Saturday, November 28, 2020

External Ear

 The external ear consists of:

. The auricle or pinna.
. The external acoustic meatus. 







AURICLE/PINNA 

The auricle is the part seen on the surface, The greater part of it is made up of a single crumpled plate of elastic cartilage which is lined on both sides by skin. 

However, the lowest part of the auricle is soft and consists only of fibrofatty tissue covered by skin
This part is called the lobule. 

The rest of the auricle is divided into four parts These are helix, antihelix, concha, tragus, scaphoid fossa 

the large depression called the concha; it leads into the external acoustic meatus.
In relation to the auricle, there are a number of muscles. These are all vestigial in man. 

In lower animals, the intrinsic muscles alter the shape of the auricle, while the extrinsic muscles move the auricle as a whole. 






Nerve Supply 

The upper two-thirds of the lateral surface of the auricle are supplied by the auriculotemporal nerve;
the lower one-third by the great auricular nerve 

The upper two-thirds of the medial surface are supplied by the lesser occipital nerve; 

the lower one-third by the great auricular nerve.
The root of the auricle is supplied by the auricular branch of the vagus 

The auricular muscles are supplied through branches of the facial nerve. 



BIood Supply 


The blood supply of the auricle is derived from the posterior auricular and superficial temporal arteries


The lymphatics drain into the preauricular, and postauricular lymph nodes. 





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