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Macula Of Saccule
The saccule is the smaller sized vestibular sac (the utricle being the other larger size vestibular sac); it is globular in form, and lies in the recessus sphæricus near the opening of the scala vestibuli of the cochlea. Its anterior part exhibits an oval thickening, the macula of saccule (or saccular macula), to which are distributed the saccular filaments of the acoustic nerve. The vestibule is a region of the inner ear which contains the saccule and the utricle, each of which contain a macula to detect linear acceleration. Its function is to detect vertical linear acceleration. The macula of saccule lies in a nearly vertical position. It is a 2mm by 3mm patch of hair cells. Each hair cell of the macula contains 40 to 70 stereocilia and one true cilia, called a kinocilium. A gelatinous cover called the otolithic membrane envelops the tips of the stereocilia and kinocilium. The otolithic membrane is weighted with small densely packed protein- calcium carbonate granules call ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccule
The saccule is a bed of sensory cells in the inner ear. It translates head movements into neural impulses for the brain to interpret. The saccule detects linear accelerations and head tilts in the vertical plane. When the head moves vertically, the sensory cells of the saccule are disturbed and the neurons connected to them begin transmitting impulses to the brain. These impulses travel along the vestibular portion of the eighth cranial nerve to the vestibular nuclei in the brainstem. The vestibular system is important in maintaining balance, or equilibrium. The vestibular system includes the saccule, utricle, and the three semicircular canals. The vestibule is the name of the fluid-filled, membranous duct that contains these organs of balance. The vestibule is encased in the temporal bone of the skull. Structure The saccule, or sacculus, is the smaller of the two vestibular sacs. It is globular in form and lies in the recessus sphæricus near the opening of the vest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vestibule Of The Ear
The vestibule is the central part of the bony labyrinth in the inner ear, and is situated medial to the eardrum, behind the cochlea, and in front of the three semicircular canals. The name comes from the Latin ', literally an entrance hall. Structure The vestibule is somewhat oval in shape, but flattened transversely; it measures about 5 mm from front to back, the same from top to bottom, and about 3 mm across. In its lateral or tympanic wall is the oval window, closed, in the fresh state, by the base of the stapes and annular ligament. On its medial wall, at the forepart, is a small circular depression, the recessus sphæricus, which is perforated, at its anterior and inferior part, by several minute holes (macula cribrosa media) for the passage of filaments of the acoustic nerve to the saccule; and behind this depression is an oblique ridge, the crista vestibuli, the anterior end of which is named the pyramid of the vestibule. This ridge bifurcates below to enclose ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Utricle (ear)
The utricle and saccule are the two otolith organs in the vertebrate inner ear. They are part of the balancing system (membranous labyrinth) in the vestibule of the bony labyrinth (small oval chamber). They use small stones and a viscous fluid to stimulate hair cells to detect motion and orientation. The utricle detects linear accelerations and head-tilts in the horizontal plane. The word utricle comes . Structure The utricle is larger than the saccule and is of an oblong form, compressed transversely, and occupies the upper and back part of the vestibule, lying in contact with the recessus ellipticus and the part below it. Macula The macula of utricle (macula acustica utriculi) is a small (2 by 3 mm) thickening lying horizontally on the floor of the utricle where the epithelium contains vestibular hair cells that allow a person to perceive changes in latitudinal acceleration as well as the effects of gravity; it receives the utricular filaments of the acoustic nerve. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scala Vestibuli
The vestibular duct or scala vestibuli is a perilymph-filled cavity inside the cochlea of the inner ear that conducts sound vibrations to the cochlear duct. It is separated from the cochlear duct by Reissner's membrane and extends from the vestibule of the ear to the helicotrema where it joins the tympanic duct. Additional images Image:Gray923.png, The cochlea and vestibule, viewed from above. Image:Gray903.png, Transverse section of the cochlear duct of a fetal cat. Image:Gray921.png, Interior of right osseous labyrinth. Image:Gray928.png, Diagrammatic longitudinal section of the cochlea. See also *Tympanic duct References internal websites Slidefrom University of Kansas Diagramat Indiana University – Purdue University Indianapolis Imageat University of New England (United States) The University of New England (UNE) is a private research university in Maine with campuses in Portland and Biddeford, as well as a study abroad campus in Tangier, Morocco. During t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cochlea
