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Any of several anatomic structures with numerous intercommunicating cells or canals. 1. The internal or inner ear, composed of the semicircular ducts, vestibule, and cochlea. 2. Any group of communicating cavities, as in each lateral mass of the ethmoid bone. 3. A group of upright test tubes terminating below in a base of communicating, alternately ∪-shaped and ∩-shaped tubes, used for isolating motile from nonmotile organisms in culture, or a motile from a less motile organism (as the typhoid from the colon bacillus), the former traveling faster and farther through the tubes than the latter.
- bony l. [TA] a series of cavities (cochlea, vestibule, and semicircular canals) contained within the otic capsule of the petrous portion of the temporal bone; the bony l. is filled with perilymph, in which the delicate, endolymph-filled membranous l. is suspended. SYN: labyrinthus osseus [TA], osseous l..
- cochlear l. [TA] the portion of the membranous l. concerned with the sense of hearing (vs. the vestibular l., which is concerned with the sense of equilibration) and innervated by the cochlear nerve; it is located within the cochlea of the bony l., and consists of the cochlear duct, which contains the spiral organ. SYN: labyrinthus cochlearis [TA], organ of hearing.
- ethmoidal l. [TA] a mass of air cells with thin bony walls forming part of the lateral wall of the nasal cavity; the cells are arranged in three groups, anterior, middle, and posterior, and are closed laterally by the orbital plate which forms part of the wall of the orbit. SYN: labyrinthus ethmoidalis [TA], ectethmoid, ectoethmoid, lateral mass of ethmoid bone.
- membranous l. [TA] a complex arrangement of communicating membranous canaliculi and sacs, filled with endolymph and surrounded by perilymph, suspended within the cavity of the bony l.; its chief divisions are the cochlear duct and the vestibular l.. SYN: labyrinthus membranaceus [TA].
- osseous l. SYN: bony l..
- vestibular l. [TA] the portion of the membranous l. concerned with the sense of equilibration (vs. the cochlear l., which is concerned with the sense of hearing) and innervated by the vestibular nerve; it is located within the semicircular canals and vestibule of the bony l., and consists of the utricle, saccule, and the semicircular, utriculosaccular, and endolymphatic ducts. SYN: labyrinthus vestibularis [TA], vestibular organ.
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lab·y·rinth 'lab-ə-.rin(t)th, -rən(t)th n a tortuous anatomical structure esp the inner ear or its bony or membranous part see BONY LABYRINTH, MEMBRANOUS LABYRINTH
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n.
a convoluted system of cavities and ducts comprising the organs of hearing and balance. The membranous labyrinth is a series of interconnected membranous canals and chambers consisting of the semicircular canals, utricle, and saccule (concerned with balance) and the central cavity of the cochlea (concerned with hearing). It is filled with a fluid, endolymph. The bony labyrinth is the system of the bony canals and chambers that surround the membranous labyrinth. It is embedded in the petrous part of the temporal bone and is filled with fluid (perilymph).
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lab·y·rinth (labґə-rinth) [Gr. labyrinthos] 1. labyrinthus (def. 1). 2. auris interna.Medical dictionary. 2011.