1/26/2024 0 Comments Pupil size chart for nursesTreating early acute otitis media with antibiotics is controversial in the United States due to the effort to prevent antibiotic resistance. If not treated, acute otitis media can potentially cause perforation of the tympanic membrane. Acute otitis media is diagnosed by a health care provider using an otoscope to examine the tympanic membrane for bulging and purulent fluid. This fluid can become infected, causing purulent fluid and low-grade fever. Acute otitis media typically occurs after an upper respiratory infection when the Eustachian tube becomes inflamed and the middle ear fills with fluid, causing ear pain and irritability. Children between the ages of 6 months and 2 years are more susceptible to ear infections because of the size and shape of their Eustachian tubes. Ear infections are a common illness in the pediatric population. Īcute otitis media is the medical diagnosis for an middle ear infection. However, they travel together from the inner ear to the brain stem as the vestibulocochlear nerve (cranial nerve VIII). The neural signals from these two regions are relayed to the brain stem through separate fiber bundles. The semicircular canals have two separate regions, the cochlea and the vestibule, that are responsible for hearing and balance. The inner ear is often described as a bony labyrinth because it is composed of a series of semicircular canals. The Eustachian tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning. The middle ear is also connected to the pharynx through the Eustachian tube that helps equilibrate air pressure across the tympanic membrane. The stapes is attached to the inner ear, where the sound waves are transduced into a neural signal. The incus, in turn, articulates with the stapes. The middle ear consists of a space with three small bones called the malleus, incus, and stapes, the Latin names that roughly translate to “hammer,” “anvil,” and “stirrup.” The malleus is attached to the tympanic membrane and articulates with the incus. The auricle, ear canal, and tympanic membrane are referred to as the external ear. At the end of the ear canal is the tympanic membrane, commonly referred to as the eardrum, that vibrates after it is struck by sound waves. The C-shaped curves of the auricle direct sound waves toward the ear canal. The large, fleshy structure on the lateral aspect of the head is known as the auricle. See Figure 8.15 for an image of the anatomy of the ear. Hearing is the transduction of sound waves into a neural signal by the structures of the ear. These nerve cells of the retina leave the eye and enter the brain via the optic nerve (cranial nerve II). The cones are sensitive to different wavelengths of light and provide color vision. Two types of photoreceptors within the retina are the rods and the cones. The innermost layer of the eye is the retina that contains the nervous tissue and specialized cells called photoreceptors for the initial processing of visual stimuli. The cornea can be reshaped by surgical procedures such as LASIK. The cornea, with the anterior chamber and lens, refracts light and contributes to vision. The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. The iris constricts the pupil in response to bright light and dilates the pupil in response to dim light. The iris is a smooth muscle that opens and closes the pupil, the hole at the center of the eye that allows light to enter. The conjunctiva extends over the white areas of the eye called the sclera, connecting the eyelids to the eyeball. The inner surface of each lid is a thin membrane known as the conjunctiva. The eyelids, with lashes at their leading edges, help to protect the eye from abrasions by blocking particles that may land on the surface of the eye. See Figure 8.1 for an illustration of the eye. The eyes are located within either orbit in the skull. Our sense of vision occurs due to transduction of light stimuli received through the eyes.
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