The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the Organ of Corti, the sensory organ of hearing, which is distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea. The name cochlea derives . Structure The cochlea (plural is cochleae) is a spiraled, hollow, conical chamber of bone, in which waves propagate from the base (near the middle ear and the oval window) to the apex (the top or center of the spiral). The spiral canal of the cochlea is a section of the bony labyrinth of the inner ear that is approximately 30 mm long and makes 2 turns about the modiolus. The cochlear structures include: * Three ''scalae'' or chambers: ** the vestibular duct or ''scala vestibuli'' (containing perilymph), which lies superior to the cochlear duct and abuts the oval window ** the ty ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustic Nerve
The cochlear nerve (also auditory nerve or acoustic nerve) is one of two parts of the vestibulocochlear nerve, a cranial nerve present in amniotes, the other part being the vestibular nerve. The cochlear nerve carries auditory sensory information from the cochlea of the inner ear directly to the brain. The other portion of the vestibulocochlear nerve is the vestibular nerve, which carries spatial orientation information to the brain from the semicircular canals, also known as semicircular ducts. Anatomy and connections In terms of anatomy, an auditory nerve fiber is either bipolar or unipolar, with its distal projection being called the peripheral process, and its proximal projection being called the axon; these two projections are also known as the "peripheral axon" and the "central axon", respectively. The peripheral process is sometimes referred to as a dendrite, although that term is somewhat inaccurate. Unlike the typical dendrite, the peripheral process generates and con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Acceleration
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the ''net'' force acting on that object. The magnitude of an object's acceleration, as described by Newton's Second Law, is the combined effect of two causes: * the net balance of all external forces acting onto that object — magnitude is directly proportional to this net resulting force; * that object's mass, depending on the materials out of which it is made — magnitude is inversely proportional to the object's mass. The SI unit for acceleration is metre per second squared (, \mathrm). For example, when a vehicle starts from a standstill (zero velocity, in an inertial frame of reference) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the vehicle turns, an accel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereocilia
Stereocilia (or stereovilli or villi) are non-motile apical cell modifications. They are distinct from cilia and microvilli, but are closely related to microvilli. They form single "finger-like" projections that may be branched, with normal cell membrane characteristics. They contain actin. Stereocilia are found in the vas deferens, the epididymis, and the sensory cells of the inner ear. Structure Stereocilia are cylindrical and non-motile. They are much longer and thicker than microvilli, form single "finger-like" projections that may be branched, and have more of the characteristics of the cellular membrane proper. Like microvilli, they contain actin and lack an axoneme. This distinguishes them from cilia. They do not have a Basal body at their base since they do not contain microtubules. They may or may not be covered by a glycocalyx coating. They have no fixed arrangement, different to the structure present in kinocilium. Function Stereocilia are found in: *the vas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cilium
The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projection that extends from the surface of the much larger cell body. Eukaryotic flagella found on sperm cells and many protozoans have a similar structure to motile cilia that enables swimming through liquids; they are longer than cilia and have a different undulating motion. There are two major classes of cilia: ''motile'' and ''non-motile'' cilia, each with a subtype, giving four types in all. A cell will typically have one primary cilium or many motile cilia. The structure of the cilium core called the axoneme determines the cilium class. Most motile cilia have a central pair of single microtubules surrounded by nine pairs of double microtubules called a 9+2 axoneme. Most non-motile cilia have a 9+0 axoneme that lacks the central pair o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinocilium
A kinocilium is a special type of cilium on the apex of hair cells located in the sensory epithelium of the vertebrate inner ear. Anatomy in humans Kinocilia are found on the apical surface of hair cells and are involved in both the morphogenesis of the hair bundle and mechanotransduction. Vibrations (either by movement or sound waves) cause displacement of the hair bundle, resulting in depolarization or hyperpolarization of the hair cell. The depolarization of the hair cells in both instances causes signal transduction via neurotransmitter release. Role in hair bundle morphogenesis Each hair cell has a single, microtubular kinocilium. Before morphogenesis of the hair bundle, the kinocilium is found in the center of the apical surface of the hair cell surrounded by 20-300 microvilli. During hair bundle morphogenesis, the kinocilium moves to the cell periphery dictating hair bundle orientation. As the kinocilium does not move, microvilli surrounding it begin to elongate and form ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
