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Annulus Of Zinn
The common tendinous ring, also known as the annulus of Zinn, or annular tendon, is a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit. It is the common origin of the four recti muscles of the group of extraocular muscles. It can be used to divide the regions of the superior orbital fissure. The arteries surrounding the optic nerve form a vascular structure known as the circle of Zinn-Haller, or sometimes as the ''circle of Zinn''. The following structures pass through the tendinous ring (superior to inferior): * Superior division of the oculomotor nerve (CNIII) * Nasociliary nerve (branch of ophthalmic nerve) * Inferior division of the oculomotor nerve (CNIII) * Abducens nerve (CNVI) * Optic nerve Parts The common tendinous ring spans the superior orbital fissure and can be described as having two parts – an inferior tendon which gives origin to the inferior rectus muscle, and to part of the lateral rectus muscle; and a superi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Rectus Muscle
The superior rectus muscle is a muscle in the orbit. It is one of the extraocular muscles. It is innervated by the superior division of the oculomotor nerve (III). In the primary position (looking straight ahead), its primary function is elevation, although it also contributes to intorsion and adduction. It is associated with a number of medical conditions, and may be weak, paralysed, overreactive, or even congenitally absent in some people. Structure The superior rectus muscle originates from the annulus of Zinn. It inserts into the anterosuperior surface of the eye. This insertion has a width of around 11 mm. It is around 8 mm from the corneal limbus. Nerve supply The superior rectus muscle is supplied by the superior division of the oculomotor nerve (III). Relations The superior rectus muscle is related to the other extraocular muscles, particularly to the medial rectus muscle and the lateral rectus muscle. The insertion of the superior rectus muscle is around 7.5 mm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraocular Muscles
The extraocular muscles (extrinsic ocular muscles), are the seven extrinsic muscles of the human eye. Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye and the other muscle, the levator palpebrae superioris, controls eyelid elevation. The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction. Structure Since only a small part of the eye called the fovea provides sharp vision, the eye must move to follow a target. Eye movements must be precise and fast. This is seen in scenarios like reading, where the reader must shift gaze constantly. Although under voluntary control, most eye movement is accomplished without conscious effort. Precisely how the integration between voluntary and involuntary control of the eye occurs is a subject of continuing research."eye, human."Encyclopædia Britannica from Encyclopædia Britannica 2006 Ulti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zonule Of Zinn
The zonule of Zinn () (Zinn's membrane, ciliary zonule) (after Johann Gottfried Zinn) is a ring of fibrous strands forming a zonule (little band) that connects the ciliary body with the crystalline lens of the eye. These fibers are sometimes collectively referred to as the suspensory ligaments of the lens, as they act like suspensory ligaments. Development The ciliary epithelial cells of the eye probably synthesize portions of the zonules. Anatomy The zonule of Zinn is split into two layers: a thin layer, which lines the hyaloid fossa, and a thicker layer, which is a collection of zonular fibers. Together, the fibers are known as the suspensory ligament of the lens. The zonules are about 1–2 μm in diameter. The zonules attach to the lens capsule 2 mm anterior and 1 mm posterior to the equator, and arise of the ciliary epithelium from the pars plana region as well as from the valleys between the ciliary processes in the pars plicata. When colour granules are displaced from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Gottfried Zinn
Johann Gottfried Zinn () (December 6, 1727 – April 6, 1759) was a German anatomist and botanist and was a member of the Berlin Academy. Biography Johann Gottfried Zinn was born in Schwabach. Considering his short life span, Zinn made a great contribution to the study of anatomy. In his book ''Descriptio anatomica oculi humani'', he provided the first detailed and comprehensive anatomy of the human eye. In 1753 Johann Gottfried Zinn became director of the Botanic garden of the University of Göttingen, and in 1755, professor in the medical faculty. In 1757 Zinn described the orchid genus ''Epipactis'' that belongs to the family Orchidaceae. He died in Göttingen. Eponyms Botanist Carl Linnaeus designated a genus of flowers in the family Asteraceae native from Mexico as ''Zinnia'' in his honour. He coined the anatomic terms: * ''Zonula ciliaris Zinnii'', now called ''Zonule of Zinn'' * ''Anulus tendineus communis'' also known as ''Annulus of Zinn The common tendinous r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abducens Nerve
The abducens nerve or abducent nerve, also known as the sixth cranial nerve, cranial nerve VI, or simply CN VI, is a cranial nerve in humans and various other animals that controls the movement of the lateral rectus muscle, one of the extraocular muscles responsible for outward gaze. It is a somatic efferent nerve. Structure Nucleus The abducens nucleus is located in the pons, on the floor of the fourth ventricle, at the level of the facial colliculus. Axons from the facial nerve loop around the abducens nucleus, creating a slight bulge (the facial colliculus) that is visible on the dorsal surface of the floor of the fourth ventricle. The abducens nucleus is close to the midline, like the other motor nuclei that control eye movements (the oculomotor and trochlear nuclei). Motor axons leaving the abducens nucleus run ventrally and caudally through the pons. They pass lateral to the corticospinal tract (which runs longitudinally through the pons at this level) before exiting t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmic Nerve
