Earlobe | |
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Details | |
System | Auditory system |
Identifiers | |
Latin | lobulus auriculae (singular), lobuli auricularum (plural) |
TA98 | A15.3.01.003 |
TA2 | 105 |
FMA | 60984 |
Anatomical terminology |
The human earlobe (lobulus auriculae), the lower portion of the outer ear, is composed of tough areolar and adipose connective tissues, lacking the firmness and elasticity of the rest of the auricle (the external structure of the ear). In some cases the lower lobe is connected to the side of the face. Since the earlobe does not contain cartilage [1] it has a large blood supply and may help to warm the ears and maintain balance. However, earlobes are not generally considered to have any major biological function. [2] The earlobe contains many nerve endings, and for some people is an erogenous zone.
The zoologist Desmond Morris in his book The Naked Ape (1967) conjectured that the lobes developed as an additional erogenous zone to facilitate the extended sexuality necessary in the evolution of human monogamous pair bonding. [3]
The earlobe, as a body part built of epithelium and connective tissue, might appear to be derived from dermatome. [4] But this is not the case, as in the surrounding tissue there are no somites and thus no dermatome. In this area, the dermis is derived from cells of mesenchymal cells: the mesenchyme is derived from the sclerotome and splanchnopleura located in the nearby regions of the torso. [5]
The earlobe as a body part arises and develops in the vicinity of auricular follicle, as a result of cascade induction: [6]
Earlobes average about 2 centimeters long, and elongate slightly with age. [7] Although the "free" vs. "attached" appearance of earlobes is often presented as an example of a simple "one gene – two alleles" Mendelian trait in humans, earlobes do not all fall neatly into either category; there is a continuous range from one extreme to the other, suggesting the influence of several genes. [8] [9] [10]
Population | N | Recessive gene frequency (for attached ear lobes) | Source |
---|---|---|---|
Africans | ? | 0.60 | Messeri (1976) [11] |
Afroamericans | 242 | 0.56 | Glass et al. (1952) [12] |
Ainu | ? | 0.49 | Messeri (1967) [11] |
Babinga | ? | 0.87 | Messeri (1967) [11] |
Bavaria | ? | 0.84 | Messeri (1967) [11] |
Bosnia and Herzegovina | 7,325 | 0.55 | Hadžiselimović (1981) [13] |
Brazil | ? | 0.34 | Saldanha (1960) [14] |
Cameroon | ? | 0.83 | Messeri (1967) [11] |
Canadian Aboriginals | 532 | 0.68 | Chaison (1963) [15] |
China | ? | 0.62 | Messeri (1967) [11] |
Hong Kong | 70 | 0.80 | Lai, Walsh (1966) [16] |
India: Bengal | 100 | 0.49 | Dutta (1963) [17] |
Japan | 70 | 0.82 | Lai, Walsh (1966) [16] |
Laponia | ? | 0.71 | Messeri (1967) [11] |
Micronesia | ? | 0.52 | Messeri (1967) [11] |
Nepal | 169 | 0.66 | Bhasin (1969) [18] |
New Guinea | 399 | 0.80 | Lai, Walsh (1966) [16] |
Nicobar | 813 | 0.81 | Gabel (1958) [19] |
Papuans | ? | 0.54 | Messeri (1967) [11] |
Polynesia | ? | 0.39 | Messeri (1967) [11] |
Russia | ? | 0.59 | Messeri (1967) [11] |
Sardinia | 403 | 0.53 | Messeri (1967) [11] |
Scotland | 500 | 0.48 | Chattopadhyay (1968) [20] |
Somalia | ? | 0.42 | Messeri (1967) [11] |
Sweden | 247 | 0.59 | Wiener (1937) [21] |
Tibet | ? | 0.68 | Tiwari, Bhasin (1969) [22] |
United States: Baltimore | 380 | 0.63 | Glass et al. (1952) [12] |
United States: Brooklyn | 248 | 0.92 | Wiener (1937) [21] |
United States: Buffalo | 381 | 0.43 | Dronamraju (1966) [23] |
United States: Pennsylvania | 241 | 0.50 | Glass et al. (1952) [12] |
Earlobes are normally smooth, but occasionally exhibit creases. Creased earlobes are sometimes associated with genetic disorders in children, including Beckwith-Wiedemann syndrome. [24] In some early studies, earlobe creases were thought to be associated with an increased risk of heart attack and coronary heart disease. But more recent studies have concluded that, since earlobes become more creased with age, and older people are more likely to have heart disease than younger people, age rather than intrinsic factors may account for the findings linking heart attack to earlobe creases. [24] The earlobe crease is also called Frank's Sign.
Piercing the earlobes is a commonplace activity in many cultures in many historical eras; no other location on the body is as commonly pierced. Consequently, injury to the earlobe due to the weight of heavy earrings is also common. [25] Some cultures practice earlobe stretching for decorative effects, using piercing ornaments to stretch and enlarge the earlobes to accommodate plugs.
