ANAT 2626 Chapter 7 - Ear (Mercy Navis)

ANAT 2626 Chapter 7 - Ear (Mercy Navis) - 1 Chapter 7 Pages...

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1 Chapter # 7 - Pages 966 to 980 Ear is the vestibulocochlear organ, has two functions 1. equilibrium ( internal ear ) 2. hearing ( external and middle ear ) Ear consists of three parts 1. external ear 2. middle ear 3. internal ear External ear 1. concerned with the transference of sound to the internal ear 2. composed of the shell - like auricle ( pinna ) which collects the sound 3. external auditory meatus ( canal ) which conducts sound to the tympanic membrane Auricle 1. composed of an irregularly shaped plate of elastic cartilage, that is covered by thin skin 2. the deepest depression of the auricle is the concha 3. the elevated margin of the auricle is the helix 4. the lobule ( lobe ) is non - cartilaginous, consists of Fbrous tissue, fat and blood vessels 5. tragus is a tongue - like projection overlapping the opening of the external acoustic meatus Arterial supply to the auricle 1. posterior auricular artery, is a branch of external carotid artery 2. superFcial temporal artery, is a branch of external carotid artery Nerve supply to the skin of the auricle 1. great auricular nerve, comes from the ventral rami of C2, C3 2. auriculotemporal nerve, is a branch of mandibular nerve External acoustic meatus 1. is a canal that leads inward from the auricle to the tympanic membrane 2. it is 2 - 3 cm long in adults 3. its lateral one - third is cartilaginous and lined with skin 4. its medial two - thirds is bony and lined with skin 5 the cartilaginous part contains ceruminous and sebaceous glands in the subcutaneous tissue 6. they produce cerumen ( earwax ) Tympanic membrane 1. separates the external ear from the middle ear or tympanic cavity 2. it is a thin, oval, semitransparent membrane at the medial end of the external acoustic meatus 3. it forms a partition between the meatus of the external ear and the tympanic cavity of the middle ear 4. external it is covered by skin and internally by the mucous membrane 5. the peak of the concavity of the membrane is the umbo 6. the handle of malleus attaches to the inner surface of the membrane 7. the superior thin part of the membrane is called pars Faccida 8. the remaining part of the membrane is called pars tensa ±unction of the tympanic membrane 1. it moves in response to air vibrations that pass to it through the external acoustic
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2 meatus 2. movements of the membrane are transmitted by the auditory ossicles through the middle ear to the internal ear Nerve supply of the tympanic membrane 1. auriculotemporal nerve ( branch of mandibular nerve ) supplies the external surface 2. auricular branch of vagus ( 10 th cranial nerve ) supplies the external surface 3. glossopharyngeal nerve ( 9 th cranial nerve ) supplies the internal surface Middle ear ( tympanic cavity ) 1. concerned with the transference of sound to the internal ear 2. it is a narrow air - Flled chamber, in the petrous part of the temporal bone 3. it has two parts a) tympanic cavity proper, the space directly internal to tympanic membrane b)
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This note was uploaded on 11/22/2011 for the course ANAT 2626 taught by Professor Ronaldg.mayne during the Winter '11 term at Life Chiropractic College West.

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ANAT 2626 Chapter 7 - Ear (Mercy Navis) - 1 Chapter 7 Pages...

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