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44 Cards in this Set
- Front
- Back
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The spherical recess is located where in the vestibule?
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The spherical recess is located on the medial wall.
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What are the macula cribrosa media and where are they located?
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The macula cribosa media are small perforations on the anterior and inferior part of the recessus sphaericus for the passage of filaments of the acoustic nerve to the saccule
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What are the two layers of the periosteum?
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The two layers of the periosteum include the fibrous CT layer and the perilymphatic epithelum, according to the COMD 3400 lecture notes. The innermost epithelial cells secrete perilymph which is a serous fluid similar to CSP.
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Where is the fossa cochlearis and what's it's purpose?
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Fossa cochlearis is a small depression, or recess, at the posterior end of the crista vestibuli where it bifurcates. The fossa cochlearis is perforated with minute holes (macula cribrosa media) for the passage of filaments of the acoustic nerve which supply the vestibular end of the cochlear duct.
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What is the fenestra vestibuli and where is it located?
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The fenestra vestibuli is commonly known as the oval window located on the lateral wall of the vestibule and closed by the base of the staples and the annular ligament.
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What is the aquaeductus vestibuli and where is it located?
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The aquaeductus vestibuli is an opening that transmits a small vein and becomes the ductus endolymphaticus which ends in the endolymphatic sac within the dura mater of the cranial cavity. It is located on the media wall, at the "hinder" part or back in the media portion of the elliptical recess
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Where are macula cribrosa superior?
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The perforations in the recessus ellipticus that transmit the acoustic nerves to the utricle and ampullae of the superior and lateral semicircular ducts.
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What is the cochlear aqueduct and where is it located?
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The cochlear aqueduct connects the scala tympani to the subarachnoid space. It is located in the base end on the medial wall (it looks like) of the scala tympani.
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Where is the ampulae of the superior semicircular canal located?
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The osseous ampullae of the superior semicircular canal is located on the anterior posterior part of the vestibule; the membranous ampullae is connected to the anterior posterior part of the utricle.
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Where is the ampulae of the lateral semicircular canal located?
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The ampullae of the lateral semicircular canal is located on the posterior part of the osseous vestibule just below the ampullae of the superior semicircular canal. The membranous ampullae opens into the utricule.
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Where is the terminus of the scala vestibuli?
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The scala vestibule butts up against the recessus cochlea which appears to be a small depression within the pyramid of the vestibule that is anterior to the crista vestibuli
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Where is the endolymphatic sac located?
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The endolymphatic sac is located in the dura within the cranial cavity.
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The modiolus arises from where?
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The modiolus arises from the fundus of the internal auditory canal and carries within it the fibers of the cochlear nerve.
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What is the name of the canal that carries the facial and acoustic nerves from the brain?
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The internal acoustic meatus is a short canal, about 1 cm, in length, which runs lateralward and transmits the facial and acoustic nerves.
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What is the crista falciformis?
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The crista falciformis the crest dividing the lateral end of the acoustic canal into two unequal parts that are perforated, as far as I can tell, to allow the acoustic nerve to be transmitted to the area cribraosa media in the saccule, and the foramen singulare.
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What is the foramen singulare?
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The foramen singulare is the opening for the nerve to the posterior semicircular duct.
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What is the tractus spiralis foraminosus?
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The tractus spiralis foraminosus is a number of small spirally arranged openings which encircle the canalis centralis cochlear which transmits nerves to the cochlea.
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What is the area cribrosa superior?
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The area cribrosa superior are the small openings into the urticle, superior and lateral semicircular ducts for passage of the fibers of the acoustic nerve.
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What is the area facians?
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The area facians is in font of the area cribrosa superior that houses the one large opening, or commencement of the canal, for the facial nerve, called the aquaeductus Fallopii.
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What is the aqueduct of the vestibule?
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The aqueduct of the vestibule is a small slit behind the acoustic meatus for transmitting the duductus endolymphaticus.
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Describe the superior semicircular canal .
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The SSC is 15 -20mm long, lies transversely to the long axis of the petrous portion. Its lateral extremity is ampullated and opens into the upper vestibule. The opposite end joins the upper part of the posterior canal in the crus commune which opens into the upper-medially part of the vestibule.
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Describe the posterior canal.
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Like the superior canal, it is vertical in direction, but directed backward, nearly parallel to the posterior surface of the petrous bone. It's the longest of the 3 at 18-22mm,; its lower end is ampullated and opens into the lower-back part of the vestibule below the oval window.
