Outer ear

The visible part is called the auricle, also known as the pinna, especially in other animals. It is composed of a thin plate of yellow elastic cartilage, covered with integument, and connected to the surrounding parts by ligaments and muscles; and to the commencement of the ear canal by fibrous tissue. Many mammals can move the pinna (with the auriculares muscles) in order to focus their hearing in a certain direction in much the same way that they can turn their eyes. Most humans do not have this ability.[2]

From the pinna, the sound waves move into the ear canal (also known as the external acoustic meatus) a simple tube running through to the middle ear. This tube leads inward from the bottom of the auricula and conducts the vibrations to the tympanic cavity and amplifies frequencies in the range 3 kHz to 12 kHz.

Intrinsic muscles of external ear
The muscles of the auricula
Details
Nerve	Facial nerve
Actions	Undeveloped in humans
Identifiers
MeSH	D004431
NeuroLex ID	birnlex_1705
TA98	A15.3.01.001
TA2	6862
FMA	52781
Anatomical terms of muscle

The intrinsic auricular muscles are:

• The helicis major is a narrow vertical band situated upon the anterior margin of the helix. It arises below, from the spina helicis, and is inserted into the anterior border of the helix, just where it is about to curve backward.
• The helicis minor is an oblique fasciculus, covering the crus helicis.
• The tragicus is a short, flattened vertical band on the lateral surface of the tragus. Also known as the mini lobe.
• The antitragicus arises from the outer part of the antitragus, and is inserted into the cauda helicis and antihelix.
• The transverse muscle is placed on the cranial surface of the pinna. It consists of scattered fibers, partly tendinous and partly muscular, extending from the eminentia conchae to the prominence corresponding with the scapha.
• The oblique muscle also on the cranial surface, consists of a few fibers extending from the upper and back part of the concha to the convexity immediately above it.

The intrinsic muscles contribute to the topography of the auricle, while also function as a sphincter of the external auditory meatus. It has been suggested that during prenatal development in the womb, these muscles exert forces on the cartilage which in turn affects the shaping of the ear.[3]

Auricular muscles
The muscles of the pinna
Auricular muscles in context with the other facial muscles
Details
Origin	Galeal aponeurosis
Insertion	Front of the helix, cranial surface of the pinna
Artery	Posterior auricular artery
Nerve	Facial nerve
Actions	Subtle auricle movements (forwards, backwards and upwards)
Identifiers
Latin	Musculi auriculares
MeSH	D004431
NeuroLex ID	birnlex_1705
TA98	A15.3.01.001
TA2	6862
FMA	52781
Anatomical terms of muscle

The extrinsic auricular muscles are the three muscles surrounding the auricula or outer ear:

• anterior auricular muscle
• superior auricular muscle
• posterior auricular muscle

The superior muscle is the largest of the three, followed by the posterior and the anterior.

In some mammals these muscles can adjust the direction of the pinna. In humans these muscles possess very little action. The auricularis anterior draws the auricula forward and upward, the auricularis superior slightly raises it, and the auricularis posterior draws it backward. The superior auricular muscle also acts as a stabilizer of the occipitofrontalis muscle and as a weak brow lifter.[4] The presence of auriculomotor activity in the posterior auricular muscle causes the muscle to contract and cause the pinna to be pulled backwards and flatten when exposed to sudden, surprising sounds.[5]

Usually, malformations are treated with surgery, although artificial prostheses are also sometimes used.[9]

• Preauricular fistulas are generally not treated unless chronically inflamed.[9]
• Cosmetic defects without functional impairment are generally repaired after ages 6–7.[17]

If malformations are accompanied by hearing loss amenable to correction, then the early use of hearing aids may prevent complete hearing loss.[17]