Ears: Anatomy, Function, Diseases

In the following, “ears” describes diseases that are assigned to this category according to ICD-10 (H60-H95). The ICD-10 is used for the International Statistical Classification of Diseases and Related Health Problems and is recognized worldwide.

Ears

The human ear is a sensory organ. It combines the sense of hearing and the sense of balance, and thus are important for perception and orientation.

Anatomy

The ear is divided as follows:

  • Outer ear (auris externa).
    • Auricle (Auricula auris)
    • External auditory canal (meatus acusticus externus)
    • Tympanic membrane (Membrana tympani) – separates the outer ear from the middle ear.
  • Middle ear (auris media) – air-containing bone cavities.
    • Tympanic cavity
      • Lies behind the eardrum
      • Contains the three ossicles malleus (hammer), incus (anvil), stapes (stirrup).
    • Eustachian tube (Tuba auditiva) (synonym: Eustachian tube) – connects the tympanic cavity with the nasopharynx (epipharynx, pars nasalis pharyngis or rhinopharynx).
  • Inner ear (Auris interna)
    • The inner ear is located in the petrous bone (pars petrosa ossis temporalis), at the base of the temporal bone (Os temporale).
    • It consists of a complex system of small bone cavities in which duct systems are embedded. Because of its appearance or arrangement, it is called a “labyrinth”.
    • According to function, a distinction is made between the cochlear labyrinth (labyrinthus cochlearis), which contains the actual organ of hearing (organ of Corti), and the vestibular labyrinth (labyrinthus vestibularis), which contains the organ of balance:
      • Cochlea of hearing (cochlea)
        • Contains hair cells that register sound vibrations; at their base are nerve fibers that transmit information to the brain via the auditory nerve (cochlear nerve (acusticus))
      • Vestibular organ (organ of balance).
        • Consists of three semicircular canals (arcades; canales semicirculares ossei) and an atrium (vestibulum labyrinthi); sensory cells are located in both areas
        • In the atrium are two small sensory organs that form the so-called otolith apparatus. They contain beet-like arranged sensory cells, on which fine crystals, the otoliths, are located.
        • From the sensory cells, the sensory information reaches the VIII. Cranial nerve (Nervus vestibulocochlearis) to corresponding nerve nuclei in the brainstem (vestibular nuclei).

Physiology

The outer ear and middle ear are also known as the sound-conducting apparatus. The human ear can perceive sound waves in the range of 16 to 16,000 hertz. Below or above this range, sound waves are in a range that is inaudible to humans. The outer ear picks up the sound waves and transmits them through the ear canal to the eardrum. Along the way, the outer ear allows humans to determine the direction from which the sound is coming. The eardrum transmits the sound vibrations to the three auditory ossicles: the malleus, incus and stapes. Finally, the sound waves reach the cochlea (inner ear), where they are converted into nerve impulses. This excitation of the auditory nerve is then perceived by the part of the cerebrum responsible for hearing (auditory cortex) as speech, sound or tone. In addition to the hearing organ, the inner ear also houses the organ of balance. This registers the position and movement of the head and enables orientation in space. By means of the otolith apparatus, linear accelerations in the horizontal and vertical planes are detected, i.e. acceleration, braking, climbing and falling are perceived. Through the arcades, rotational accelerations of the head are detected.

Common diseases of the ears

How much well-being and quality of life depend on well-functioning hearing is often not noticed until ear health is compromised. The most common ear diseases include:

  • Hearing loss
  • Hypacusis (hearing loss)
  • Meniere’s disease – inner ear disease that causes acute attacks of dizziness, ringing in the ears and hearing loss.
  • Otalgia (ear pain)
  • Otitis externa (inflammation of the auditory canal)
  • Otitis media (inflammation of the middle ear)
  • Otosclerosis – progressive disease of the ears associated with excessive bone formation of the bony labyrinth (small bone cavity system).
  • Tympanic effusion (synonym: seromucotympanum) – accumulation of fluid in the middle ear (tympanum).
  • Presbycusis (age-related hearing loss)
  • Tinnitus (ringing in the ears)
  • Perforation of the eardrum / rupture of the eardrum (rupture of the eardrum)
  • Vertigo (dizziness)

The main risk factors for ear disease

Behavioral causes

  • Psycho-social situation
    • Stress

Causes related to disease

Environmental pollution – intoxications (poisonings).

  • Noise

Please note that the enumeration is only an extract of the possible risk factors. Other causes can be found under the respective disease.

The most important diagnostic measures for ear diseases

  • Audiometry (hearing test)
  • Balance test
  • Hearing aid check
  • Otoscopy (ear examination)

Which doctor will help you?

Simple acute diseases of the ears usually do not need to be treated by a doctor of otolaryngology (ENT). This is where the primary care physician becomes involved. If it is a more severe course of acute diseases or chronic diseases of the ears is referred to an otolaryngologist in the majority of cases.