the cochlea semicircular canals and vestibular sacs make up the
Inner ear
its precise incidence cannot be determined. Birds have an auditory system similar to that of mammals, including a cochlea. Reptiles, amphibians, and fish do not have cochleas but hear with simpler auditory organs or vestibular organs, which generally detect lower-frequency sounds than the cochlea. In reptiles, sound is transmitted to the inner ear by the stapes (stirrup) bone of the middle ear. This is pressed against the oval window, a membrane-covered opening on the surface of the vestibule. From here, sound waves are conducted through a short perilymphatic duct to a second opening, the round window, which equalizes pressure, allowing
Inner ear
Crista ampullaris The crista ampullaris is the sensory organ of rotation. They are found in the ampullae of each of the semicircular canals of the inner ear, meaning that there are 3 pairs in total. The function of the crista ampullaris is to sense angular acceleration and deceleration. The inner ear comprises three specialized regions of the membranous labyrinth: the vestibular sacs – the utricle and saccule, and the semicircular canals, which are the vestibular organs, as well as the cochlear duct, which is involved in the special sense of hearing. The semicircular canals are filled with endolymph due to
Crista ampullaris
Vestibular evoked myogenic potential The vestibular evoked myogenic potential (VEMP or VsEP) is a neurophysiological assessment technique used to determine the function of the otolithic organs (utricle and saccule) of the inner ear. It complements the information provided by caloric testing and other forms of inner ear (vestibular apparatus) testing. The vestibular system helps a person maintain: balance, visual fixation, posture, and lower muscular control. There are six receptor organs located in the inner ear: cochlea, utricle, saccule, and the lateral, anterior, and posterior semicircular canals. The cochlea is a sensory organ with the primary purpose to aid in hearing.
Vestibular evoked myogenic potential
the brain. The vestibular system is the region of the inner ear where the semicircular canals converge, close to the cochlea. The vestibular system works with the visual system to keep objects in view when the head is moved. Joint and muscle receptors are also important in maintaining balance. The brain receives, interprets, and processes the information from all these systems to create the sensation of balance. The vestibular system of the inner ear is responsible for the sensations of balance and motion. It uses the same kinds of fluids and detection cells (hair cells) as the cochlea uses, and
Inner ear
ampullaris. The hair cells respond by stimulating neurons that innervate them. Crista ampullaris The crista ampullaris is the sensory organ of rotation. They are found in the ampullae of each of the semicircular canals of the inner ear, meaning that there are 3 pairs in total. The function of the crista ampullaris is to sense angular acceleration and deceleration. The inner ear comprises three specialized regions of the membranous labyrinth: the vestibular sacs – the utricle and saccule, and the semicircular canals, which are the vestibular organs, as well as the cochlear duct, which is involved in the special sense
Crista ampullaris
cognitive and emotional disorders, including depersonalization and derealization. Vestibular system The vestibular system, in most mammals, is the sensory system that provides the leading contribution to the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals. As movements consist of rotations and translations, the vestibular system comprises two components: the semicircular canals which indicate rotational movements; and the otoliths which indicate linear accelerations. The vestibular system sends signals primarily to the neural structures that
Vestibular system
Vestibular system The vestibular system, in most mammals, is the sensory system that provides the leading contribution to the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals. As movements consist of rotations and translations, the vestibular system comprises two components: the semicircular canals which indicate rotational movements; and the otoliths which indicate linear accelerations. The vestibular system sends signals primarily to the neural structures that control eye movements, and to the muscles that
Vestibular system
cochlear nuclei. Cochlear nerve The cochlear nerve (also auditory or acoustic neuron) 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. In terms of anatomy, an auditory nerve fiber is either bipolar or unipolar, with its distal projection being called the
Cochlear nerve
Cochlear nerve The cochlear nerve (also auditory or acoustic neuron) 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. In terms of anatomy, an auditory nerve fiber is either bipolar or unipolar, with its distal projection being called the peripheral process,
Cochlear nerve
