ear cavity Flashcards
ear
receptor organ for hearing and equilibrium
what are the 3 main regions of the ear
- external ear: functions in hearing, transference of sound to ear
- middle ear: hearing, connects to nasal cavity
- internal ear: participates in hearing and equilibrium
describe the components of the external ear
-auricle: elastic cartilage: gathers and directs sound waves to external acoustic meatus
-external acoustic meatus short cannal running medially from the auricle to the tympanic membrane (eardrum) and conducting sound waves
-tympanic membrane: forms the boundary between the external ear and the middle ears. eardrum
– covered with thin skin internally and a mucous membrane of the middle ear
– moves in response to air vibrations
– movements transmit to auditory ossicles
innervation of the ear
-auriculotemporal nerve V3
-small area: CN X
-internal ear: CN IX vestibulocochlear nerve
middle ear
-describe the tympanic membrane
narrow, filled with air, lines by a mucous membrane
-location: petrous portion of temporal bone
-2 parts:
tympanic cavity proper: directly internal to the tympanic membrane
epitympanic recess: superior to the membrane
middle ear:
the tympanic membrane connects with the nasopharynx by:
pharyngotympanic tube (anteromedially)
-and posteriorly with the mastoid antrum
middle ear internal ear ossicles
-malleus, incus, and scapes
middle ear muscles
muscles, innervation, and function
-dampen or resist movements of the ossicles
-strapedius: origin from the wall of ear to stapes
-tensor tympani muscle: from wall of ear and inserts to malleus and tempanic membrane
-innervation: chorda tympani nerve (branch VII) plexus
pharyngotympanic tube
connects the tympanic cavity to the nasopharynx where it opens posterior to the inferior nasal meatus
-structure: posterolateral 1/3 is bony, the rest is cartilaginous, lined with a mucous membrane
-function: equalize pressure in the middle ear with atm to allow free movement of tympanic membrane
inner ear contains
vestibulocochlear organ: sound reception and balance
vestibulocochlear nerve
-passes through the internal acoustic meatus and divides near the lateral end of the meatus
-cochlear nerve: hearing
-vestibular nerve: equilibrium
sound transmission
1. sound waves enter through the
external ear and vibrate the tympanic membrane
sound transmission
2. vibrations are transmitted through
ossicles of the middle ear
sound transmission
3. base of stapes:
vibrates in the oral window (between stapes and cochlea), which transmits amplified energy to the fluids of the cochlea
sound transmision
4. vibration from the stapes are transmitted through:
the perilymph chamber to the cochlear duct where the hair cells of the cochlear nerve are transmitted
sound transmission
5. vibrations are dissipated back:
into the middle ear cavity at the round window, releasing their remaining energy into the air of the tympanic cavity
ear innervation
-motor
-Trigeminal V3: tensor tympani muscle
-facial nerve VII: skin stapedius muscle
ear innervation
general sensory:
-trigeminal V3: skin of external ear
-facial nerve VII: skin of external ear
-glossopharyngeal nerve IX: mucosa of the tympanic cavity, pharyngotympanic tube, and internal surface of tympanic membrane
-vagus nerve X: skin posterior to the ear and external acoustic meatus
ear innervation
-special sense
-vestibulocochlear nerve VIII: hearing and equilibrium
vertebral arteries
supply:
branches:
origin:
converge:
-supply: posterior brain
-branches: subclavian artery
-origin: arch of aorta
converge: basilar artery (base of brain), and posterior cerebral artery (posterior cerebrum)
arteries of head and neck
most common:
end and divides:
common carotid arteries
ends and divides: branch under the maxilla
branches of common carotid artery
-external carotid artery: supply most structures external to the cranium by sending multiple branches to target organs
internal carotid artery: no branches in the neck, supply the orbits and most of the brain- front
internal carotid artery
-paired arterial branches of the common carotid artery
-supplies: orbits and most of the cerebrum
-anterior cerebral arteries
-middle cerebral arteries
-opthalmic arteries
external carotid artery branches
-superior thyroid
-lingual
-facial
-occipital
-posterior auricular
-ascending pharyngeal
-superficial temporal
-maxillary
external carotid artery branches
maxillary branch and divisions
-to internal neurocranium, masticatory muscles, and nasal cavity
-divisions:
-lower teeth
-upper teeth
-superior oral cavity (middle meningeal artery): enters foramen spinosum and is on the surface of the dura mater
carotid body and carotid sinus location and innervation
at the bifurcation of the common carotid artery into internal and external branches
innerv: glossopharyngeal nerve CN IX
carotid body
mass of tissue with chemoreceptors: that monitor oxygen and carbon dioxide levels
carotid sinus
area in the wall of the artery with baroreceptors, monitor blood pressure
- internal jugular vein
drain almost all of the blood via dural sinuses, anterior face, cervical viscera, and deep muscles of the neck
- external jugular vein
drain parts of the scalp and face
the internal and external jugular vein join before the
subclavian vein
carotid sheath
wraps jugular vein and carotid artery
-protective CT
dural sinuses
drain the brain between two layers of dura mater
what are the two layers of dura mater
-periosteal: closest to bone
-meningeal: brain
blood drains to what part of the vein:
exit:
posterior brain
exit: internal jugular vein at jugular foramen
covernus sinus
lateral to sella turcica, receives blood from opthalmic veins
-innervatin: internal carotid, carotid plexus, III, IV, V1, V2 and VI
cranial meninges
protect brain, form arteries, vains, and sinuses, enclose subarachnoid space with CSF
1. dura mater
2. arachnoid mater
3. pia mater 4
extradural hemmorage:
blood torn from branches of middle meningal artery, on the outside of dura mater
dura border hematoma:
breakage of vein, creates a space at dura-arachnoid junction, results from a blow to head
subarachnoid hemmorage:
breakage of vein, into the subarachnoid space
-results from a ruptured aneurysm and head trauma
