This involves specialized cells called hair cells that occur in the inner ear and feed auditory messages to the auditory nerve, the eighth cranial nerve. Cranial nerves are those nerves that arise within the brain and there are a total of twelve of these nerves. The causes of a sensorineural hearing loss are usually more serious and include tumors and other diseases including those involving decreased blood flow. The hearing is tested by both air and bone conduction. Air conduction tests how well the person hears using the ear canal, the middle and inner ears as well as the eighth nerve.
Bone conduction is tested by placing a vibrating tuning fork against the head.
This method directly tests the inner ear and the eighth nerve and is a shortcut past the external and middle ear areas. Hearing tests involve the use of an audiometer, an instrument that can measure the decibel level and frequency of the hearing loss. The nose is the next area of concern as we proceed on our exam. On examination one looks at the tissue of the nostrils for evidence of swelling or draining of secretions. The septum, the bony ridge between the nostrils is also lined with tissue and is quite sensitive.