This leads to an increased range of motion of the stapes to sound, causing hyperacusis. In conditions where the facial nerve is compromised, the stapedius muscle will be nonfunctional. The stapedius muscle that attaches to the stapes is responsible for dampening sounds. Treatment for these patients commonly involves surgery to remove the growth. The location of the choleastoma plays a large role in which the ossicle may be damaged. Choleastomas that grow rapidly can damage the ossicles and lead to significant hearing loss.

The abnormal growths can be either acquired or congenital. Ĭholeastomas are benign growths of keratinized squamous epithelium that are commonly located within the middle ear. Surgically, patients can be treated with stapedotomy for patients who are refractory to medical management. Medically, patients can be treated with bisphosphonates to prevent excessive bony growth. Treatment can involve medical or surgical management. A majority of patients with otosclerosis will present with bilateral hearing loss. Evaluation of patients involves the Rinne and Weber tests, audiometry, and CT imaging. Clinically, patients will present with hearing loss and, less commonly, tinnitus and vertigo. Histologically, increased osteoblasts and osteoclasts are seen with the presence of abnormal sclerotic bone. The pathologic process involves new bone formation and proliferation of the vasculature. The hardening of the structures results in loss of flexibility and ultimately prevents the stapes footplate from transmitting oscillations to the oval window. Otosclerosis is defined as abnormal bony growth starting in the bony labyrinth and oval window moving toward the auditory ossicles leading to conductive hearing loss. There are two muscles of the ossicular chain, namely the tensor muscle of the tympanum or malleus and the stapedius or stapes muscle. The ossicular chain is held in its position by the connections of the malleus handle with the tympanic membrane, the annular ligament of the stapes, and the ligaments of the malleus and incus. The incudomallear joint is a saddle joint, which starts to move with sounds starting at 2 kHz. On average, the malleus has a height of about 8.0 millimeters and about 2.7 millimeters in width the incus has about a height of 6.8 millimeters and a width of about 5.3 millimeters the stapes has a height of about 3.5 millimeters and a width of about 2.4 millimeters. The stapes has an angle of approximately 10.7 degrees to the surface of the tympanic membrane. Incudostapedial joint (ISJ) is organized as a synovial joint, with the presence of a meniscus and intra-articular fluids, a capsule the joint has the typical characteristics of a viscoelastic joint. The tympanic membrane vibrates, leading to the movement of the chain of ossicles. The attachment of the footplate of the stapes to the oval window allows the displacement of fluid within the inner ear. The sound waves initially make contact with the external ear and tympanic membrane. The main function of the middle ear is to transmit the sound waves from the external environment to the inner ear. The stapes articulates with the oval window of the inner ear. It is known as the smallest bone within the human body. The stapes is the third ossicle and consists of the head, legs, and footplate. The incus connects with the stapes and forms the incudo-stapedial joint. The incus is the second ossicle and is divided into the body, short process, and long process. The head of the malleus attaches to the incus and forms the incudo-malleolar joint. The handle of the malleus attaches loosely to the tympanic membrane. It is divided into four parts: the head, neck, short process, and handle.

The malleus is the first ossicle and attaches to and moves with the tympanic membrane. These three ossicles connect the tympanic membrane to the inner ear allowing for the transmission of sound waves. The middle ear consists of the tympanic membrane and the bony ossicles called the malleus, incus, and stapes. The ear structures are classically divided into three parts: the external ear, middle ear, and inner ear.

Auditory ossicles function