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Outer ear | |
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Details | |
Identifiers | |
Latin | auris externa |
MeSH | D004431 |
NeuroLex ID | birnlex_1705 |
TA98 | A15.3.01.001 |
TA2 | 6862 |
FMA | 52781 |
Anatomical terminology |
This article is one of a series documenting the anatomy of the |
Human ear |
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The outer ear, external ear, or auris externa is the external part of the ear, which consists of the auricle (also pinna) and the ear canal. [1] It gathers sound energy and focuses it on the eardrum (tympanic membrane).
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.[ citation needed ]
Intrinsic muscles of external ear | |
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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 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 | |
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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:
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]
This section needs expansion. You can help by adding to it. (December 2013) |
One consequence of the configuration of the outer ear is selectively to boost the sound pressure 30- to 100-fold for frequencies around 3 kHz. This amplification makes humans most sensitive to frequencies in this range—and also explains why they are particularly prone to acoustical injury and hearing loss near this frequency. Most human speech sounds are also distributed in the bandwidth around 3 kHz. [6]
Malformations of the external ear can be a consequence of hereditary disease, or exposure to environmental factors such as radiation, infection. Such defects include:
Usually, malformations are treated with surgery, although artificial prostheses are also sometimes used. [9]
If malformations are accompanied by hearing loss amenable to correction, then the early use of hearing aids may prevent complete hearing loss. [17]
Anotia describes a rare congenital deformity that involves the complete absence of the pinna, the outer projected portion of the ear, and narrowing or absence of the ear canal. This contrasts with microtia, in which a small part of the pinna is present. Anotia and microtia may occur unilaterally or bilaterally. This deformity results in conductive hearing loss, deafness.
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue. The nerve typically travels from the pons through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen. It arises from the brainstem from an area posterior to the cranial nerve VI and anterior to cranial nerve VIII.
Articles related to anatomy include:
An ear is the organ that enables hearing and body balance using the vestibular system. In mammals, the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.
The auricle or auricula is the visible part of the ear that is outside the head. It is also called the pinna, a term that is used more in zoology.
Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss, it is referred to as a mixed hearing loss. Depending upon the severity and nature of the conductive loss, this type of hearing impairment can often be treated with surgical intervention or pharmaceuticals to partially or, in some cases, fully restore hearing acuity to within normal range. However, cases of permanent or chronic conductive hearing loss may require other treatment modalities such as hearing aid devices to improve detection of sound and speech perception.
Otoplasty is a procedure for correcting the deformities and defects of the pinna, whether these defects are congenital conditions or caused by trauma. Otoplastic surgeons may reshape, move, or augment the cartilaginous support framework of the pinna to correct these defects.
The ear canal is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about 2.5 centimetres (1 in) in length and 0.7 centimetres (0.3 in) in diameter.
The auriculotemporal nerve is a sensory branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to parts of the external ear, scalp, and temporomandibular joint. The nerve also conveys post-ganglionic parasympathetic fibres from the otic ganglion to the parotid gland.
Microtia is a congenital deformity where the auricle is underdeveloped. A completely undeveloped pinna is referred to as anotia. Because microtia and anotia have the same origin, it can be referred to as microtia-anotia. Microtia can be unilateral or bilateral. Microtia occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It may occur as a complication of taking Accutane (isotretinoin) during pregnancy.
The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound.
Hearing loss with craniofacial syndromes is a common occurrence. Many of these multianomaly disorders involve structural malformations of the outer or middle ear, making a significant hearing loss highly likely.
The antitragicus is an intrinsic muscle of the outer ear.
The transverse muscle of auricle is an intrinsic muscle of the outer ear.
The Helicis minor is a small skeletal muscle. The helicis minor is an intrinsic muscle of the outer ear. The muscle runs obliques and covers the helical crus, part of the helix located just above the tragus.
The anterior auricular branches of the superficial temporal artery are distributed to the anterior portion of the auricula, the lobule, and part of the external meatus, anastomosing with the posterior auricular. They supply the external acoustic meatus and the visible part of the ear.
The following outline is provided as an overview of and topical guide to human anatomy:
The posterior auricular muscle is a muscle behind the auricle of the outer ear. It arises from the mastoid part of the temporal bone, and inserts into the lower part of the cranial surface of the auricle of the outer ear. It draws the auricle backwards, usually a very slight effect.
The superior auricular muscle is a muscle above the auricle of the outer ear. It originates from the epicranial aponeurosis, and inserts into the upper part of the medial surface of the auricle. It draws the auricle upwards.
The anterior auricular muscle, the smallest of the three auricular muscles, is thin and fan-shaped, and its fibers are pale and indistinct. It arises from the lateral edge of the epicranial aponeurosis, and its fibers converge to be inserted into a projection on the front of the helix.
This article incorporates text in the public domain from page 1033 of the 20th edition of Gray's Anatomy (1918)
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