Middle & Inner Ear Flashcards
Eustachian tube divided into
Bony part ~ 1.2 cm
Cartilaginous part ~ 2.4 cm
Narrowest part of Auditory tube
Isthmus
Function of Eustachian tube
To equalise the pressure on both side of Tympanic Membrane
Muscle responsible for opening of Eustachian tube
Tensor Veli Palatini Muscle
Assisted by Levator Veli Palatini Muscle
Tensor Veli Palatini is also know as
Dilator Tubae Muscle
Lateral Wall of Middle Ear ~
Derived from ~
Tympanic Membrane
Derived From 1st Pharyngeal Membrane
Made up of all the 3 germ layers
Roof of Middle Ear is Formed By ___________
And is separating Middle Ear from _______
Tegmen tympani ~ thin plate of bone
Separates Middle Ear from Middle Cranial Fossa
Floor (Bony plate) of Middle ear is separating from
Floor is pierced by
Internal Jugular Vein
Pierced by Tympanic branch of Glossopharyngeal ~ in turn forms Tympanic Plexus
Lower part of anterior wall of Middle ear cavity is relating to
Inter Carotid Artery
Upper Part of Anterior wall of Middle Ear Cavity has
2 Bony Canals
1st for Tensor Tympani Muscle
2nd for Auditory Tube
Aditus is present in which wall of middle ear cavity
Posterior Wall
Through Aditus Middle ear is communicating with Mastoid Antrum
Pyramidal Eminence contains
Stapedial Muscle
Structures in Posterior Wall of Middle Ear
Aditus
Pyramidal eminence
Bony canal for Facial Nerve
Promontory in the medial wall of middle ear is due to
Basal Turn of Cochlea
Tympanic plexus is formed by
Is present over _________
Tympanic branch of IX
+
Caroticotympanic Branch (sympathetic plexus over ICA)
Oval window also known as
Fenestra Vestibuli
Fenestra Vestibuli is closed by
Foot plate of Stapes
Fenestra Cochlea is closed by
Fenestra Cochlea / Round Window
Is closed by Secondary Tympanic Membrane
Perilymph is derived from
CSF
Endolymph is secreted by
Stria Vascularis of Cochlear Duct
List Bony Labyrinth consists of
Cochlea
Vestibule
Semicircular canals
Membranous labyrinth present in
Cochlea ~
Semicircular Canals ~
Ventricle ~
Cochlear Duct
Semicircular Duct
Utricle and Saccule
Centre part of cochlea is called
Modiolous
The cochlear canal making 2.5-2.75 turns around the Modiolous
Osseus spiral lamina coming from the Modiolous ~
extending into the cochlear canal
And divides cochlear canal into
3 Parts;
Scala vestbuli
Scala tympani
Scala media (cochlear duct / membranous labyrinth)
Boundaries for Scala Media
Above ~ Vestibular Membrane
Below ~ Basilar Membrane
At the Apex of Modiolous, the Scala Vestibuli and Scala Tympani communicating with each other is called
Helicotrema
Perilymph is communicating with the CSF through
Aqueduct of Cochlea
Inner ear infection is spreading to CNS through which opening
Aqueduct of Cochlea
Aqueduct of Vestibuli transmit the
Endolymphatic Duct
Sensory epithelium present in the cochlear duct for hearing is
Organ of Corti
Peripheral fibres of Spiral Ganglion is innervating the
Inner and Outer Hair Cells in Organ of Corti
Majority of Peripheral fibres of Spiral Ganglion is innervating the
Inner Hair Cell > Outer Hair Cell
Central processes of Spiral Ganglion will form
Cochlear Nerve
Describe Auditory Pathway
E
C
O
L
I
M
A
E ~ Eighth nerve
C ~ Cochlear nucleus
O ~ sup. Olivary nucleus
L ~ Lateral Leminiscus
I ~ Inferior colliculus
M ~ Medial geniculate body
A ~ Auditory cortex (ant. part of superior temporal gyrus)
Semicircular canals opens into vestibule by means of
5 Openings
Semicircular duct opens into the Utricle by means of 5 openings
Cochlear duct opening into the Saccule by means of
Ductus Reunions
Utricle and Saccule joining together and forms
Utriculo-Sacculo Duct
Which continue as Endolymphatic Duct
Endolymphatic duct is passing through Aqueduct of Vestibuli
Dilation in Endolymphatic Duct is forming
Endolymphatic Sac ~ observed between the 2 layers of dura
Sensory epithelium present in the Saccule and Utricle is called
Maculae
For Static Balance
Number of Semicircular Canals
3 ~ Anterior, Posterior and Lateral
Anterior and Posterior ~ in vertical axis
Lateral ~ in horizontal axis
________________ canal is Perpendicular to Long Axis of Petrous Temporal Bone
Anterior Semicircular Canal
Posterior Semicircular Canal is ___________ to Long Axis of Petrous Temporal Bone
Parallel
Angle between each semicircular canal is
90 Degree
The dilated end of semicircular canal is
Ampulla
Each semicircular canal has dilated end and normal end
What is Crus Commune
One end of anterior semicircular canal joins with one end of posterior semicircular canal
Due to which semicircular canals opens into vestibule by means of only 5 openings
Sensory Epithelium in the Semicircular Duct(canal) is called
Crista ~ for Kinetic Balance