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Describe the lateral semicircular canal.
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It's the shortest at 12-15mm in length. It's arch is directed horizontally backward and lateralward. Its amullated end corresponds to the upper and lateral angle of the vestibule, just above the fenestra vestibuli (oval window). The lateral canal in one ear is in the same plane as the canal in the other ear, while the superior canal of one ear is parallel to the posterior canal of the other ear.
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Length of the cochlear duct.
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6 - 12 mm long
diameter is 138um |
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Length of scala tympani, scala vestibule.
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28.28 and 31.5, respectively
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What is the total volume of the inner ear?
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208.26 ul
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Name the three planes of dynamic position of each of the semicircular canals.
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Transverse plane: lateral
Sagittal plane: superior Fontal plane: posterior |
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Explain how movement is communicated within the semicircular canals.
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When our heads move, the endolymph moves within the plane of the semicircular canal pushing on the cupula, bending it and deflecting the hairs that stimulate the receptors.
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What is the relationship between the left and right semicircular canals?
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The left and right semicircular canals are mirror images of each other so when the head is turned left, for example, the fluid in both ear's canals start moving right, but only one of the canals gets depolarized by the leftward movement and only one is depolarized by rightward.
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Explain the mirror relationship between the semicircular canals in both ears.
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When you turn your head left, the hair cells in one horizontal semicircular canal are thrown into an excitatory state while those in the other are inhibited.
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What wall in the cochlear duct is formed by the stria vascularis?
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The lateral wall of the cochlear duct is formed by the stria vascularis.
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Describe Reissner's membrane.
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Reissner's membrane is the third side of the cochlear duct and separates perilymphatic space (scala vestibuli) from endolymphatic space (cochlear duct). It is two layers thick being composed of simple squamous epithelium (toward endolymph) and a connective membrane.
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Describe the job of the stria vascularis and its cells.
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Histologically, the stria is a very highly specialized stratified epithelium, with capillaries that invade the territory of the epithelium. The lower cells of the epithelium are richly supplied with mitochondria and basal infoldings which are characteristics of cells involved in the control of water and electrolytes. The stria plays an important role in cochlear function by producing endolymph, whose ionic composition more closely resembles intracellular fluid than it does CSF. In the process of producing endolymph (the fluid of the scala media), the stria is also responsible for maintenance of the +90 mv endocochlear potential within the cochlear duct. Endolymph is resorbed through the wall of the endolymphatic sac into the vessels of the dura matter.
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Describe the head movement that will cause the endolymph in the posterior, superior, and lateral semicircular canals.
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Movement of the head up and down causes the endolymph in the posterior semicircular canal to move; side to side in the superior canal; and back and forth on a horizontal plane will cause movement of the endolymph in the lateral semicircular canal.
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What is the limbus?
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A thickened periosteum coming off the scala vestibular lip, confined to the attachment of the basilar membrane. It is opposite the spiral ligament.
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Where is the basilar membrane?
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The membrane that extends from the margin of the bony shelf of the cochlea to its outer wall and on which the sensory cells of the organ of Corti rest.
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What are the border cells of Held?
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Flat, large, irregular, multifaceted polygonal epithelial cell supporting inner hair cells, and covering the vestibular lip.
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What are the inner phalangeal cells?
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The inner phalangeal cells are arranged in two rows between border cells and inner pillars; inner hair cells are surrounded by the inner phalangeal cells,
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What is the reticular lamina.
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The sensory cells of the organ of Corti are held in place by specialized supporting cells.The hair cells are tightly gripped at their apical ends by processes of one of the filamentous; supporting cells, the phalangeal cells. These phalangeal processes together form the reticular lamina.
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What forms the lateral wall of the cochlear duct?
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The lateral wall of the cochlear duct is formed by the stria vascularis.
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Purpose of the phalangeal cells.
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The phalangeal cells are supporting cells for hair cells; they provide mechanical support and enable nerve endings to contact their basal parts.
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What structure rests on top of the reticular lamina?
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The reticular lamina is covered by the tectorial membrane.
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Where is the limbus spiralis?
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The osseous spiral lamina consists of two plates of bone. On the upper plate, which is the outside of the scala vestibuli, it is thickened to form the limbus spirialis and ends externally concavity called the inner sulcus.
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