rotating gaze direction in the opposite direction, by an amount that depends on distance. The VOR is ultimately driven by signals from the vestibular apparatus in the inner ear. The semicircular canals detect head rotation and drive the rotational VOR, whereas the otoliths detect head translation and drive the translational VOR. The main "direct path" neural circuit for the horizontal rotational VOR is fairly simple. It starts in the vestibular system, where semicircular canals get activated by head rotation and send their impulses via the vestibular nerve (cranial nerve VIII) through the vestibular ganglion and end in the vestibular nuclei
Vestibulo–ocular reflex
via the pharyngeal opening of the Eustachian tube. The inner ear contains the otolith organs—the utricle and saccule—and the semicircular canals belonging to the vestibular system, as well as the cochlea of the auditory system. The outer ear is the external portion of the ear and includes the fleshy visible pinna (also called the auricle), the ear canal, and the outer layer of the eardrum (also called the tympanic membrane). The pinna consists of the curving outer rim called the helix, the inner curved rim called the antihelix, and opens into the ear canal. The tragus protrudes and partially obscures
Ear
stapes pushes the secondary tympanic membrane, fluid in the inner ear moves and pushes the membrane of the round window out by a corresponding amount into the middle ear. The ossicles help amplify sound waves by nearly 15–20 times. The inner ear sits within the temporal bone in a complex cavity called the bony labyrinth. A central area known as the vestibule contains two small fluid-filled recesses, the utricle and saccule. These connect to the semicircular canals and the cochlea. There are three semicircular canals angled at right angles to each other which are responsible for dynamic balance. The cochlea
Ear
of a flight instructor. Instrument-rated pilots also use view-limiting devices supervised by an instructor or a safety pilot to practise instrument flight and maintain instrument flying proficiency. The inner ear contains the vestibular system, which is also known as the organ of equilibrium. About the size of a pencil eraser, the vestibular system contains two distinct structures: the semicircular canals, which detect changes in angular acceleration, and the otolith organs (the utricle and the saccule), which detect changes in linear acceleration and gravity. Both the semicircular canals and the otolith organs provide information to the brain regarding the body’s position
Graveyard spiral
a rate below human motion threshold so that the subject does not detect the so-called "wash out" phase of simulator motion cueing. The motion system is then ready to make the next acceleration which will be detected by the subject, as in the real world. This so-called "acceleration onset cueing" is an important aspect in simulators with motion platforms and models the way humans feel motions in the real world. The vestibular system is the balance and equilibrium system of the body that includes the left and right vestibular organs of the "inner ear". It consists of three semicircular canals,
Motion simulator
organ of Corti that are responsible for activation of afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound. The exact mechanism by which sound is transmitted by the neurons of the cochlear nerve is uncertain; the two competing theories are place theory and temporal theory. The vestibular nerve travels from the vestibular system of the inner ear. The vestibular ganglion houses the cell bodies of the bipolar neurons and extends processes to five sensory organs. Three of these are the cristae located in the ampullae of the semicircular canals. Hair cells of the
Vestibulocochlear nerve
moving. The third type is known as pseudovertigo, an intensive sensation of rotation inside the person's head. While this classification appears in textbooks, it has little to do with the pathophysiology or treatment of vertigo. Vertigo that is caused by problems with the inner ear or vestibular system, which is composed of the semicircular canals, the vestibule (utricle and saccule), and the vestibular nerve is called "peripheral", "otologic" or "vestibular" vertigo. The most common cause is benign paroxysmal positional vertigo (BPPV), which accounts for 32% of all peripheral vertigo. Other causes include Ménière's disease (12%), superior canal dehiscence syndrome, labyrinthitis,
Vertigo
have tympani that are larger than their eyes while in females, the eyes and tympani are much the same size. A noise causes the tympanum to vibrate and the sound is transmitted to the middle and inner ear. The middle ear contains semicircular canals which help control balance and orientation. In the inner ear, the auditory hair cells are arranged in two areas of the cochlea, the basilar papilla and the amphibian papilla. The former detects high frequencies and the latter low frequencies. Because the cochlea is short, frogs use electrical tuning to extend their range of audible frequencies and
Frog