Some research has found that the most frequent complications connected with wearing earrings are: [26]
A noticeable relationship has been found by Polish scientists between the piercing of young girls' earlobes and their subsequently developing allergic skin reactions. [27] [28] [29] In the view of Professor Ewa Czarnobilska, the manager of the research team, the primary reason for the allergies connected to earrings is the presence of nickel, which is a common component of the alloys used in jewelry production and leaches from the earrings. [28] [29] The symptom seen is generally eczema, and is often misdiagnosed as a food allergy, for instance to milk. The specific mechanism in allergies caused by earrings is the contact of nickel ions with the lymphatic system. [28] [29]
The study noted that children who stopped wearing earrings did not see the disappearance of the allergic symptoms. The immune system remembers the presence of the nickel ions in the person's blood and lymph, so the child can still react to: [28] [29]
Research by allergists has found that in a sample of 428 pupils of ages 7–8 and 16–17 years old: [28] [29]
An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies.
An earring is a piece of jewelry attached to the ear via a piercing in the earlobe or another external part of the ear, or, less often, by some other means. Earrings have been worn in diverse civilizations and historic periods, often carrying a cultural significance.
Basophils are a type of white blood cell. Basophils are the least common type of granulocyte, representing about 0.5% to 1% of circulating white blood cells. They are the largest type of granulocyte. They are responsible for inflammatory reactions during immune response, as well as in the formation of acute and chronic allergic diseases, including anaphylaxis, asthma, atopic dermatitis and hay fever. They also produce compounds that coordinate immune responses, including histamine and serotonin that induce inflammation, and heparin that prevents blood clotting, although there are less than that found in mast cell granules. Mast cells were once thought to be basophils that migrated from the blood into their resident tissues, but they are now known to be different types of cells.
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 canal is cleaned via earwax, which naturally migrates to the auricle. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.
Demodex is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of Demodex are known. Two species live on humans: Demodex folliculorum and Demodex brevis, both frequently referred to as eyelash mites, alternatively face mites or skin mites.
In modern Western body piercing, a wide variety of materials are used. Some cannot be autoclaved, and others may induce allergic reactions, or harbour bacteria. Certain countries, such as those belonging to the EU, have legal regulations specifying which materials can be used in new piercings.
An epidermoid cyst or epidermal inclusion cyst is a benign cyst usually found on the skin. The cyst develops out of ectodermal tissue. Histologically, it is made of a thin layer of squamous epithelium.
Otoplasty is a procedure for correcting the deformities and defects of the auricle, whether these defects are congenital conditions or caused by trauma. Otoplastic surgeons may reshape, move, or augment the cartilaginous support framework of the auricle to correct these defects.
Stretching, in the context of body piercing, is the deliberate expansion of a healed piercing for the purpose of wearing certain types of jewelry. Ear piercings are the most commonly stretched piercings, with nasal septum piercings, tongue piercings and lip piercings/lip plates following close behind. While all piercings can be stretched to some degree, cartilage piercings are usually more difficult to stretch and more likely to form hypertrophic scars if stretched quickly. Dermal punching is generally the preferred method for accommodating larger jewelry in cartilage piercings.
Darwin's tubercle is a congenital ear condition which often presents as a thickening on the helix at the junction of the upper and middle thirds.
Tissue alpha-L-fucosidase is an enzyme that in humans is encoded by the FUCA1 gene.
The prostaglandin D2 receptor 1 (DP1), a G protein-coupled receptor encoded by the PTGDR1 gene (also termed PTGDR), is primarily a receptor for prostaglandin D2 (PGD2). The receptor is a member of the prostaglandin receptors belonging to the subfamily A14 of rhodopsin-like receptors. Activation of DP1 by PGD2 or other cognate receptor ligands is associated with a variety of physiological and pathological responses in animal models.
High affinity immunoglobulin epsilon receptor subunit beta is a protein that in humans is encoded by the MS4A2 gene.
Frank's sign is a diagonal crease in the ear lobe extending from the tragus across the lobule to the rear edge of the auricle. The sign is named after Sanders T. Frank.
Red ear syndrome (RES) is a rare disorder of unknown etiology which was originally described in 1994. The defining symptom of red ear syndrome is redness of one or both external ears, accompanied by a burning sensation. A variety of treatments have been tried with limited success.
Perichondritis is inflammation of the perichondrium, a layer of connective tissue which surrounds cartilage. A common form, auricular perichondritis involves infection of the pinna due to infection of traumatic or surgical wound or the spread of inflammation into depth. It may lead to severe deformation of the pinna if not treated vigorously with IV antibiotics. The causative organism is usually Pseudomonas aeruginosa. A rare form is laryngeal perichondritis. It develops suddenly due to an injury, virulent organisms or compromised immune status of the host, and also affects cartilage of the larynx. This may result in deformations and stenoses.
The Nickel Directive was a European Union directive regulating the use of nickel in jewellery and other products that come into contact with the skin. Since 1 June 2009, it has been subsumed into the REACH Regulation, specifically item 27 of Annex XVII to that regulation. Nevertheless, the term Nickel Directive is still used to refer to the restrictions on nickel usage and the prescribed test method for quantifying nickel release from products EN 1811.
Auricular hypertrichosis is a genetic condition expressed as long and strong hairs growing from the helix of the pinna.
Ear piercing is one of the oldest forms of body modification. It occurs when holes are created on the ear lobes or cartilage to allow the insertion of decorative ornaments, such as earrings. Ear piercing in children has been around for centuries as part of ritualistic and cultural traditions but has continued to become a worldwide mainstream fashion statement. It is extremely common in Nigeria, India, Brazil and Hispanic countries.
Metal allergies inflame the skin after it has been in contact with metal. They are a form of allergic contact dermatitis. They are becoming more common, as of 2021, except in areas with regulatory countermeasures.