The Ear Flashcards
What are the three divisions of the ear
External, middle and internal
What is the external ear composed of
The auricle, external auditory meatus and the external surface of the tympanic membrane
What is the middle ear composed of
The internal surface of the tympanic membrane, tympanic cavity, ossicles and pharyngotympanic tube
What is the internal ear composed of
Auditory meatus, vestibular apparatus, internal auditory meatus, vestibulocochlear nerve, oval window and round window
What is the auricle composed of
Elastic cartilage
What controls the auricle
Muscles of facial expression
Where does lymph from the auricle drain to
The parotid and cervical lymph nodes
What supplies the auricle with blood
Superficial temporal, anterior auricular, posterior auricular and perforating branches
What innervates the auricle
CN V3, CN XI, CN VII and the lesser occipital and greater auricular nerves from the cervical plexus
What is the external auditory meatus composed of
Lateral 1/3rd - elastic cartilage, hair follicles, sweat and sebaceous glands
Middle 2/3rd - bone lined with stratified squamous epithelium
Blood supply of the external auditory meatus
Auricular branch of the external carotid
Innervation of the external auditory meatus
Mainly from the auriculo-temporal from CN V2 but also supplied by auricular branch from CN VII and CN X
What is the outer surface of the tympanic membrane covered by
Stratified squamous epithelium
What is the inner surface of the tympanic membrane covered by
Mucous membrane
Where is the chorda tympani found
On the medial surface of the tympanic membrane
What attaches to the inner surface of the tympanic membrane
The malleus
What innervates the lateral surface of the tympanic membrane
Tympanic branches of the glossopharyngeal nerve
What is the combined action of tensor tympani and stapedius
To reduce the vibrations passing to the delicate inner ear
What supplies the tympanic cavity with sensory innervation
CN XI
What provides the tympanic cavity with blood
Mostly from tympanic branches of the posterior auricular, ascending pharyngeal and maxillary arteries
How does the chorda tympani leave the tympanic cavity
Via the petrotympanic fissue
What does the chorda tympani join
The lingual nerve
What does the chorda tympani provide
Parasympathetic innervation to the sublingual and submandibular salivary glands and special taste to the anterior 2/3rd of the tongue
What does the auditory tube connect
The nasopharynx with the tympanic cavity
What is the lateral section of the auditory tube composed of
A bony canal lined with mucosa
What is the medial section of the auditory tube compose of
Cartilaginous and membranous tubes
What opens the lumen of the auditory tube
The contraction of tensor veli palatini
What does the opening of the auditory tube cause
Equalisation of pressure on both sides of the tympanic membrane
What innervates the auditory tube
Provided sensory innervation via CN XI
What provides blood to the middle ear
Mainly from the anterior tympanic but also from ascending pharyngeal, middle meningeal, posterior auricular, artery of the pytergoid canal and caroticotympanic branch of the internal carotid
What is within the inner ear
Bony and membranous labyrinths
What are membranous labyrinths
A continuous system of ducts and sacs within the bony labyrinth
What are the membranous labyrinths suspended in
Perilymph
What is contained within the membranous labyrinths
Endolymph
Function of endolymph and perilymph
Conduction of sound vibrations and respond to mechanical forces
What are the parts of the semicircular canals
Anterior, posterior and lateral
Arrangement of the parts of the semicircular canals
The anterior and posterior are at 90 degrees and the lateral is horizontal
What is within the semicircular canals
Semicircular ducts
What are the semicircular ducts continuous with
The ampulla
What is the ampulla
A swelling at the end of a duct
What is within the ampulla
The crista ampullaris
Function of the crista ampullaris
Responds to angular movements of the head
What is within the vestibule
The utricle and saccule
What is within the utricle and saccule
Equilibrium receptors known as maculae
Function of the maculae
Respond to the pull of gravity and changes in head position
What supplies the inner ear with blood
Main supply from the internal auditory
What are the branches of the internal auditory artery
Common vestibular and cochlear arteries
What is the internal auditory artery usually a branch of
Anterioinferior cerebellar or the basilar arteries