and somatosensory inputs to make postural adjustments when the body becomes displaced from its normal vertical position. These inputs are used to create what is called an efference copy. This means that the brain makes comparisons in the cerebellum between expected posture and perceived posture, and corrects for the difference. The reflex takes 6 or 7 weeks to perfect, but can be affected by various types of balance disorders. The righting reflex has also been studied in cats and other non-human mammals. The vestibular system is composed of inner ear organs forming the "labyrinth": the semicircular canals, the otoliths, and
Righting reflex
is transport of fluid and electrolytes. Reissner's membrane is named after German anatomist Ernst Reissner (1824-1878). Vestibular membrane The vestibular membrane, vestibular wall or Reissner's membrane (), is a membrane inside the cochlea of the inner ear. It separates the cochlear duct from the vestibular duct. Together with the basilar membrane it creates a compartment in the cochlea filled with endolymph, which is important for the function of the spiral organ of Corti. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth. Histologically, the membrane is composed of
Vestibular membrane
Vestibular membrane The vestibular membrane, vestibular wall or Reissner's membrane (), is a membrane inside the cochlea of the inner ear. It separates the cochlear duct from the vestibular duct. Together with the basilar membrane it creates a compartment in the cochlea filled with endolymph, which is important for the function of the spiral organ of Corti. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth. Histologically, the membrane is composed of two layers of flattened epithelium, separated by a basal lamina. Its structure suggests that its function
Vestibular membrane
called perilymph. The scala media contains endolymph. A set of membranes called the vestibular membrane and the basilar membrane develop to separate the cochlear duct from the vestibular duct and the tympanic duct, respectively. Parts of the otic vesicle in turn form the vestibulocochlear nerve. These form bipolar neurons which supply sensation to parts of the inner ear (namely the sensory parts of the semicircular canals, macular of the utricle and saccule, and organ of Corti). The nerve begins to form around the 28th day. Most of the genes responsible for the regulation of inner ear formation and its morphogenesis
Ear
part of the recessus ellipticus are perforated by a number of holes (macula cribosa superior). The apertures in the pyramid transmit the nerves to the utricle; those in the recessus ellipticus are the nerves to the ampullæ of the superior and lateral semicircular ducts. Behind, the five orifices of the semicircular canals can be found. In the frontal view, there is an elliptical opening which communicates with the scala vestibuli of the cochlea. 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 (tympanic cavity),
Vestibule of the ear
are still active, or silent, at the same time. The HD network makes use of inertial and other movement-related inputs, and thus continues to operate even in the absence of light. These inertial properties are dependent on the vestibular system, especially the semicircular canals of the inner ear, which signal rotations of the head. The HD system integrates the vestibular output to maintain a signal reflecting cumulative rotation. The integration is less than perfect, though, especially for slow head rotations. If an animal is placed on an isolated platform and slowly rotated in the dark, the alignment of the HD
Head direction cells
Sense of balance The sense of balance or equilibrioception is one of the physiological senses related to balance. It helps prevent humans and animals from falling over when standing or moving. Balance is the result of a number of body systems working together: the eyes (visual system), ears (vestibular system) and the body's sense of where it is in space (proprioception) ideally need to be intact. The vestibular system, the region of the inner ear where three semicircular canals converge, works with the visual system to keep objects in focus when the head is moving. This is called the vestibulo-ocular
Sense of balance
two are genetic factors and vascular damage to the labyrinth. Although BPPV can occur at any age, it is most often seen in people over the age of 60. Besides aging, there are no major risk factors known for BPPV, although previous episodes of head trauma, or the inner ear infection labyrinthitis, may predispose to the future development of BPPV. The inside of the ear is composed of an organ called the vestibular labyrinth. The vestibular labyrinth includes semicircular canals, which contain fluids and fine hairlike sensors which act as a monitor to the rotations of the head. An important
Benign paroxysmal positional vertigo
the turn. As the endolymph stabilizes, the semicircular canals stop registering the gradual turn and the aircraft slowly loses altitude until impact with the ground. Jean Pierre Flourens, by destroying the horizontal semicircular canal of pigeons, noted that they continue to fly in a circle, showing the purpose of the semicircular canals. Semicircular canals The semicircular canals or semicircular ducts are three semicircular, interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the horizontal, superior and posterior semicircular canals. The semicircular canals are a component of the bony labyrinth. At one end
