Theme 8 anatomy Flashcards
what is the function of the external auditory meatus
carries air vibrations from the concha of the external ear to the tympanic membrane
where is the tympanic membrane
at the end of the canal
what nerve passes across the medial aspect of the upper portion of the membrane
chorda tympani
what are the components of the middle ear
tympanic cavity
pharyngotympanic tube
what is contained in the tympanic cavity
air
ossicles
muscles
what are muscles provide a protective action in the tympanic cavity
tensor tympani & stapedius
what is contained in the inner ear
bony labyrinth
- vestibule
- cochlea
membranous labyrinth
what is function of the vestibule
communicate with the other 2 areas of the internal ear and middle ear through vestibular and cochlear windows
what is the function of the cochlea
hearing organ
communicates with the anterior aspect of the vestibule
what are the parts of the temporal bone
squamous zygomatic process tympanic ring styloid process petromastoid process
what is the tympanic ring
tympanic portion present at birth as a ring of bone deficient superiorly
what is the petromastoid part of the temporal bone
thicker, pyramid-shaped portion
what are the foraminae in the temporal bone
jugular foramen carotid canal stylomastoid fo internal auditory meatus greater and lesser petrosal hiatuses
what nerve arises from the internal auditory meatus
vestibulo-cochlear
what nerves do the greater & lesser petrosal hiatuses transmit
greater & lesser petrosal nerve
during which fetal week do the squamous and tympanic portions of the temporal bone begin to develop
eighth
where does the petromastoid portion develop
in cartilage
when do the tympanic, squamous and petromastoid portions unite
during the first year of life
from which brachial arches do the styloid process and the ossicles develop
first 2 brachial arches
what does the middle ear cavity form
the first pharyngeal cleft
where does the tubotympanic recess form
around the first and second arch cartilages
wheres does the tegmen tympani grow
laterally over the end of the tubotympanic recess
where does the tympanic ring form
around the end of the tubotympanic recess
where do the petrous and squamous parts of the temporal bone form
petrous- medially
squamous- laterally
what is the tubotympanic recess
part of first endodermal pharyngeal pouch, develops into the middle ear
what are the boundaries of the middle ear
anterior wall- pharyngotympanic tube
medial wall- fenestra cochleae, fenestra vestibuli, promonotory
posterior- pyramid
lateral wall- tympanic membrane, epitympanic recess
what are the ossicles of the middle ear
malleus
incus
stapes- makes the final connection with the inner ear
what is the fucntion of the muscles attached to the ossicles
protect against loud sounds and modulate the frequency response of the ossicles
what is the action of the tensor tympani
pulls on handle of malleus and pulls tympanic membrane inwards
what is the action of the stapedius muscle
pulls anterior aspect of the foot plate dampening its action to counteract loud, low tone sound
what ossicle does malleus attach to
incus
what ossicle does incus attach to
malleus and stapes
what ossicle does stapes attach to
incus
what happens to the tympanic membrane when there is an increase in air pressure
moves medially
what happens to malleus when there is an increase in air pressure
long process moves medially
head rotates laterally on a p axis in epitympanic recess
(this is also similar for body incus)
what happens to incus when there is an increase in air pressure
body- similar to malleus
long process- moves medially
what happens to stapes when there is an increase in air pressure
the base pushes on the oval window like a banging door
what happens to the fluid in the inner ear when there is an increase in air pressure
bulges out the membrane of the cochlear window below
what is function of ossicles
apply force to the oval window only
act as impedance matching device
reduce bone-conducted sound
explain how pressure is equalised by swallowing when an airline cabin is pressurised
build up of pressure on tympanic membrane.