The ophthalmic nerve (V1) is a sensory nerve of the face. It is one of three divisions of the trigeminal nerve (CN V). It has three branches that provide sensory innervation to the eye, the skin of the upper face, and the skin of the anterior scalp. Structure The ophthalmic nerve is the first branch of the trigeminal nerve (CN V). It is joined by filaments from the cavernous plexus of the sympathetic, and communicates with the oculomotor, trochlear, and abducent nerves. It gives off a recurrent (meningeal) filament which passes between the layers of the tentorium. Branches The ophthalmic nerve divides into three major branches as it passes through the superior orbital fissure. *The nasociliary nerve gives off several sensory branches to the orbit. It then continues out through the anterior ethmoidal foramen, where it enters the nasal cavity. It provides innervation for much of the anterior nasal mucosa. It also gives off a branch which exits through the nasal bones to form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasociliary Nerve
The nasociliary nerve is a branch of the ophthalmic nerve, itself a branch of the trigeminal nerve (CN V). It is intermediate in size between the other two branches of the ophthalmic nerve, the frontal nerve and lacrimal nerve. Structure The nasociliary nerve enters the orbit via the superior orbital fissure, between the two heads of the lateral rectus muscle and between the superior and inferior rami of the oculomotor nerve. It passes across the optic nerve (CN II) and runs obliquely beneath the superior rectus muscle and superior oblique muscle to the medial wall of the orbital cavity. It passes through the anterior ethmoidal opening as the anterior ethmoidal nerve and enters the cranial cavity just below the cribriform plate of the ethmoid bone. It supplies branches to the mucous membrane of the nasal cavity and finally emerges between the inferior border of the nasal bone and the side nasal cartilages as the external nasal branch. Branches * posterior ethmoidal nerve * ante ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oculomotor Nerve
The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of the eye and that raise the eyelid. The nerve also contains fibers that innervate the intrinsic eye muscles that enable pupillary constriction and accommodation (ability to focus on near objects as in reading). The oculomotor nerve is derived from the basal plate of the embryonic midbrain. Cranial nerves IV and VI also participate in control of eye movement. Structure The oculomotor nerve originates from the third nerve nucleus at the level of the superior colliculus in the midbrain. The third nerve nucleus is located ventral to the cerebral aqueduct, on the pre-aqueductal grey matter. The fibers from the two third nerve nuclei located laterally on either side of the cerebral aqueduct then pass through the red nucleus. From the red nuc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circle Of Zinn-Haller
The short posterior ciliary arteries, around twenty in number, arise from the medial posterior ciliary artery and lateral posterior ciliary artery, which are branches of the ophthalmic artery as it crosses the optic nerve. Course and target They pass forward around the optic nerve to the posterior part of the eyeball, pierce the sclera around the entrance of the optic nerve, and supply the choroid (up to the equator of the eye) and ciliary processes. Some branches of the short posterior ciliary arteries also supply the optic disc via an anastomotic ring, the circle of Zinn-Haller or ''circle of Zinn'', which is associated with the fibrous extension of the ocular tendons (common tendinous ring (also annulus of Zinn)). Additional images File:Gray880.png, The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section See also * Long posterior ciliary arteries *Anterior ciliary arteries The anterior ciliary arteries are seven small arteries in ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pulmonary and the umbilical arteries, which carry deoxygenated blood to the organs that oxygenate it (lungs and placenta, respectively). The effective arterial blood volume is that extracellular fluid which fills the arterial system. The arteries are part of the circulatory system, that is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products, the maintenance of optimum blood pH, and the circulation of proteins and cells of the immune system. Arteries contrast with veins, which carry blood back towards the heart. Structure The anatomy of arteries can be separated into gross anatomy, at the macroscopic level, and microanatomy, which must be studied with a microscop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Orbital Fissure
The superior orbital fissure is a foramen or cleft of the skull between the lesser and greater wings of the sphenoid bone. It gives passage to multiple structures, including the oculomotor nerve, trochlear nerve, ophthalmic nerve, abducens nerve, ophthalmic veins, and sympathetic fibres from the cavernous plexus. Structure The superior orbital fissure is usually 22 mm wide in adults, and is much larger medially. Its boundaries are formed by the (caudal surface of the) lesser wing of the sphenoid bone, and (medial border of the) greater wing of the sphenoid bone. Contents The superior orbital fissure is traversed by the following structures: * (superior and inferior divisions of the) oculomotor nerve (CN III) * trochlear nerve (CN IV) * lacrimal, frontal, and nasociliary branches of ophthalmic nerve (CN V1) * abducens nerve (CN VI) * superior ophthalmic vein and superior division of the inferior ophthalmic vein * sympathetic fibres from the cavernous nerve pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraocular Muscles
The extraocular muscles (extrinsic ocular muscles), are the seven extrinsic muscles of the human eye. Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye and the other muscle, the levator palpebrae superioris, controls eyelid elevation. The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction. Structure Since only a small part of the eye called the fovea provides sharp vision, the eye must move to follow a target. Eye movements must be precise and fast. This is seen in scenarios like reading, where the reader must shift gaze constantly. Although under voluntary control, most eye movement is accomplished without conscious effort. Precisely how the integration between voluntary and involuntary control of the eye occurs is a subject of continuing research."eye, human."Encyclopædia Britannica from Encyclopædia Britannica 2006 Ulti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
