Morphometric study of ear lobule in northwest Indian ... - Springer Link

Anatomical Science International (2007) 82, 98–104

doi: 10.1111/j.1447-073x.2007.00166.x

Original Article Blackwell Publishing Asia

Morphometric study of ear lobule in northwest Indian male subjects Anshu Sharma, Navjot Kaur Sidhu, Mahesh Kumar Sharma, Kanchan Kapoor and Balbir Singh Department of Anatomy, Government Medical College, Chandigarh, India

Abstract A total of 260 male subjects between 1 and 80 years of age of north-west region of India were studied with regard to morphometry of the ear lobule. The purpose of the present study was to obtain average values and range of measurements of several parameters of the ear lobule and the differences between right and left lobules. Female subjects were excluded from the study due to piercing. Various measurements of lobule were taken with the help of Vernier and Lange’s calipers. The results of the aforementioned measurements were analyzed statistically using Student’s t-test. The maximum length of the lobule increased appreciably between 6–15 years and 41– 80 years. The breadth of the ear lobule increased up to the age of 15 years and was almost static between the ages of 16 and 40 years and increased again from 41 years onwards. Length of the lobule showed significant growth from the age group of 6–10 to 11–15, 21–40 to 41–60 and 41–60 to 61– 80 years on the right side and 6 –10 to 11–15 and 21–40 to 41–60 years on the left side. Breadth and thickness of ear lobule also showed statistically significant growth pattern in some age groups. On comparing the ear lobe dimensions with the studies available in other populations of the world, it was observed that north-west Indians have smaller ear lobules as compared to Caucasian and Japanese populations. In the present study, the frequency of attached (square) type of lobules was the maximum, followed by free (pendulous) type and tapering lobules. These findings were similar to those found among the Onge tribe of Andhra (India) and Newars of Nepal. Key words: ear lobule, pendulous, root attachment, square, tapering.

Introduction The studies of the ear initially evolved from the development of surgical techniques for the treatment of congenital deformities and the reconstruction of traumatically injured ears (Tolleth, 1978; Avelar, 1986). Lobule parameters are important for plastic surgeons who aim to achieve a proper balance between right and left earlobes in reconstruction surgeries. These parameters also give information on age and sex and play a valuable role in forensic investigations. The ear lobule is the last part of the auricle to develop (Standring et al., 2005). Ear lobe elongation is associated with the natural aging process (McKinney et al., 1993). The lobule is absent or rudimentary in Anthropoides and best developed in civilized races. It is a new feature that apparently serves no useful function unless it is pierced for carrying ornaments, tobacco tins etc. (Hooton, 1965). Correspondence: Dr Anshu Sharma, 1151C, Sector 32B, Chandigarh 160030, India. Email: [email protected], [email protected] Received 29 May 2006; accepted 30 August 2006. © 2007 The Authors Journal compilation © 2007 Japanese Association of Anatomists

Metric analysis requires the choice of an appropriate standard because there is evidence that populations are metrically distinct (Frutos, 2002). Brucker et al. (2003) studied ear morphometry in 547 subjects ranging in age from 20 to 80 years. According to them significant age changes were observed only in the length of the lobule. However the width of the lobule decreased reciprocally. Another study (Nakamura, 1995) modified the preexisting Ishikawa method (Ishikawa et al., 1985). The author classified lobule into three types: tapering, square and pendulous. Ear lobule attachment was found to be an interesting marker in population genetics (Bhasin, 1969). In a study of the Newars of Nepal, frequency of attached lobule was 43.20% whereas 5.29% ears were found to be without lobule. Mohanraju and Mukhrejee (1973) recommended frequency of attached lobule for population studies and quantitative variation for genetic analysis. A study (Suzuki, 1950) based on 1130 families in Japan did not confirm that the free lobule is a dominant characteristic. Gates (1954) attempted to evaluate the mode of inheritance of this trait between black subjects with no lobule to Caucasian subjects possessing mostly free lobules. The author observed that the attached type is possibly