swallowing contracts salpingpharyngeus which raises the larynx (as its part of palatopharyngeus) and opens the auditory tube, equalising pressure
explain why a child may have dilated pupils and dry mouth if scared of the dentist
stimulation of symp ns which innervated dilator pupil
symp stimulation decreases watery saliva production & mucous rich saliva in produced in smaller volumes
where does the facial nerve arise from
the brainstem
what are the two roots of the facial nerve
large motor root
nervous sensory intermediate root
where do the 2 roots of the facial nerve first enter
internal auditory meatus
at what point does the facial nerve enter the facial canal
at the lateral limit of meatus
where does the facial canal carry the facial nerve
laterally above the vestibule to the medial wall of the middle ear
where do the facial nerve and canal pass when turn abruptly
pass posteriorly deep to the medial wall
what happens to the facial nerve when it reaches the posterior wall of the middle ear
it dives inferiorly and exits the skull
through what fo does the facial nerve exit the skull
stylomastoid foramen
what happens the VII when it leaves the skull
enters the parotid gland
where do the cell bodies of the special sensation taste component lie
geniculate ganglion
where is the geniculate ganglion located
within the bend of the facial nerve within the facial canal
what are the branches of the facial nerve
nerve to stapedius
greater petrosal nerve
chorda tympani
external motor branches
through what fo does the chorda tympani leave the middle ear to enter the infratemporal region
petrotympanic fissure
what nerve does the chorda tympani join in the infratemporal region
lingual
what happens when stapes presses on the fenestra vestibuli
fluid vibrations are transmitted to the scala vestibuli. basilar membrane, hairs of hair cells and fenestra cochlea displaced
where does the greater petrosal nerve arise from
genu (containing geniculate ganglion) of the facial nerve
what nerve does the greater petrosal nerve join
deep petrosal nerve from the sup cervical ganglion
where does the nerve to stapedius arise and what is the route
br of the descending portion of the facial nerve and passes anteriorly to the stapedius muscles within the pyramid
where does the chorda tympani arise and what is the route
arise from the descending part of the facial nerve and passes into the middle ear
which 2 br of VII are given off in the petrous temporal bone and form ps innervation to organs in the face other than the eye
chorda tympani
greater petrosal nerve
what does the chorda tympani innervate
submandibular and sublingual salivary glands
what does the greater petrosal nerve innervate
the nasal and palatine mucosal glands
are the axons that leave the petrous temporal bone pre or post ganglionic
preganglionic
what happens when there is a lesion in the facial canal above the geniculate ganglion
lacrimation, stapedius and taste absent
what happens when there is a lesion between the genicualte ganglion and stapedius nerve
lacrimation present
stapedius and taste absent
what happens when there is lesion between the stapedius nerve and chorda tympani
lacrimation and stapedius present
taste absent
what happens when there is lesion distal to chorda tympani
lacrimation stapedius and taste present
how do you test for lacrimation
litmus paper test
what is the test for stapediud
impedance audiometry
what are the contents of the orbit
the eyeball the extraocular muscles levator palpebrae superioris optic nerve oculomotor nerve trochlear nerve abducent nerve opthalmic divsion of V infraorbital nerve ciliary ganglion lacrimal gland
where does the nasolacrimal duct empty
lacrimal secretions into the inferior meatus
what is the autonomic innervation for the lacrimal gland
ps innervation from greater petrosal br of facial nerve enters pterygopalatine fossa and synapse in pterygopalatine ganglion. post ganglionic axons travel within the zygomatic nerve, enter the orbit and joins lacrimal nerve and pass to the lacrimal gland
what structures are transmitted by the superior orbital fissure
sup and inf oculomotor (III)
trochlear nerve (IV)
abducent nerve (VI)
v1- lacrimal, frontal and nasociliary nerves
what is the common origin for the extraocular muscles (except inferior oblique)
tendinous ring
what is the action and innervation of medial rectus
adduction
III(inferior division)
what is the action and innervation of lateral rectus
abduction
VI
what is the primary and secondary action of superior rectus and its innervation
1- elevation and adduction
2- inward rotation
III (superior division)
