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.
No comments:
Post a Comment