Assessment of the Ears

Auricle or pinna

External auditory canal

The external ear includes:

tympanic membrane

Separates the external ear from the middle ear. About 1 cm in diameter, Very thin, Normally pearly gray and Translucent. Conducts sound vibrations from the external canal to the ossicles. Sound pressure is magnified about 22 times as it moves from a larger area to a smaller area.

auricle, or pinna

the visible part of the ear attached to the side of the head. Mainly made of Cartilage and Skin. Collects sound waves and directs sound vibrations into the external auditory canal

External Auditory Canal

the passageway that carries sound from the auricle to the tympanic membrane. It is approximately 2 to 3 cm long.

Cerumen

helps protect the ear canal by trapping dirt, dust, and small foreign materials.

Middle Ear

an air-filled cavity that includes Tympanic membrane laterally, Otic capsule medially, and an ear cleft between them. It is connected to the nasopharynx through the eustachian tube.

Eustachian Tube

A narrow tube between the middle ear and the throat that serves to equalize pressure on both sides of the eardrum. Approximately 1 mm wide and 35 mm long. Drains normal and abnormal secretions from the middle ear

Valsalva maneuver

Yawning

Swallowing

The eustachian tube is normally closed. It opens during:

tensor veli palatini muscle.

The opening of eustachian tube occurs through the action of the

Outer layer - Continuous with the skin of the ear canal

Middle fibrous layer

Inner mucosal layer - Continuous with the lining of the middle ear cavity

Layers of the Tympanic Membrane

Pars Tensa and Pars Flaccida

Parts of the Tympanic Membrane

Pars Tensa

the thicker and more taut part of the tympanic membrane. Makes up approximately 80% of the tympanic membrane. Contains all three layers. More stable and firm

Pars Flaccida

small, slack, superior section of tympanic membrane. Makes up approximately 20% of the tympanic membrane, Lacks the middle fibrous layer. More vulnerable to pathologic disorders

Annulus

the fibrous border that attaches the eardrum to the temporal bone.

Umbo

central part where the malleus attaches to the tympanic membrane.

ossicles (malleus, incus, stapes)

the three smallest bones in the body located in the middle ear. help transmit sound vibrations from the tympanic membrane to the inner ear. They are held in place by:

Joints, Muscles, Ligaments. Acts like a lever system that transfers mechanical energy to the oval window.

Oval window

Round window

There are two small openings, or fenestrae, in the medial wall of the middle ear. These separate the middle ear from the inner ear.

Oval Window

membrane at the entrance to the cochlea through which the ossicles transmit vibrations. Where the footplate of the stapes moves.

Round Window

located just below the oval window covered by a thin membrane; equalize pressure in the inner ear. It provides an exit for sound vibrations.

Inner Ear

located deep within the temporal bone. It contains organs responsible for: Hearing and Balance

Cochlea

Semicircular canals

Cranial nerve VII, or facial nerve

Cranial nerve VIII, or vestibulocochlear nerve

Important Structures in the Inner Ear

Bony Labyrinth

winding tunnels located in the inner ear. Houses the cochlea and semicircular canals. It surrounds and protects the membranous labyrinth.

Perilymph

the fluid surrounding the membranous labyrinth.

Utricle

Saccule

Cochlear duct

Semicircular canals

Organ of Corti

The membranous labyrinth is composed of:

Endolymph

the fluid found inside the membranous labyrinth.

Posterior semicircular canal

Superior semicircular canal

Lateral semicircular canal

The three semicircular canals; They lie at 90-degree angles to one another.

Semicircular canal

Detect rotational movement. They are stimulated by changes in Rate of movement and Direction of movement. The semicircular canals help maintain balance during head rotation.

Utricle and Saccule

two specialized sensory organs in the inner ear's vestibular system. Known as otolith organs, they are crucial for maintaining balance, detecting gravity, and sensing linear acceleration

organ of corti (spiral organ)

the organ of hearing consisting of supporting cells and hair cells that rest on a basilar membrane & extend into the endolymph of the cochlear duct. Transforms mechanical energy into neural activity. Separates sounds into different frequencies. Sends impulses through the acoustic nerve to the brain

Cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses. It is about 3.5 cm long and has 2.5 spiral turns

Scala media, also called the cochlear duct

Scala vestibuli

Scala tympani

The cochlea is a snail-shaped, fluid-filled cavity in the inner ear that contains three parallel compartments

Cochlear nerve: Comes from the cochlea; Responsible for hearing

Vestibular nerve: Comes from the semicircular canals, utricle, and saccule; Responsible for balance

The vestibulocochlear nerve has two parts:

Hearing

the process by which sound waves enter the ear, are transmitted through ear structures, and are converted into nerve impulses that the brain interprets as sound.