what is the primary and secondary action of inferior oblique and its innervation
1-elevation and abduction
2-outward rotation
III
what is the primary and secondary action of inferior rectus and its innervation
1-depression and adduction
2-outward rotation
III
what is the primary and secondary action of superior oblique and its innervation
1-depression and abduction
2- inward rotation
IV
what dos the orbital surface of the frontal bone articulate with
frontal bone
zygomatic process of temporal bone
maxilla
greater wing of sphenoid
what fo are located in the greater wing of sphenoid
fo ovale, spinosum and rotundum
superior oblique innervation
trochlear
lateral rectus innervation
abducent
what nerve is the frontal nerve a branch of
v1- opthalmic division of trigeminal
what does the inferior orbital fissure transmit
opthalmic vein
orbital branch of middle meningeal
what do the anterior and posterior ethmoidal foramina do
transport the anterior and posterior ethmoidal nerves to the ethmoidal air sinuses
what are the attachments of the levator palpebral superioris
roof of orbit and skin of upper eye lid
what muscle opposes the action of LPS
orbicularis oculi
what are the attachments of the superior rectus
tendinous ring to superior aspect of the eyeball
what are the attachments of inferior rectus
tendinous ring to the posterior infero aspect of the eyeball
what are the attachments of lateral rectus
tendinous ring to lateral aspect of eye ball
what are the attachments of the superior oblique
from tendon above the common tendinous ring, passes through trochlear and inserts into superoposterolateral aspect of eyeball
what are the attachments of inferior oblique
arise from the floor of the orbit and inserts into the psoteroinferolateral aspect of they eyeball
what are the 3 terminal br of the opthalmic divison of the trigeminal nerve
lacrimal nerve
frontal nerve
nasociliary nerve
what does the lacrimal nerve do
passes to the lateral wall of the orbit towards the lacrimal gland
from which nerve does the lacrimal receive branches from
zygomatic nerve (br of V2)
what does the lacrimal nerve pick up and deliver to the lacrimal gland
picks up hitchhiking post synaptic secretory fibres from the pterygopalatine ganglion and takes them to the lacrimal gland
what else does the lacrimal nerve supply
sensation to the lateral aspect of the upper lip
what does the frontal nerve divide into
supraorbital and supratrochlear
where does the frontal nerve pass
out of orbit to supply skin and conjunctiva of the upper lid and skin of the forehead and scalp
how does the nasociliary nerve pass
anteromediallly
what are the 3 collateral br of the nasociliary nerve
ganglionic branches
long ciliary nerves
posterior ethmoidal nerve
external nasal nerve
what are the 2 terminal branches of the nasociliary nerve
anterior ethmoidal nerve
infratrochlear nerve
what does the anterior ethmoidal nerve do
supplies the anterior ethmoidal cells and skin on the external nose as the external nasal nerve
where does the ciliary ganglio receive sensory fibres frm
cornea and iris via nasociliary nerve
what is the sympathetic root for the ciliary ganglion
arises from the internal carotid and opthalmic artery plexus and supplies the dilator pupilale muscle
what is the ps root of ciliary ganglion
from CNIII which is motor to sphincter pupillae and ciliary muscles
what are the br of distribution of the ciliary ganglion
short ciliary nerves
what are the 3 coats of the eyeball
fibrous
vascular
neural
what does the fibrous coat consist of
sclera and cornea
what does the vascular coat consist of
choroid, ciliary body and iris
what does the neural coat consist of
retina
what are the muscles found in the iris
constrictor pupillae and dilator pupillae
what is the innervation of the constictor pupillae
ps fibres of III from ciliary ganglion
what is the innervation of dilator pupillae
sympathetic fibres
what does the neural coat consist of
nervous layer -macula
what is the lacrimal gland
a serous gland wrapped around the free border of the LPS muscle
how to tears wash over the eyelid and then where do they go
into lacrimal sac then nasolacrimal duct to inferior meatus
where does the parasympathetic supply to the lacrimal gland come from
from pterygopalatine ganglion the greater petrosal nerve and deep petrosal nerve fuse to form the nerve of the pterygoid canal. post ganglionic fibres enter the orbit through the inferior orbital fissure and hitchhike with the lacrimal nerve to the lacrimal gland
where does the zygomatic nerve pass
through the inferior orbital fissure
what nerves are transmitted by the internal auditory meatus
CNVII and CNVIII
