Ears - Anatomy and Physiology Flashcards
Into what three parts can the ear be divided?
External
Middle
Inner
What are the 2 functional/structural differing sections of the external ear?
The auricle (or pinna) The external auditory meatus.
What is the auricle/pinna? What is its function?
The auricle is essentially the external, visible ear.
Its function is to capture and transmit sound to the external acoustic meatus.
What is the outer curvature of the ear called?
Helix
What is the name of the curved elevation within the outer curve? What does this divide superiorly to form?
This is the antihelix. It divides to form into 2 cura - the inferoanterior crus and the superoposterior crus.
What is the name of the hollow depression within the middle of the visible ear? What does this continue to??
Concha of Auricle
This is continuous with the external auditory meatus.
What is the function of the concha of the ear?
Acts to direct sound into the external auditory meatus.
Name the slight lips either side of the opening of the external auditory meatus?
Tragus
Antitragus
Generally outline the vasculature of the external portion of the ear.
The main vessels involved are the posterior auricular, superficial temporal and occipital arteries and veins.
Generally outline the innervation of the external portion of the ear.
Cutaneous innervation to the skin of the auricle comes from the greater auricular, lesser occipital and branches of the facial and vagus nerves.
Generally outline the lymphatic drainage of the auricle (pinna)?
Lymphatic drainage of the auricle is to the preauricular, posterior auricular and superficial temporal lymph nodes.
What is the external auditory meatus?
Tube that extends from the deep part of the concha to the tympanic membrane.
What are the walls of the external auditory meatus given their structure by?
Cartilage from the auricle, and bony support from the temporal bone.
In terms of the External Auditory Meatus outline:
- Vasculature
- Innervation
- Lymphatic Drainage?
V
- External part of meatus superficial temporal and posterior auricular.
- Internal part - deep auricular branch of maxillary artery
I
Mandibular and Vagus Nerve
L - Pre and Post auricle and cervical chain
What is the tympanic membrane?
“Ear Drum”
How many layers does the tympanic membrane have?
What are these?
3 layers
- Outer layer - continuous with skin of EAC
- Middle fibrous layer
- Inner layer of resp. epithelium
What is the respiratory layer of the tympanic membrane?
ciliated columnar epithelium with goblet cells
What is otitis media?
An infection of the middle ear which causes pus and fluid to build up. This causes an increase in pressure, and eventually the eardrum ruptures.
What are the causes of eardrum perforation?
Infection
Trauma
Usually will heal itself but if very bad surgery can be indicated.
Where does the middle ear lie?
Middle ear lies within the temporal bone, extends from the tympanic membrane to the lateral wall of the ear.
What is the main function of the middle ear? And how does it do this?
The main function of the middle ear is to transmit vibrations from the tympanic membrane to the inner ear – it does this via the three bones of the ear.
What is the “roof” of the middle ear?
Thin bone from the petrous part of the temporal bone.
What is the “floor” of the middle ear?
(known as the jugular wall)
Thin layer of bone separating meddle ear from Internal Jugular
What is the “lateral wall” of the middle ear?
Tympanic membrane
What is the “medial wall” of the middle ear?
Formed by the lateral wall of the internal ear.
What is the “anterior wall” of the middle ear?
The anterior wall is a thin bony plate with two openings; for the auditory tube and the tensor tympani muscle. It separates the middle ear from the internal carotid artery.