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an African character. According to Lai and Walash (1966), the frequency of attached ear lobule among Japanese subjects is 67.1% and in Chinese subjects it is 64.3%, which is quite high as compared to 35.1% in Indian subjects. Chattopadhyay (1968) reported the frequency of ear lobules as 4.67% among the jats of Delhi. Some authors (Mohanraju & Mukhrejee, 1973) have also studied frequency of ear lobe attachment in an Andhra village. A similar study was done by Pal (1970) among the Onge tribe, a small community living in the dense tropical forest of the little Andaman islands. Kenny (1989) suggested an interesting association between the diagonal ear lobe crease and myocardial infarction risk. The ear lobule crease points to an area on the pinna corresponding to heart in acupuncture map. Recent studies (Brady et al., 1987; Kenny & Gilligan, 1989) have also examined the correlation between diagonal ear lobule crease and the presence of coronary disease prospectively. Earology or otomorphology, which is used for identification through photograph or ear prints, has been used in forensic medicine and criminology (Feenstra, 2000). The present study is an effort to explore the anatomic changes in ear morphology with age for northwest Indian male subjects, and to compare the present observations with those available in the literature.

Table 1. Distribution of cases according to age of subject Serial no.

Group

1. 2. 3. 4. 5. 6. 7.

A B C D E F G

Age (years)

No. cases

1–5 6–10 11–15 16–20 21–40 41–60 61–80

50 50 50 50 20 20 20

Material and method A total of 520 ears in 260 male subjects aged 1–80 years were studied for ear lobule morphometry. Ear lobules of both sides were measured to study anatomic and morphometric features, using Vernier caliper. Men with a history of trauma, surgery, disease, malignancy of lobule, mental retardation and piercing were not included in the study. Female subjects were also not included in the study because of the custom of piercing of lobules in India for the wearing of ornaments, which leads to lengthening of lobule. The protocol for the research project was approved by the institutional ethics committee and the provisions of Declaration of Helsinki (1995) where adhered to. Each group except E, F and G had 50 subjects. In the E, F and G groups there were 20 subjects because of non-availability of sufficient numbers during the period of study. Subjects were divided into seven age groups (Table 1). The following parameters of the lobule were observed (Fig. 1): (i) presence/absence; (ii) shape: the ear lobule was classified into three types according to the grade of the angle (θ) between the base of the auricle and a line drawn and extended from starting point of the lower margin of lobule (Fig. 2): (a) tapering, θ = 30–69°, (b) square, θ = 70–109°, (c)

Figure 1. Systems of lines used in measurement of ear lobule.

pendulous, θ ≥ 110°; (iii) length (LL1): along a vertical line drawn from the intertragic incisure to the caudal tip of lobule; (iv) breadth (L2B): maximum breadth of ear lobule anteroposteriorly; (v) thickness (L3T): thickness of ear lobule at its midpoint; and (vi) root: (a) free (pendulous), intermediate (tapering), attached (square) and (b) extent of attachment, measured along the base of ear lobule from highest to the lowest point of attachment. All the results were tabulated and statistically analyzed using Student’s t-test to assess the significant changes in lobule with respect to age and side. The data were compared with the available data on other population groups.

© 2007 The Authors Journal compilation © 2007 Japanese Association of Anatomists

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0.81 ± 0.21 0.82 ± 0.20 0.93 ± 0.27 1.04 ± 0.28 1.15 ± 0.33 1.20 ± 0.33 1.87 ± 0.38 0.77 ± 0.24 0.80 ± 0.20 0.81 ± 0.30 1.02 ± 0.29 1.07 ± 0.30 1.10 ± 0.32 1.69 ± 0.42 0.25 ± 0.04 0.30 ± 0.04 0.29 ± 0.04 0.35 ± 0.08 0.30 ± 0.05 0.34 ± 0.04 0.36 ± 0.03 0.25 ± 0.04 0.30 ± 0.04 0.30 ± 0.03 0.34 ± 0.06 0.30 ± 0.05 0.34 ± 0.04 0.36 ± 0.03 1.82 ± 0.33 1.89 ± 0.26 2.27 ± 0.28 2.03 ± 0.23 2.14 ± 0.28 2.22 ± 0.53 2.56 ± 0.39 1.42 ± 0.22 1.47 ± 0.24 1.69 ± 0.33 1.73 ± 0.26 1.82 ± 0.25 2.25 ± 0.59 2.54 ± 0.42 1–5 6–10 11–15 16–20 21–40 41–60 61–80 A B C D E F G

No. cases

50 50 50 50 20 20 20

1.41 ± 0.24 1.42 ± 0.26 1.60 ± 0.26 1.67 ± 0.24 1.67 ± 0.25 2.01 ± 0.45 2.35 ± 0.58

