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v. t. e. Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on.
The anterior segment or anterior cavity is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens. Within the anterior segment are two fluid-filled spaces: the anterior chamber between the posterior surface of the cornea (i.e. the corneal endothelium) and the iris.
Anterior part of the human eye, with label of posterior chamber at right. The posterior chamber is a narrow space behind the peripheral part of the iris, and in front of the suspensory ligament of the lens and the ciliary processes. The posterior chamber consists of small space directly posterior to the iris but anterior to the lens.
Posterior The direction toward the back of an individual's head, as opposed to anterior, which refers to the directions toward an individual's lips. The term posterior teeth refers to premolars and molars, as opposed to incisors and canines, which are anterior teeth. Proximal The surfaces of teeth that normally lie adjacent to another tooth.
In dentistry, the term anterior teeth usually refers as a group to the incisors and canine teeth as distinguished from the posterior teeth, which are the premolars and molars. The distinction is one of anterior (front of the body) versus posterior (rear of the body). The distinction holds in both the upper jaw ( maxilla) and lower jaw ( mandible ).
Rostral and caudal: In animals with linear nervous systems, the term rostral (from the Latin rostrum, meaning "beak") is synonymous with anterior and the term caudal (from the Latin cauda, meaning "tail") is synonymous with posterior. Due to humans having an upright posture, however, their nervous system is considered to bend about 90°.
Posterior cerebral circulation The anterior and posterior circulations meet at the circle of Willis, pictured here, which rests at the top of the brainstem. Inferior view. The posterior cerebral circulation is the blood supply to the posterior portion of the brain, including the occipital lobes, cerebellum and brainstem. It is supplied by the ...
Structure. The ciliary body is a ring-shaped thickening of tissue inside the eye that divides the posterior chamber from the vitreous body. It contains the ciliary muscle, vessels, and fibrous connective tissue. Folds on the inner ciliary epithelium are called ciliary processes, and these secrete aqueous humor into the posterior chamber.