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Palpebrae
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] |
Blink
Blinking is a bodily function; it is a semi-autonomic rapid closing of the eyelid. A single blink is determined by the forceful closing of the eyelid or inactivation of the levator palpebrae superioris and the activation of the palpebral portion of the orbicularis oculi, not the full open and close. It is an essential function of the eye that helps spread tears across and remove irritants from the surface of the cornea and conjunctiva. Blinking may have other functions since it occurs more often than necessary just to keep the eye lubricated. Researchers think blinking may help with disengagement of attention; following blink onset, cortical activity decreases in the dorsal network and increases in the default-mode network, associated with internal processing. Blink speed can be affected by elements such as fatigue, eye injury, medication, and disease. The blinking rate is determined by the "blinking center", but it can also be affected by external stimulus. Some animals, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmic Artery
The ophthalmic artery (OA) is an artery of the head. It is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the ophthalmic artery supply all the structures in the orbit around the eye, as well as some structures in the nose, face, and meninges. Occlusion of the ophthalmic artery or its branches can produce sight-threatening conditions. Structure The ophthalmic artery emerges from the internal carotid artery. This is usually just after the internal carotid artery emerges from the cavernous sinus. In some cases, the ophthalmic artery branches just before the internal carotid exits the cavernous sinus. The ophthalmic artery emerges along the medial side of the anterior clinoid process. It runs anteriorly, passing through the optic canal inferolaterally to the optic nerve. It can also pass superiorly to the optic nerve in a minority of cases. In the posterior third of the cone of the orbit, the ophthalmic artery turns sharply and medially t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbicularis Oculi Muscle
The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short fibrous band, the medial palpebral ligament. From this origin, the fibers are directed laterally, forming a broad and thin layer, which occupies the eyelids or palpebræ, surrounds the circumference of the orbit, and spreads over the temple, and downward on the cheek. Structure There are at least 3 clearly defined sections of the orbicularis muscle. However, it is not clear whether the lacrimal section is a separate section, or whether it is just an extension of the preseptal and pretarsal sections. Orbital orbicularis The orbital portion is thicker and of a reddish color; its fibers form a complete ellipse without interruption at the lateral palpebral commissure; the upper fibers of this portion blend with the frontalis and corrugator ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Septum
In anatomy, the orbital septum (palpebral fascia) is a membranous sheet that acts as the anterior (frontal) boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids. Structure In the upper eyelid, the orbital septum blends with the tendon of the levator palpebrae superioris, and in the lower eyelid with the tarsal plate. When the eyes are closed, the whole orbital opening is covered by the septum and tarsi. Medially it is thin, and, becoming separated from the medial palpebral ligament, attaches to the lacrimal bone at its posterior crest. The medial ligament and its much weaker lateral counterpart, attached to the septum and orbit, keep the lids stable as the eye moves. The septum is perforated by the vessels and nerves which pass from the orbital cavity to the face and scalp. Clinical significance Orbital septum supports the orbital contents located posterior to it, especially orbital fat. The septum can be weakene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supratrochlear
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 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 is smaller than the supraorbital nerve from the frontal nerve. It branches midway between the base and apex of the orbit. It passes above the trochlea of the superior oblique muscle. It then travels anteriorly above the levator palpebrae superioris muscle. It exits the orbit through the frontal notch in the superomedial margin of the orbit. It then ascends onto the forehead beneath the corrugator supercilii muscle and frontalis muscle. It then divides into sensory branches. The supratrochlear nerve travels with the supratrochlear artery, a branch of the ophthalmic artery. Function The supratrochlear ner ... [...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 ... [...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] |
Infratrochlear
The infratrochlear nerve is a branch of the nasociliary nerve, itself a branch of the ophthalmic nerve. 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. Function The infratrochlear nerve provides sensory innervation to the skin of the eye lids, the conjunctiva, lacrimal sac, lacrimal caruncle and the side of the nose above the medial canthus. Etymology The infratrochlear nerve is named after a structure it passes under. ''Infratrochlear'' means "below the trochlea Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel. Related to joints Most commonly, trochleae bear the articular surface of saddle joint, saddle ... [...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] |
Encyclopædia Britannica Ultimate Reference Suite
''Encyclopædia Britannica Ultimate Reference Suite'' is an encyclopaedia based on the ''Encyclopædia Britannica'' and published by Encyclopædia Britannica, Inc. It was published between 2003 and 2015. Product description The DVD contains over 100,000 articles, an atlas, around 35,000 media files (images, video and Audio file format, audio) and a dictionary and thesaurus based on Merriam-Webster. Awards ''Encyclopædia Britannica Ultimate Reference Suite'' received the 2004 Distinguished Achievement Award from the Association of Educational Publishers. Its predecessor, ''Britannica'' DVD, received Codie awards in 2000, 2001 and 2002. Linux support There is no official release of ''Britannica'' for the Linux, Linux operating system; however, a script is provided that can help experienced users run ''Encyclopædia Britannica 2004 Ultimate Reference Suite'' DVD (and other 2004 editions of ''Britannica'') on Linux, with some limitations (for example the dictionary, Flash/Quic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