1.80 ± 0.31 1.91 ± 0.26 2.19 ± 0.21 2.05 ± 0.24 2.13 ± 0.32 2.40 ± 0.52 2.62 ± 0.46

Left Right Right Left Right Left Right

Breadth (L1B) (Mean ± SE)

Age (years)

The length, breadth, thickness and extent of attachment of root were measured in male subjects ages between 1 and 80 years. These measurements in various age groups are shown in Table 2. The average length of right side increased from 1.41 ± 0.24 cm to 2.35 ± 0.58 cm and that of the left side from 1.42 ± 0.22 cm to 2.54 ± 0.42 cm. The average breadth of the ear lobule ranged between 1.80 ± 0.31 cm to 2.62 ± 0.46 cm on the right side and from 1.82 ± 0.33 cm to 2.56 ± 0.39 cm on the left side. The average thickness of ear lobule ranged between 0.25 ± 0.04 cm and 0.36 ± 0.03 cm. The average length of attachment of the root was between 0.77 ± 0.24 to 1.69 ± 0.42 cm on the right side and 0.81 ± 0.21 cm to 1.87 ± 0.38 cm on the left side. Growth trend in measurements of right and left lobules in different age groups is shown in Fig. 3. The length of ear lobule increased up to the age of 80 years. A sharp increase was seen between 6– 15 and 41–80 years of age.

Group

Measurements of the lobule

Length (L1L) (Mean ± SE)

Figure 2. Various shapes of ear lobule. (a) Tapering, θ = 30– 69°; (b) square, θ = 70–109°; (c) pendulous, θ ≥ 110°.

Table 2. Comparison of the mean measurements (cm) of lobule in different age groups

Thickness (L2T) (Mean ± SE)

Left

Root attachment (Mean ± SE)

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The breadth of the ear lobule increased up to the age of 15 years. A small decrease was seen in the present subjects between 16 and 40 years. Progressively higher values were again seen up to the age of 80 years.

A very small increase in the thickness of ear lobule was noted with increasing age. The length of attachment of the root, however, increased with the age. A sharp increase was seen between the age of 60 and 80 years. The length, breadth, thickness and attachment of root of the lobule were statistically insignificant in relation to the right and left side, with one exception. For the 11–15 years age group, length of the attachment of the root on the left side was found to be significantly larger than the right side. Various age groups were compared statistically for length, breadth, thickness and attachment of root (Table 3). The length of the lobule was significantly different from the groups B to C, E to F and F to G on the right side and B to C and E to F on the left side. Breadth of the lobule was statistically significantly different from the age groups B to C, C to D on the right side and B to C, C to D and F to G on the left side. Thickness of ear lobule was statistically significantly different in almost all the age groups for both sides. Measurement of attachment of root of the lobule was significantly different for the age groups C to D, F to G on the right side and B to C, D to E and F to G on the left side. This shows that the maximum changes in all the parameters occur between the age groups 6–11(B) and 11–15 (C) and then from group C to D. These changes were most noticeable between 6 and 15 years. Various shapes of ear lobule were noted. These were classified as tapering, square and pendulous (Fig. 4). Table 4 shows the percentage of occurrence of different shapes of lobule. In the present study shape of ear lobule was found to be bilaterally symmetrical in all cases. Out of 260 subjects 102 (39.2%) had pendulous ear lobule, 45 (17.3%) had tapering and 113 (43.5%) had square lobule bilaterally. The square type of ear lobule is the most common type in north-west Indian population.

Discussion Figure 3. Comparison of mean measurements of (a) right lobule and (b) left lobule in different age groups. () Length L1L; () breadth L2B; () thickness L3T; (×) root attachment.