Semicircular canals
Semicircular canals The semicircular canals or semicircular ducts are three semicircular, interconnected tubes located in the innermost part of each ear, the inner ear. The three canals are the horizontal, superior and posterior semicircular canals. The semicircular canals are a component of the bony labyrinth. At one end of each of the semicircular canals is a dilated sac called an osseous ampulla which is more than twice the diameter of the canal. Each ampulla contains an ampulla crest, the crista ampullaris which consists of a thick gelatinous cap called a cupula and many hair cells. The superior and posterior semicircular
Semicircular canals
Perilymph Perilymph is an extracellular fluid located within the inner ear. It is found within the semicircular canals and the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation in perilymph is sodium, with the values of sodium and potassium concentration in the perilymph being 138 mM and 6.9 mM, respectively. It is also named Cotunnius' liquid and liquor cotunnii for Domenico Cotugno. The inner ear has two parts: the bony labyrinth and the membranous labyrinth. The membranous labyrinth is contained within the bony
Perilymph
the "fissula ante fenestram". Bony labyrinth The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts: the vestibule, semicircular canals, and cochlea. These are cavities hollowed out of the substance of the bone, and lined by periosteum. They contain a clear fluid, the perilymph, in which the membranous labyrinth is situated. A fracture classification system in which temporal bone fractures detected on CT are delineated based on disruption of the otic capsule has been found to be predictive for complications of temporal
Bony labyrinth
Bony labyrinth The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts: the vestibule, semicircular canals, and cochlea. These are cavities hollowed out of the substance of the bone, and lined by periosteum. They contain a clear fluid, the perilymph, in which the membranous labyrinth is situated. A fracture classification system in which temporal bone fractures detected on CT are delineated based on disruption of the otic capsule has been found to be predictive for complications of temporal bone trauma such as
Bony labyrinth
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 (tympanic cavity), behind the cochlea, and in front of the three semicircular canals. The name comes from the Latin "vestibulum", literally an entrance hall. 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 (fenestra vestibuli), closed, in the fresh state, by the base of
Vestibule of the ear
the proprioceptive system (posture, position of the body) conflicts with misperceived information from the semicircular canals and the otoliths within the inner ear. This is known as the ‘neural mismatch theory’ and was first suggested in 1975 by Reason and Brand. Alternatively, the fluid shift hypothesis suggests that weightlessness reduces the hydrostatic pressure on the lower body causing fluids to shift toward the head from the rest of the body. These fluid shifts are thought to increase cerebrospinal fluid pressure (causing back aches), intracranial pressure (causing headaches), and inner ear fluid pressure (causing vestibular dysfunction). Despite a multitude of studies
Micro-g environment
because they cannot stabilize the eyes during small head tremors, and also because damage to the VOR can cause vestibular nystagmus. The VOR does not depend on visual input. It can be elicited by caloric (hot or cold) stimulation of the inner ear, and works even in total darkness or when the eyes are closed. However, in the presence of light, the fixation reflex is also added to the movement. In other animals, the gravity organs and eyes are strictly connected. A fish, for instance, moves its eyes by reflex when its tail is moved. Humans have semicircular canals, neck
Vestibulo–ocular reflex
2,000 mg/kg for oral maropitant in rats. Vomiting is caused when impulses from the chemoreceptor trigger zone (CRTZ) in the brain are sent to the vomiting center in the medulla. Motion sickness specifically occurs when signals to the CRTZ originate from the inner ear: motion is sensed by the fluid of the semicircular canals, which causes overstimulation. The signal travels to the brain's vestibular nuclei, then to the CRTZ, and finally to the vomiting center. Maropitant has a similar structure to substance P, the key neurotransmitter in causing vomiting, which allows it to act as an antagonist and bind to
Maropitant
sauropods for which inner ears have been studied. The first skeletal reconstructions show the skull in a near-horizontal posture. Salgado (1999) argued that such a posture would have been anatomically impossible due to the elongated neural spines of the neck vertebrae. Instead, he envisaged the head in a nearly vertical orientation. The habitual orientation of the head is usually reflected by the orientation of the semicircular canals of the inner ear, which housed the sense of balance (vestibular system). Using their three-dimensional model of the inner ear, Carabajal and colleagues suggested that the snout faced downwards at an angle of
