lie between the orbicularis oculi and the tarsi. Anastomoses The superior medial palpebral artery anastomoses (at lateral angle of the orbit) with the upper lateral palpebral artery, and the zygomaticoorbital branch of the temporal artery. The inferior ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Palpebral Arteries
The lateral palpebral arteries are the two large branches of those terminal branches of the lacrimal gland that supply the eyelid, with one lateral palpebral artery supplying one eyelid or the other. They pass medial-ward within the eyelid. They anastomose with medial palpebral arteries to form an arterial cricle. See also * Medial palpebral arteries The medial palpebral arteries (internal palpebral arteries) are arteries of the head that contribute arterial blood supply to the eyelids. They are derived from the ophthalmic artery; a single medial palpebral artery issues from the ophthalmic arte ... References Arteries of the head and neck {{circulatory-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anastomoses
An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (such as the foramen ovale in a fetus's heart) or abnormal (such as the patent foramen ovale in an adult's heart); it may be acquired (such as an arteriovenous fistula) or innate (such as the arteriovenous shunt of a metarteriole); and it may be natural (such as the aforementioned examples) or artificial (such as a surgical anastomosis). The reestablishment of an anastomosis that had become blocked is called a reanastomosis. Anastomoses that are abnormal, whether congenital or acquired, are often called fistulas. The term is used in medicine, biology, mycology, geology, and geography. Etymology Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Gr ana- "up, on, upon", stoma "mouth", ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infraorbital Nerve
The infraorbital nerve is a branch of the maxillary nerve, itself a branch of the trigeminal nerve (CN V). It travels through the orbit and enters the infraorbital canal to exit onto the face through the infraorbital foramen. It provides sensory innervation to the skin and mucous membranes around the middle of the face. Structure The infraorbital nerve is a branch of the maxillary nerve (CN V2), itself a branch of the trigeminal nerve (CN V). It travels with the infraorbital artery and vein. It branches from the maxillary nerve in the pterygopalatine fossa and travels through the inferior orbital fissure to enter the orbit. It runs anteriorly along the floor of the orbit in the infraorbital groove to the infraorbital canal of the maxilla. Within the infraorbital canal it has three branches, the posterior superior alveolar nerve, middle superior alveolar nerve and anterior superior alveolar nerve. After traversing the canal it emerges onto the anterior surface of the maxilla thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigeminal Nerve
In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name ("trigeminal", ) derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V), the maxillary nerve (V), and the mandibular nerve (V). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions. Adding to the complexity of this nerve is that autonomic nerve fibers as well as special sensory fibers (taste) are contained within it. The motor division of the trigeminal nerve derives from the basal plate of the embryonic pons, and the sensory division originates in the cranial neural crest. Sensory information from the face and body is proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Nerve
The lacrimal nerve is the smallest branch of the ophthalmic nerve (V1), itself a branch of the trigeminal nerve (CN V). The other branches of the ophthalmic nerve are the frontal nerve and nasociliary nerve. Structure The lacrimal nerve branches from the ophthalmic nerve immediately before traveling through the superior orbital fissure to enter the orbit. It travels through it lateral to the frontal nerve outside the annulus of Zinn. After entering, it travels anteriorly along the lateral wall with the lacrimal artery, above the upper margin of the lateral rectus. It receives a communicating branch from the zygomatic nerve which carries the postganglionic parasympathetic axons from the pterygopalatine ganglion. It travels through the lacrimal gland giving sensory and parasympathetic branches to it and then continues anteriorly as a few small sensory branches. Function The lacrimal nerve provides sensory innervation to the lacrimal gland, conjunctiva of the lateral upper eyeli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supraorbital Nerve The supraorbital nerve is one of two branches of the frontal nerve, itself a branch of the ophthalmic nerve. The other branch of the frontal nerve is the supratrochlear nerve. Structure The supraorbital nerve branches from the frontal nerve midway between the base and apex of the orbit. It travels anteriorly above the levator palpebrae superioris and exits the orbit through the supraorbital foramen (or notch) in the superior margin orbit. It exits the orbit lateral to the supratrochlear nerve. It then ascends onto the forehead beneath the corrugator supercilii and frontalis muscles and divides into a medial branch and lateral branch. Function The supraorbital nerve provides sensory innervation to the skin of the lateral forehead and upper eyelid, as well as the conjunctiva of the upper eyelid and mucosa of the frontal sinus The frontal sinuses are one of the four pairs of paranasal sinuses that are situated behind the brow ridges. Sinuses are mucosa-lined airspaces within the ... |
