The ear, nose, throat, and eye

chapter 8

otorhinolaryngology

• the study of ear, nose, throat. (ENT)

Pinna

• is the external visible part of the ear

• its used more in zoology and its synonyms is auricle

auricle

• is the external visible part of the ear

• correspondence with pinna but its more a medical term.

external auditory canal constitute

• an s shaped passage in the temporal bone that channel sounds waves from the auricle to the tympanic membrane (eardrum).

ceruminous glands

• located in the auditory canal and it secretes cerumen or earwax.

• earwax protects the inner structures of the ear from foreign particles.

External ear (5)

• pinna, auricle, external auditory canal, and tympanic membrane.

tympanic cavity

• An air-filled chamber extending from the tympanic membrane

• It transmits and amplifies sound vibrations from the eardrum to the inner ear

• it seperates the external ear from the middle ear.

ossicles

• the three smallest bones in the human body

  • malleus - the first and largest (9mm)

  • incus - the middle (7mm)

  • stapes - the smallest bone in the human body (2-3mm)

malleus

• the first and largest ossicles (9mm)

incus

• the middle ossicles (7mm)

stapes

• the smallest bone in the human body (2-3mm)

eustachian tube

• connects to the nasopharynx and opens into the middle ear cavity.

• a narrow passage made of bone and cartilage that connects your middle ear to the back of your nose and upper throat.

• it helps equalize air pressure, drain fluids and proects the ear from bacterria and germs.

nasopharynx

• the uppermost part of the throat (pharynx) and its located directly behind the nose and just above the soft palate (roof of the mouth)

tympanic membrane

• conducts the sound waves carried to it through the external auditory canal. The sound waves are then transmitted to the bony ossicles in the oval window.

Middle ear (5)

• tympanic cavity, malleus, incus, stapes, and eustachian tube

cochlea

• spiral, snail shaped, fluid filled bony structure in the inner ear that converts mechanical sounds waves into electrical nerve signals for the brain.

• signals are transmitted through the cochlear branch of cranial nerve VIII to the brain

organ of corti

• pimrary receptor organ of hearing and its made up of hair like sensory cells surronded by senosry nerve fibers.

• located inside the cochlea.

semicircular canals

• three tiny fliud filled loop structure in the inner ear within the temporal bone.

• help to evaluate the position of the head in relation to the pull of gravity and maintain balance

• lateral (horizontal) canal - shaking head

• anterior (superior) canal - nodding

• posterior canal - tilting head towards shoulder

vestibule

• central cavity of the bony labyrinth in the inner ear

• includes sensory organs in your inner ear that help you maintain your sense of balance.

• it directs linear acceleration, senses head tilt through gravity, and it maintains balance and equilibrium.

inner ear (3)

• cochlea, semicircular canals, and vestibule

larynx

• also known as the voice box

• it is a hallow muscular and cartilaginous organ located in the front of the neck, situated between the upper throat (pharynx) and the windpipe (trachea)

• three parts:

  • supraglottis - includes epiglottis

  • glottis - sound production

  • subglottis

Anterior naris (nostrils)

• external opening to the nasal cavity.

inferior concha

• regulates the air that is being breathed in.

Nasal cavity

• It serves as the main entrance to the upper respiratory system

• large air filled space above and behind the nose in the middle of the face.

Parts of the nasal cavity and throat (5)

• the larynx, pharynx, nasopharynx, nostrils, and inferior concha

Hearing Loss

• Conduction problems (related to sound waves within the ear) and sensorineural impairments may cause this.

• conduction problems:

  • preventing the passage of sound vibrations through the external auditory canal

  • Conditions limiting the vibration of the tympanic membrane

  • Conditions interfering with the passage of bone-conducted sound in the middle ear

• Sensorineural problems include:

  • Abnormality in the organ of Corti

  • Auditory nerve problems

Presbycusis

• hearing loss due to a loss of receptor cells in the organ of corti due to aging.

Otitis

• infection or inflammation of the ear

otitis externa (swimmers ear)

• is the infection of the external ear due to dermatologic conditions, such as seborrhea or psoriasis, trauma to the canal, or continuous use of earplugs or earphones.

Otitis media

• is an inflammation of the middle ear resulting in accumulation of fluid behind the tympanic membrane.