Ear Flashcards
What does the external ear do
Collects and conveys sound waves to tympanic mem
What is the middle ear and what does it do
Tympanic mem to oval window
Eustanchion tube
Amplifies and conducts sound waves to internal ear
What is the internal ear and what does it do
Oval window to internal acoustic meatus
Converts special sensory information
- -> sound waves to fluid waves
- -> then action potentials
- -> conduct action potentials to Brian
What kind of cartilage is the external ear
Elastic
What does the a vascular property mean to the external ear
Take nutirents form skin
Why do you not use adrenaline anaesthetic on ear
Adrenaline causes vasoconstriction causing necrosis of the avasvilar tissue as this tissue requires nutirents form skin and its blood supply
Describe the ER canal
Eam
1/3 rd cart 2/3rds bony
Lined skin v thin
Produce earwax cerumin via ceruminous gland
Give three features of the external auricle
Helix
Tragus
Lobe
What is the general sensory innervation of the external ear
Superior parts eam and tympanic mem - CN V3 mandibular nerve
Inferior parts eam and tympanic mem - vagus nerve
Lower part of helix almost lobe - C2,3 spinal nerve
Inside part of helix - facial nerve
Top of helix - C2,3 spinal nerve
Explain the lymphatic drainage of the ear
Lateral surface of superior half - parotid lymph nodes
Cranial surface of superior half - mastoid lymph nodes and deep cervical
Rest of auricle including lobe - superficial cervical lymph nodes
Where does the lymphatic drainage eventually drain to
Deep cervical lymph nodes in carotid sheath
Thoracic duct or right lymphatic duct
Venous angle
What is an otoscopic examination
Examination of the eam and tympanic mem
How do you carry out an otoscopic examination of a child
Eam is short and straight
Do not damage tymp meme so be v careful
Gently pull auricle posteroinferiorly
How do you carry out an otoscopic examination of an adult
Eam is curved
Gently straiten eam
Gently pull auricle posterosuoeriorly
What is the pars flaccida
Thin part of tymp mem superiorly
What so the pars tense
Thick part of the tympanic mem posteroinferiorly
What is the umbo
Most inwardly depressed part of tymp mem
Where is the cone of light
NormLly directed anteriorinferiorly
What is the sensory innervation of the tymp mem
External - mostly V3 auriculotemporal branch
Internal - CN IX
Where does the Glossopharyngeal nerve IX supply sensory innervation to in the ear
Middle ear cav Eustanchion tube Nasopharynx Oropharynx Tonsils
What does the Eustachian tube connect
Connects the tymp cav to lateral wall of nasopharynx
What are the auditory ossicles
3 bones of Middle ear cav articulate via synovial joints
Name the Auditory ossicles
Malleus
Incus
Stapes
What is the epitympanic recess
Sup to tymp mem
What is the base of the stapes
Fits into oval window way into internal ear
What creates the umbo
The handle of the malleus adherent to internal aspect of the tymp mem
What is the aditus
Doorway to the mastoid process
What is the right promontory
Bony swelling on medial wall formed by the cochlea of internal ear
What is mastoiditis
Air cells in mastoid become infected due to spread of infection
Explain what the facial nerve does and it’s course
Special sensory taste
General sensory
Motor
Parasymp
Connection to CNS - brain stem at junction between pins and medulla PONTOMEDULLARY JUNCTION
inter cranial corse - direct into iam in posterior cranial fossa
Base of skull foramen - iam and the stylomastoid foramen
What is the chords tympani
Branch of the facial nerve
Supplies taste on anterior 2/3rd of tongue
Parasymp to submand and subling salivary glands
What is significant about the right stapedius
Tiniest skeletal muscle in body suppli by facial nerve
Reduces stape movement to protect internal ear from excessive noise
What does the tensor tympani do
dampens noise of chewing supplied by facial nerve
What is the facial nerve extra cranial course
Exit cranial cav via internal acoustic meatus
Facial nerve through stylomastoid foramen
Chordae tympani branch connects to lingual nerve branch of V3 to supply parasymp secretomotor to submandibular and sublingual glands
Facial nerve supply muscles of facial expression
What are some muscle of facial expression
Frontalis
Orbicularis oculi- oris
Elevators of lip
What do facial expression muscles do and originate from
Originate - on bone and insert into superficial fascia
Pull on skin when contracted
How can u clinically test facial expression and motor function of facial nerve
Ask pt to Frown Close eyes tight Smile Puff out cheeks
What is the buccal fat pad
On Buccinator
Loss in illness - sunken cheeks clinical sign of malnutrition
What is the vermillion border
Border between skin and fascia of lips transition zone
What are the two parts of the vestibulocochlear nerve
Cochlear nerve - hearing
Vestibular nerve - balance
What does the otic capsule contain
Bony labyrinth
What does the bony labyrinth filled with
Fluid peri lymph filled
Spaces inside otic capsule
What is suspended within the perilymph of the bony labyrinth
Membranous labyrinth
Communicating sacs and ducts
Contains endolymph fluid
Where does the dense otic capsule sit
Temporal bone
What su the perilymph
Fluid that fills the bony labyrinth
The ,ends nous labyrinth floats in bony labyrinth
What are the two windows of the bony labyrinth
Oval and round
What is the cochlear duct and what does it do
A long balloon like strict within the cochlea filled with endolymph
Action pots conducted to brain stem in cochlear nerve
What are the semi circular ducts
Inter linked balloon like structures within semicircular canals filled with endolymph
Action potentials conducted to brain stem in vestibular nerve
What is the sequence of sound transmission
1- sound waves make tymp mem vibrate
2- vibrations transmit through ossicles
3- base of stapes vibrates in oval window
4- vibration of stapes creates pressure waves in perilymph
5- hair cells in cochlea are moved neurotransmitter is released, action potentials stimulated and conveyed to brain by cochlear nerve
6- pressure waves descend and become vibrations again
7- pressure waves dampened at the round window
What is the course of the vestibulocochlear nerve
CN 7 and CN 8 connect with brains team at the junctions between pons and medulla oblongata
Vestibulocochlear nerve at internal acoustic meatus
Cochlear axon nerves
Vestibular nerve axons form semicircular ducts
What are some symptoms of pathology of CN vii in internal acoustic meatus
Ipsilateral- loss facial expression, loss of taste
Dry mouth
Reduced sensation in auricle
What are the symptoms of associated pathology internal acoustic meatus of CN viii
Ipsilateral- loss of hearing, loss of balance
What does the external part of the ear compose of
Auricular piña to tympanic mem drum
Lead to eam
