Ear anatomy and physiology Flashcards
What bone contains everything to do with the ear?
Temporal
What are the three anatomical divisions of the ear?
External
Middle
Internal
What functions does the ear play?
Hearing and balance
Where are the temporal bones found?
Lateral side of head
Inferior to parietal bone and posterior to sphenoid bone
Name four important lateral parts of the temporal bone
Styloid process
External auditory meatus
Mastoid process
Zygomatic process
What links the temporal bone with the zygomatic bone?
Zygomatic process of temporal bone and temporal process of zygomatic bone
Name three important parts on the inferior temporal bone
Mandibular fossa
Stylomastoid foramen
Extracranial opening into carotid canal
Name an important opening in the internal part of the temporal bone
Internal acoustic meatus
What passes through the stylomastoid foramen?
CNVII
Where does CNVII pass?
Stylomastoid foramen
What foramen is found between the temporal and occipital bones?
Jugular foramen
What passes through the internal acoustic meatus?
CNVII
CNVIII
Labyrinthine artery and vein
What does CNVII (facial) do?
Motor to face and stapedius
Ant 2/3 of taste
Secretory to lacrimal and salivary glands
General sensation to external ear
What does CNVIII (vestibulococlear) do?
Special sense from ear
Where does the labyrinthine artery arise from?
Circle of Willis
What is the job of the external ear?
To collect sound
What is the job of the middle ear?
To amplify sound
What if is the job of the inner ear?
To create sensory signals
What nerves supply sensory to the majority of the pinna?
Spinal nerves C2+3
What cranial nerves supply sensory to the external ear?
V3. VII and X
Where in the external ear does V3 supply?
Most of superior around tragus and head.
Superior EAM and most of tympanic membrane
Where in the external ear does VII supply?
A smattering in concha
Where in the external ear does X supply?
Concha
Inferior EAM and part of tympanic membrane
Describe the lymphatic drainage of the external ear
Superior lateral- parotid
Superior cranial- Mastoid
Rest- superficial cervical
Where do all the lymph nodes of the head eventually drain?
Deep cervical lymph nodes
What are the four important parts of the tympanic membrane?
Pars flaccida- Thinnest part and most superior
Pars tensa- Most of it and inferior
Cone of light- Anterior
Umbo- Part of malleus and slopes posterior
How can you tell the orientation of an ear from the tympanic membrane?
Umbo slopes backwards and cone of light anterior.
Which nerve supplies sense to the middle ear and eustachian tubes?
CNIX (glossopharyngeal)
What are the three bones of the middle ear?
Malleus
Incus
Stapes
What two muscles are found in the middle ear?
Tensor tympani
Stapedius
What kind of joint links the ossicles?
Synovial
What is the superior part of the middle ear called?
Epitympanic recess
What links the inner ear with the nasal cavity?
Eustation tubes
What links the middle ear with the inner ear?
Oval and round windows
What two nerves pass through the middle ear?
CNVII
Chorda tympani
What is the chorda tympani a branch of?
CNVII
is CNVII or the chorda tympani more lateral?
Chorda tympani
Describe the route of CNVII
Exit cranium via eternal acoustic meatus
Enter then leave middle ear in facial canal of middle ear
Leaves temporal bone vie stylomastoid foramen
Where does the Eustachian tube enter the pharynx?
Nasopharynx inferior to adenoids
What nerve supplies the naso/oropharynx, Eustachian tubes and middle ear?
CNIX (glossopharyngeal)
What does the stapedius muscle do?
Reduces movement to protect inner ear from loud noises
What does the chorda tympani do?
Ant 2/3 taste
Submandibular and lingual salivary glands
What are the muscles of facial expression (4 of them)?
Frontalis
Orbicularis oculi
Elevator of lips
orbicularis oris
How do you test the muscles of facial expression?
Frontalis- Frown
Orbicularis oculi- Close eyes tight
Elevator of lips- Smile
orbicularis oris- Maintain puffed out cheeks
What bony structure contains the inner ear?
Otic capsule
What fluid is found in the otic capsule?
Perilymph
What floats in the perilymph?
Membranous labyrinth
What is contained in the Membranous labyrinth?
Endolymph
Which is more superior the round or oval window?
Oval
What three parts are there to the labyrinths?
Cochlear ducts
Semicircular ducts
Utricles and saccules
What parts make up the vestibular system?
Semicircular ducts
Utricles and saccules
What do Utricles and saccules do?
sense lineal movement
What do semicircular ducts do?
Sense angular movement
What is found at the entrance to all semicircular canals?
Ampula
How many semicircular canals do we have?
3 each side
What are the three compartments of the cochlear apparatus?
Scala media
Scala vestibuli
Scala tympani
Where is perilymph found?
Scala vestibuli and tympani
Where is endolymph found?
Scala media
What is found in the scala media?
Basilar membrane
Where does the vestibulocochlear (CNVIII) enter the skull?
Internal acoustic meatus
Where does CNVIII join the brain stem?
Pontomedullary junction
How does the ear sense sound?
vibrations pass through the oval window into the scala vestibuli.
Pass along here vibrating the basilar membrane activating the organ of Corti.
Different parts of the BM detect different frequencies etc
Vibration passes out via round window.
What are the three semicircular canals called?
Horizontal- Flat. Apex lateral
Superior- Going up. Apex superior
Posterior- Going back. Apex posterior
Where are hair cells in the semicircular canals found?
Ampula
What provides a reference for the stereocilia/hair cells in the ampulla?
Kinocilium
How do the saccules and utricles sense linear movement?
Otolith crystals bend the cilia causing depolarisation.
What cell type lines the external auditory canal?
Stratified epithelium- skin
What special glands are found in the skin of the ear?
Sebaceous and ceruminous- produce earwax
What cell type is found in the middle ear?
Columnar lines mucosa
