Clinical anatomy of the ear Flashcards
what are the 2 parts of the temporal bone?
- squamous part
- petrous part
what makes up the external ear and whats it function?
- auricle to tympanic membrane
- via external acoustic meatus
- collects and conveys sound waves to tympanic membrane
what makes up the middle ear and whats it function?
- tympanic membrane to oval window
- also eustachian tube
- amplifies & conducts sound waves to the internal ear
what makes the internal ear and whats it function?
-oval window to internal acoustic meatus
-converts special sensory information-into fluid waves,
then APs,conducts APs to brain
what is the external ear made of and whats it’s properties?
- temporal bone
- elastic cartilage
- avascular
- nutrients from skin
- do not use anaesthetic containing adrenaline on external ear
what is the ear canal made of?
- 1/3 cratilage
- 2/3 bony and is lined with skin
what is the nerve supply to the auricle?
- C2,3
- CN VII
- CN V3
- CN X (look at lecture side 8)
what lymph nodes drain the auricle?
- Lateral surface of superior half -parotid lymph nodes
- Cranial surface of superior half-mastoid lymph nodes (and deep cervical)
- Rest of auricle, including lobe- superficial cervical lymph nodes
where does the lymph eventually drain to?
deep cervical lymph nodes (in carotid sheath) then into the thoracic duct or right lymphatic duct then into the
venous angle
what is the difference between a child’s EAM and an adults?
- childs is short and straight (gently pull auricle posteroinferiorly)
- adults is curved and gently pull auricle posterosuperiorly
what are the 4 parts of the ear of the otoscopic examination?
- pars flaccida (thin part of the tympanic membrane superiorly)
- the jumbo
- the cone of light
- pars tensa (thick part of the tympanic membrane posteroinferiorly)
what is the general sensory nerve supply to the tympanic membrane?
external surface- mostly CN V3
internal surface- CN IX
where does the glossopahrygeal nerve provide sensory innervation to?
middle ear cavity eustachian tube nasopharynx oropharynx tonsils
what is the function of the Eustachian tube ?
connects middle ear cavity to nasopharynx
what are the 3 auditory ossicles?
- malleus
- incus
- stapes
how do the 3 ossicles articulate to each other?
synovial joints