#Auditory canal function skin#

The skin of the pinna, canal, and drum are subject to all the disorders of the skin elsewhere in the body, and the presence of cerumen glands may lead to special problems. Patients often cough during examination of the ear because branches of the tenth nerve (Arnold's nerve) are stimulated. The canal is innervated by fibers from cranial nerves V, VII, IX, and X and thus is an exquisitely sensitive area. Proper painless cleansing of the ear canal is often necessary for adequate inspection. Any obstruction to the flow of energy through this system will create a hearing impairment. The external ear system collects sound energy for transmission into the ossicular chain (malleus, incus, and stapes) and thence to the fluids in the inner ear (cochlea). Ask the patient, 'Do you hear this better in the right or left ear?' If the patient hesitates, then the Weber test shows that sound is not being referred. Always remove a patient's wig if using the vertex. Remove false teeth and use the upper gum. Probably the most exact referral is from the incisor teeth. The thickness of the scalp or hair will sometimes prevent an accurate referral response. In the Weber test ( Figure 126.3) the fork is held firmly on the vertex of the skull in the midline, or firmly on the forehead, chin, or upper incisors.

The tragus should be pushed on to determine tenderness.įor the tuning-fork tests, the examiner, using a rubber reflex hammer or his or her elbow, strikes one tine strongly enough to produce a sound clearly perceived by the examiner at 30 cm. The pinna should be pulled firmly in all directions to determine tenderness. Prominent, protruding ears, called lop ears, are commonly seen. The external ear must be inspected carefully for nodules, growths, serious injuries, surgical scars, cysts, crusting, or fistulas. The combination of these two tests permits the examiner to use fundamental physiologic information in categorizing the patient's hearing as being within normal limits.Įxamination of the ear canal and eardrum of an adult. Bone conduction testing measures the integrity of the sensorineural structures (cochlea, eighth nerve, brainstem nuclei, and relays to the auditory cortex). This result is written BC > AC (i.e., bone conduction is better than air conduction).Īir conduction testing measures the integrity of the entire hearing apparatus from external ear to auditory cortex. If the patient has abnormal hearing, a tuning fork activated and held 2.5 cm from the ear and then placed on the mastoid process will be heard better behind the ear. The proper notation is AC > BC this indicates that air conduction is better than bone conduction. In the Rinne test, when an activated tuning fork is held 2.5 cm from the ear and then placed on the mastoid process, a normal subject will hear it better (louder or more distinctly) in front of the ear than behind the ear. If some sensorineural dysfunction exists in both ears, caused by aging deafness (presbycusis), ototoxicity from drugs, acoustic trauma from excess noise exposure, or following a central nervous system infection, a vibrating fork will be perceived in the ear with the best sensorineural function. (It is perceived by the patient as being in the middle of the head or on top of the head.) In an abnormal patient, the vibrating fork will be perceived in the ear with conductive hearing loss (drum perforation, impacted wax, middle ear fluid, stapes fixation, or otosclerosis), provided the other ear is normal. A normal response is no lateralization of the sound energy generated from the fork to either ear. With the Weber test, a tuning fork (usually 256 Hz) is activated and applied to the skull, the forehead, the chin, or the upper incisor teeth. The Rinne and Weber tuning-fork tests can be used in the office to evaluate hearing.

Abnormalities involving the skin, cartilage, bone, and eardrum may interfere with hearing. The ears-pinna, external auditory canal, and eardrum- are the sound-collection system for the body.

Auditory canal function