The external ear is derived from tissue in the area of the contiguous edges of the first pharyngeal

Table 3. Comparison of changes in measurements of right and left lobule in different age groups Length L1L P Group

Age (years)

A–B B–C C–D D–E E–F F–G

1–5 to 6–10 6–10 to 11–15 11–15 to 16–20 16–20 to 21–40 21–40 to 41–60 41–60 to 61–80

Breadth L2B P

Thickness L3T P

Attachment of root P

Right

Left

Right

Left

Right

Left

Right

Left

0.84190 0.00080 0.16497 1.00000 0.00536 0.04520

0.28014 0.00024 0.50253 0.19060 0.00473 0.08126

0.05751 0.00000 0.00250 0.25746 0.05521 0.16463

0.24165 0.00000 0.00001 0.09427 0.55405 0.02635

0.00000 1.00000 0.00006 0.01041 0.00811 0.08159

0.00000 0.21428 0.00001 0.01164 0.00811 0.08159

0.49874 0.84502 0.00058 0.52110 0.76127 0.00001

0.80774 0.02270 0.04827 0.16310 0.63468 0.00000


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Figure 4. Ear lobule: (a) tapering; (b) square; (c) pendulous.

Table 4. Comparison of percentage of different shapes of lobule in different age groups

Group

Age (years)

No. cases

A B C D E F G Total

1–5 6–10 11–15 16–20 21–40 41–60 61–80 1–80

50 50 50 50 20 20 20 260

Pendulous Right 22 20 24 25 5 6

(44) (40) (48) (50) (25) (30) – 102 (39.2%)

Shape (n (%)) Tapering Left 22 20 24 25 5 6

(44) (40) (48) (50) (25) (30) –

pouch where the mandibular and hyoid arches join (Hunter & Yotsuyanagi, 2005). The auricle develops from six hillocks present around the hyomandibular groove. The lobule develops from hillock 6 and is the last part of the auricle to develop (Standring et al., 2005). An interesting account of various lobule anomalies and their associated syndrome is given by Hunter and Yotsuyanagi (2005). Although it has been suggested that anomalies of the insertion and orientation of intrinsic muscles of the pinna may be responsible for variation in external ear morphology (Smith & Takashima, 1978), it has been noted that in many cases the anomalous insertion might be secondary. In the case of lobule the insertion of extrinsic muscle is definitely not a factor affecting the shape because the lobule does not have any extrinsic muscle.

Right 11 14 8 3

(22) (28) (16) (6) – 1 (5) 8 (40) 45 (17.3%)

Left 11 14 8 3

(22) (28) (16) (6) – 1 (5) 8 (40)

Square Right 17 16 18 22 15 13 12 113

(34) (32 (36) (44) (75) (65) (60) (43.5%)

Left 17 16 18 22 15 13 12

(34) (32 (36) (44) (75) (65) (60)

The present study interprets the lobule morphometrically. The purpose of the present study was to establish lobule parameters in north-west Indian subjects with special reference to its bilateral symmetry. Study of ear lobule attachment and its mode of inheritance in man has attracted much attention during the last few decades. A large lobule is seen as a sign of aging. McKinney et al. (1993) have analyzed the form and shape of the ear lobule morphometrically, giving results that are useful, both from a functional as well as a clinical point of view. Various authors have adopted different methods for various parameters. A few authors (McKinney et al., 1993; Azaria et al., 2003; Brucker et al., 2003) measured lobule length and width while others (Bhasin, 1969; Pal, 1970) have mainly concentrated upon the attachment



of the lobule. According to these studies, the lobule is the most developed in European and Mongoloid subjects. Black subjects have a small, rounded ear with little or no lobule. Hooton (1965) has noted that the ear is relatively shorter and broader in infancy and during maturity than later in life. In middle aged and elderly persons this organ shows a recrudescence of growth and becomes much larger and more elongated, particularly the lobule. It is a well-established fact that morphological characters and dimensions vary in different races. Various authors have studied the dimensions of ear lobes in different populations. According to Azaria et al. (2003), sex and age are the main factors influencing ear lobe length; other factors including ethnicity, skin complexion and body mass index are apparently non-contributory. Some other authors (Vollmer, 1937; Adamson et al., 1965; Nakamura, 1995) too could not find any significant influence of ethnic origin on ear lobe length. Other authors, however (Dutta, 1963; Lai & Walash, 1966; Pal, 1970; Mohanraju & Mukhrejee, 1973) have described ear lobule attachment in various populations. There are considerable interpopulation variations. Lobule study appears to be an interesting marker in population genetics. Earlier studies (Rubin et al., 1962; Loeb, 1972) have determined the normal lobule length to be around 2 cm. In a study on Caucasian, African, Asian and Indian subjects, the average length of lobule was found to be 1.9 cm (range 1.3–2.5 cm) (McKinney et al., 1993). It was observed that north-west Indian subjects have smaller ear lobules (1.8 cm, range 1.41–2.41 cm) as compared to Caucasian and Japanese populations. Brucker et al. (2003) measured lobule length and width in subjects between 15 and 65 years of age. They reported that the length of the lobule increased from 1.78 cm to 1.99 cm while the width decreased from 2.10 cm to 1.91 cm. The authors stated that the lobular length is the only measurement that changes significantly with age. When the lobular length was subtracted from total ear length, however, statistical significance was lost. In the present study it was found that the length of the lobule increased with age on both sides (range 1.41–2.59 cm). Breadth also increased with age except in age group D, where there was a small decrease. The thickness and root attachment also increased with the age. No data on root attachment and thickness of lobule were available for comparison. Azaria et al. (2003) measured the ear lobule length from the intertragic incisure to the caudal tip and observed the anatomical shape at various ages. They found that earlobe length had a statistically significant difference in the age groups of 20–40 years, 40–60 years and >60 years. Mckinney et al.