Amargasaurus
otoliths and semicircular canals of the inner ear. It is unclear whether or not these stimuli are encountered in significant amounts in a simulator to induce sickness in the expert pilots. However, since laboratory studies have shown the removal of the vestibular projection areas of the cerebellum (in laboratory animals) to result in insusceptibility to motion sickness, it is almost certainly probable that the first of these theories holds the most promise with regard to research into the direct physiological causes of the phenomenon. While anyone can experience simulator sickness, studies in flight simulators have found a correlation between the
Simulator sickness
in simulators seems obvious: if the perception of real-world events can be modelled, they will provide the user a near-identical experience. However, in simulator motion this can only be achieved in the initial acceleration, which cannot be sustained because of the physical limits of the size of the motion platform. Fortunately, the motion sensors of the human body respond to accelerations rather that sustained motion, and so a well-programmed 6-jack ("Hexapod") motion platform is very effective in motion cueing. The human motion sensors consist of the Inner Ear (the Vestibular Apparatus) with three semicircular canals for sensing rotations (Pitch, roll,
Motion simulator
aqueducts often occur with other inner ear development problems, such as cochlear deformities. Enlarged vestibular aqueducts are part of the classic Mondini deformity. Enlarged vestibular aqueducts with enlarged endolymphatic sacs occur in Pendred syndrome which is caused by a defect on chromosome 7q31.. Enlarged vestibular aqueducts can also occur in Branchio-oto-renal syndrome, CHARGE syndrome and renal tubular acidosis. Enlarged vestibular aqueducts can be bilateral or unilateral. Hearing loss caused by large vestibular aqueduct syndrome is not inevitable, although people with the syndrome are at a much higher risk of developing hearing loss than the general population. Hearing loss is very
Enlarged vestibular aqueduct
Mondini dysplasia Mondini dysplasia, also known as Mondini malformation and Mondini defect, is an abnormality of the inner ear that is associated with sensorineural hearing loss. This deformity was first described in 1791 by Mondini after examining the inner ear of a deaf boy. The Mondini dysplasia describes a cochlea with incomplete partitioning and a reduced number of turns, an enlarged vestibular aqueduct and a dilated vestibule. A normal cochlea has two and a half turns, a cochlea with Mondini dysplasia has one and a half turns; the basal turns being normally formed with a dilated or cystic apical turn
Mondini dysplasia
Peoples Drug Peoples Drug was a chain of drugstores based in Alexandria, Virginia, a suburb of Washington, D.C. Founded in 1905, Peoples was subsequently purchased by Lane Drug in 1975, Imasco in 1984, and finally by CVS in 1990, which continued to run the stores under the Peoples banner until 1994, at which time the stores were converted to CVS, marking the end of the use of the Peoples Drug name. Peoples Drug was founded by Malcolm Gibbs in 1905 at 824 7th Street, NW. By 1930, it had 110 stores operating under the Peoples Drugs, Days Drug, and Shearer
Peoples Drug
La Cruz, Chile La Cruz () is a city and commune in the Quillota Province of central Chile's fifth region of Valparaíso. The Mediterranean climate of Chile's Zona Central allows for a rich quality and variety of flora and fauna. Because of this climate, La Cruz produces many fruits and vegetables, and is known as the "National Capital of the Avocado", The town is also one of the main producers of chirimoya, a fruit with a green shell and white meat. The commune of La Cruz spans an area of . According to the 2002 census of the National Statistics
La Cruz, Chile
Prevailing winds and weather types change follow the monsoon pattern. It is warm and moist when the southeast and southwest winds coming from Pacific Ocean, and typhoons are relatively common during summertime; and is dry and slightly cold when the north winds coming from Siberia or the northern part of Mainland China. During the transition period from northeast monsoon to southwest monsoon (March and April), the weather is moist and foggy. It is Macau's spring season. Summer is from May to September, when the southeast and southwest monsoon prevailing. It is rather hot and rainy. The weather in autumn (the
Geography of Macau
produced about £2,500. Nanswhyden House was destroyed by fire on 30 November 1803, with its collections of ancient documents, the records relating to the Stannary parliament, and a cabinet of minerals. Robert Hoblyn Robert Hoblyn MP FRS (1710–1756) was an English politician and book collector. Hoblyn was born at Nanswhyden House, and baptised at St. Columb Major in Cornwall 5 May 1710. His father, Francis Hoblyn, born in 1687, a J.P. for Cornwall and a member of the Stannary parliament, was buried at St Columb on 9 November 1711. His mother was Penelope, daughter of Colonel Sidney Godolphin of Shropshire.
