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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.
Amplification of sound by the pinna, tympanic membrane and middle ear causes an increase in level of about 10 to 15 dB in a frequency range of 1.5 kHz to 7 kHz. This amplification is an important factor in inner ear trauma resulting from elevated sound levels .
Sound is the perceptual result of mechanical vibrations traveling through a medium such as air or water. Through the mechanisms of compression and rarefaction, sound waves travel through the air, bounce off the pinna and concha of the exterior ear, and enter the ear canal.
There are two types of hair cells specific to the auditory system; inner and outer hair cells. Inner hair cells are the mechanoreceptors for hearing: they transduce the vibration of sound into electrical activity in nerve fibers, which is transmitted to the brain. Outer hair cells are a motor structure.
In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the auricle and the ear canal . Since the outer ear is the only visible portion of the ear, the word "ear" often refers to the external part (auricle) alone. [ 1 ]
The transverse muscle of auricle (transverse auricular muscle, [1] transversus auriculae, transversus auricularis or transverse muscle of pinna [2]) is an intrinsic muscle of the outer ear. The muscle is located on the cranial surface of the pinna .
Cross-section through the spiral organ of Corti at greater magnification, showing position of the hair cells on the basement membrane. The organ of Corti is located in the scala media of the cochlea of the inner ear between the vestibular duct and the tympanic duct and is composed of mechanosensory cells, known as hair cells. [2]
Perichondritis is inflammation of the perichondrium, a layer of connective tissue which surrounds cartilage. [2] A common form, auricular perichondritis (perichondritis auriculae) involves infection of the pinna due to infection of traumatic or surgical wound or the spread of inflammation into depth (e.g. Infected transcartilaginous ear piercings).