Air Conduction

the normal pathway of hearing where sound travels through the air-filled external and middle ear. normally the more efficient pathway for hearing.

Bone Conduction

occurs when sound travels directly through the bones of the skull to the inner ear. Bypasses the tympanic membrane and ossicles

Stapes

receives sound impulses from the incus and malleus. The footplate moves at the oval window. This movement creates waves in the inner ear fluids.

Balance and equilibrium

refer to the body's ability to maintain position, posture, and stability. depends on the coordination of different body systems.

Proprioceptive system

Visual system

Vestibular system

Cerebellar system

Cardiovascular system

Balance is maintained by cooperation of:

Proprioceptive System

monitors information about the position of the body that comes from receptors in the muscles, joints, and organs of balance

Vestibular System

The sensory system that responds to gravity and keeps people informed of their body's location in space. Gives feedback about Head movement, Body movement, and Position of the head and body in space

Cerebellar System

coordinates balance information and helps perceive body position and movement

Vestibular Apparatus

equilibrium receptors in semicircular canals and vestibule

Acute external otitis

If moving or manipulating the auricle causes pain, suspect:

Gross auditory acuity

refers to a general assessment of the patient's hearing ability. It helps determine whether the patient can hear sounds or spoken words clearly.

Whisper Test

a simple screening test used to assess hearing acuity. Test one ear at a time. Cover the untested ear with the palm of the hand. Stand about 1 to 2 feet away from the ear being tested. Stay out of the patient's sight.

Weber Test

uses bone conduction to determine whether sound is heard equally in both ears or lateralizes to one ear. Hold the tuning fork by the stem. Activate it by tapping it on the examiner's knee or hand. Place the stem of the vibrating tuning fork on the patient's forehead. It should be heard equally in both ears or centered in the middle of the head. Useful for detecting unilateral hearing loss.

Conductive Hearing Loss

hearing impairment caused by interference with sound or vibratory energy in the external canal, middle ear, or ossicles. failure in the vibration of the eardrum and/or movement of the ossicles. Sound is heard better in the affected ear (sound goes to the bad ear)

Sensorineural Hearing Loss

the most common form of hearing loss, also called nerve deafness; caused by damage to the cochlea's receptor cells or to the auditory nerves. Sound is heard better in the normal or better-hearing ear.

Rinne Test

compares air conduction and bone conduction. It helps distinguish conductive hearing loss from sensorineural hearing loss.

Audiometry

the most important diagnostic tool for detecting hearing loss. It measures how well a person hears sounds.

Pure-Tone Audiometry

Speech Audiometry

Two Types of Audiometric Testing

Pure-Tone Audiometry

This uses a pure or musical tone. The louder the tone must be before the patient hears it, the greater the hearing loss.

Speech Audiometry

This uses spoken words to determine the patient's ability to Hear sounds, Discriminate words, Understand speech

Frequency

Pitch

Intensity

When evaluating hearing, three characteristics are important:

20 to 20,000 Hz

The normal human ear can hear sounds from:

Audiogram

A graphic representation of the relation of vibration frequency and the minimum sound intensity for hearing. Helps differentiate conductive from sensorineural hearing loss.

Tympanogram

also called impedance audiometry, measures Middle ear muscle reflex to sound stimulation and the Compliance of the tympanic membrane

Auditory Brain Stem Response Audiometry

The technique of recording the electrical activity of the auditory nerve and the brain stem in response to various sound stimuli

Electronystagmography

is the measurement and graphic recording of electrical changes created by eye movements. It is used during Spontaneous nystagmus, Positional nystagmus, or Calorically evoked nystagmus. Assesses the Oculomotor system, Vestibular system, and the Interaction between eye movement and balance mechanisms

Avoid for 48 hours: Caffeine, Alcohol, Vestibular suppressants

Withhold for 5 days if ordered: Tranquilizers, Stimulants, Antivertigo medications

Patient Preparation

Before Electronystagmography

Platform Posturography

a test used for patients with

Dizziness, and Balance disorders. For diagnosing balance (vestibular) impairment; step on the plate, put on a safety harness, and try to stand up for 20 minutes. Preparation is the same as for electronystagmography.

Sinusoidal Harmonic Acceleration

Also called a rotary chair test. This test measures eye movements in response to chair rotations for the evaluation of vestibular function. This test may be conducted for patients that have been experiencing dizziness, vertigo or balance problems. Patient sits in a chair that rotates: Clockwise and Counterclockwise. The test analyzes compensatory eye movements in response to rotation. It helps identify disorders such as Ménière's disease

and Tumors of the auditory canal

Middle Ear Endoscopy

a procedure that uses small-diameter endoscopes to examine the middle ear. It is performed by an endoscopist specializing in otolaryngology.