Robert Hoblyn
sense that its implementation can be adapted to countries' specific situations and priorities. Coordination of the implementation of the SEEA and on-going work on new methodological developments is managed and supervised by the UN Committee of Experts on Environmental-Economic Accounting (UNCEEA). The final, official version of the SEEA Central Framework was published in February 2014. Whilst measuring the components of natural capital in any region is a relatively straightforward process, both the task and the rationale of putting a monetary valuation on them, or on the value of the goods and services they freely give us, has proved more contentious.
Natural capital
its connection with the cochlear duct via the saccule, which also contains endolymph. It also contains an inner membranous sleeve that lines the semicircular canals. The canals also contain the crista ampullaris. The receptor cells located in the semicircular ducts are innervated by the eighth cranial nerve, the vestibulocochlear nerve (specifically the vestibular portion). The crista ampullaris itself is a cone-shaped structure, covered in receptor cells called "hair cells". Covering the crista ampullaris is a gelatinous mass called the cupula. Upon angular acceleration (rotation), the endolymph within the semicircular duct deflects the cupula against the hair cells of the crista
Crista ampullaris
overview also explains acceleration as its processes are interconnected with balance. There are five sensory organs innervated by the vestibular nerve; three semicircular canals (Horizontal SCC, Superior SCC, Posterior SCC) and two otolith organs (Saccule and Utricle). Each semicircular canal (SSC) is a thin tube that doubles in thickness briefly at a point called osseous ampullae. At their center-base each contains an ampullary cupula. The cupula is a gelatin bulb connected to stereocilia, affected by the relative movement of the endolymph it is bathed in. Since the cupula is part of the bony labyrinth it rotates along with actual head
Sense of balance
Righting reflex The righting reflex, also known as the labyrinthine righting reflex, is a reflex that corrects the orientation of the body when it is taken out of its normal upright position. It is initiated by the vestibular system, which detects that the body is not erect and causes the head to move back into position as the rest of the body follows. The perception of head movement involves the body sensing linear acceleration or the force of gravity through the otoliths, and angular acceleration through the semicircular canals. The reflex uses a combination of visual system inputs, vestibular inputs,
Righting reflex
and the three semicircular canals. The vestibule is the name of the fluid-filled, membranous duct than contains these organs of balance. The vestibule is encased in the temporal bone of the skull. 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 vestibular duct of the cochlea. Its cavity does not directly communicate with that of the utricle. The anterior part of the saccule exhibits an oval thickening, the macula acustica sacculi, or macula, to which are distributed the saccular filaments of
Saccule
alcohol levels are highest. PAN II will eventually cause subjective vertigo in the opposite direction. This occurs several hours after ingestion and after a relative reduction in blood alcohol levels. Benign paroxysmal positional vertigo (BPPV) is a condition resulting in acute symptoms of vertigo. It is probably caused when pieces that have broken off otoliths have slipped into one of the semicircular canals. In most cases, it is the posterior canal that is affected. In certain head positions, these particles shift and create a fluid wave which displaces the cupula of the canal affected, which leads to dizziness, vertigo and
Vestibular system
Inner ear
Title: Inner ear. Content: its precise incidence cannot be determined. Birds have an auditory system similar to that of mammals, including a cochlea. Reptiles, amphibians, and fish do not have cochleas but hear with simpler auditory organs or vestibular organs, which generally detect lower-frequency sounds than the cochlea. In reptiles, sound is transmitted to the inner ear by the stapes (stirrup) bone of the middle ear. This is pressed against the oval window, a membrane-covered opening on the surface of the vestibule. From here, sound waves are conducted through a short perilymphatic duct to a second opening, the round window, which equalizes pressure, allowing
Vestibular apparatus
Inner ear
vestibular system
inner ear
vestibular system
inner ear