ENT Anatomy

Pinna

Auricle (external ear)

Pinna function and clinical significance

-localizes, concentrates and directs air vibrations into the auditory canal

-trauma, sun exposure (cancer)

Auditory Canal function

-transmits sound vibrations from outside to the tympanic membrane

-protects middle and inner ear structures

-ceruminous glands produce cerumen that works to repel insects and trap foreigh bodies

Swimmer's Ear

-Auditory Canal

-infection- otitis externa

-sx: tenderness to tragus touch, swollen walls of ear canal, discharge

Middle Ear

-The cavity in the temporal bone that contains the ossicles

-Extends from the tympanic membrane to the cochlea

-Ventilated by the Eustacian Tube

Ossicles

-maleus

-incus

-stapes

Tympanic membrane function

-vibrates in response to sound (air) waves hitting external surface --> transmits vibration to ossicles

Cone of light

seen in healthy ears, reflection of your light

Myringotomy tubes

common in children; recurrent otitis media, typically fall out on their own

Tympanic membrane --> oval window

-ear ossicles transmit vibrations mechnically

-TM attached with the malleus attaches to the incus attaches to the stapes attached to the membranous oval window of the inner ear

-transition from an air filled space to a fluid filled one

stapedius

reduces mobility of stapes

tensor tympani

pulls eardrum inward, tightening it

Eustachian tube of the middle ear is connected to

-nasopharynx- which fills the cavity with air

-ET usually closed and flattened, opens with yawning

Horizontal and vertical orientation of the ET

-Horizontal: infants

-Vertical: as we age it becomes more vertical which makes it harder for bacteria to enter, hence why adults have less otitis media

Otosclerosis

stapes has a bony fixation and difficult to transmit vibration to cochlea

tympanosclerosis

scarring of tympanic membrane (often from tubes); usually does not affect hearing

Serious otitis media

collection of fluid in the middle ear (clear,serous fluid that can be seen behind tympanic membrane) --> seen in early ear infection or clearing ear infection

-can see bubbles

labyrinth

-the inner ear

-bony covering and membranes within

3 sections of the labyrinth

1. the vestibule

2. the semicircular canals

3. the cochlea

Vestibule

-balance and equilibrium

-central cavity of the bony labyrinth

-saccule and utricle

maculae

equilibrium receptor regions that respond to the pull of gravity and changes in head position

-gravitational equilibrium

semicircular canals

-balance and equilibrium

-inner ear contains an anterior, posterior and lateral semicircular canal

-within each canal is a semicircular duct

-each duct has an ampula at one end that has equilibrium receptors in it that responds to the movement of the head

semicircular duct

communicate with the utricle anteriorly

*utricle is in the vestibule and in the equilibrium receptor regions called maculae that respond to the pull of gravity and changes in head position

cochlea

-sensation of hearing

-fluid filled

-spiral organ of Corti, which is the receptor organ for hearing

-floor is composed of the basilar membrane, which plays an important role in sound reception (stimulates hair cells which send action potentials to the brain)

Receptor organ for hearing

Spiral organ of Corti

Otolith

-ear stone

-stimulates mechanically stimulated hair cells that transmit signal to brain

Benign paroxysmal positional vertigo

otolith somewhere it shouldn't be

Rotational equilibrium

-semicircular canals

-maintaining balance when the head or body is rotated, moved suddenly

-detects changes in direction and the rate

ampula

area where the cupula is located

cupula

a cap where the hair cells are located

Physiology of hearing

-eardrum vibrates easily

-oval window vibrates the endolymph in the scala vestibuli

-fluid wave in the scala tympani stretches the basiliar membrane which causes the basiliar membrane to oscillate which causes the organ of corti hair cells (stereocilia) to bend or move which, depending on the location within the cochlea and the intensity of the sound, causes the hair cells to form action potential which causes the cochlear nerve to be stimulated and sending a signal to the brain

tracts of the olfactory nerve

lead to the temporal lobe, amygdala, hypothalamus

3 pairs of extrinsic salivary glands

-connected to oral cavity by ducts

-Wharton's duct: opening of the submandibular duct, under the tongue, one on each side of frenulum

-stenson's duct: opening of the partoid duct seen on the inner cheek

-multiple openings of the sublingual gland into the mouth

Wharton's duct

opening of the submandibular duct under the tongue on either side of frenulum

Stenson's duct

opening of the parotid duct seen on the inner cheek

lingual lipase

digests fat after reaches the stomach

immunoglobin A

inhibits bacterial growth

furrow

saliva-filled depression delimiting the lingual taste buds

foliate papilla

taste bud located mainly on the posterior lateral edges of the tongue and having a taste function

fungiform papilla

mushroom-shaped taste bud occurring in large numbers at the apex and on the sides of the tongue and having a taste function

circumvallate (vallate) papilla

each of the large taste buds forming a lingual V at the back of the body of the tongue ensuring the taste function

filiform papilla

cone-shaped taste bud covering the rear of the tongue

function is solely tactile

give the tongue its velvety appearance

Vagus Nerve (X)

some taste bud innervation root of tongue, epiglottis and pharynx

Facial nerve (VII)

anterior 2/3 of the tongue

Glossopharyngeal nerve (IX)

posterior 1/3 of tongue

chemical receptors are responsible for 5 tastes (salty, sweet, sour, bitter and umami)

sodium, potassium, chloride, adenosine, inosine, sweet, bitter, glutamate, hydrogen ion

Roof lining of nasal fossa

olfactory mucosa

meatuses

air passages beneath each conchae

narrowness and the turbulence ensures that the air contacts the mucous membranes