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(1993) did not find a significant correlation between ear lobe height and aging. In another study (Brucker et al., 2003) lobular height increased significantly with age in both men and women. However, there was no significant difference in the lobular width. In the present study length of the lobule had significant growth from the age groups of B to C, D to E and F to G on the right side and B to C and D to E on the left side. Breadth of the lobule was also statistically significant for growth in the age groups of B to C (6–10 vs 11–15 years) and C to D on the right side and B to C, C to D and F to G on the left side. Thickness of the lobule had significant growth in all the age groups except B–C and F–G, while attachment of the root showed significant growth for the age groups B–C, C–D and F–G. According to Lai and Walash (1966), the frequency of attached ear lobule among Japanese subjects is 67.1% and in Chinese subjects it is 64.3%, which is quite high as compared to 35.1% in Indian subjects. Chattopadhyay (1968) reported frequency of attached ear lobules as 18.70% among the jats of Delhi. Pal (1970) found a frequency of 24.44% free ear lobules and 48.89% attached ear lobules in tribes of the Andaman islands. However, others (Dutta & Ganguly, 1965) found 63.92% free lobes in Brahmins and 25.49% attached ear lobules in the Muslims of Central India. Basu (1968) collected tribal data in Madhya Pradesh and found a different range (19.7–27.7%) among the tribal population. Bhasin (1969) observed attached ear lobes in 43.2% of the population in a study on Newar male subjects in Nepal. In the present study 102 subjects (39.2%) had pendulous, 45 (17.3%), tapering, and 113 (43.5%) square (attached) ear lobule. The square lobule was found to be the most common type of ear lobule in the north-west Indian population. The attachment of the lobule was compared with studies done in other parts of the Indian subcontinent. The frequency of attached or square type of lobules was similar to that in Nepal (Bhasin, 1969). In the present study, the frequencies of attached (square), intermediate (tapering) and free (pendulous) types of ear lobule were similar to those found in the Onge tribe of Andhra Pradesh (Pal, 1970). Pendulous and tapering types of lobule were more frequent in Brahmin, Chamar, Gandhabanik and Intermediate castes of Madhya Pradesh (India) while the frequency of the square type was lower (Basu, 1968). Another study showed that the frequency of the free type of lobules in the Assamese population was greater than the attached type, and the partly attached lobule was the least common (Das, 1967). In the present study the majority of the lobules were of the attached square type, and the free pendulous type was lower in frequency. Frequency of tapering lobules was the least.


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These findings are similar to those found among the Onge tribe of Andhra (India) (Mohanraju & Mukhrejee, 1973) and the Newars of Nepal (Bhasin, 1969).

Conclusion In the present study it was observed that all the measurements increased with the age. The maximum length of the lobule increased appreciably between 6–15 years and 41–80 years. The breadth of the ear lobule increased up to the age of 15 years and it was almost static between the age of 16 and 40 years, and increased again from 41 years onwards. Length of the lobule showed significant growth from age groups B to C, E to F and F to G on the right side and B to C and E to F on the left side. Breadth and thickness of ear lobule also showed statistically significant growth in some age groups. The lobule dimensions were compared with the studies available in other populations of the world. It was observed that north-west Indian subjects have smaller ear lobules as compared to Caucasian and Japanese populations. The attachment of the ear lobule also varied in different races. In the present study, the frequency of the attached (square) type of lobules was the maximum, followed by the free (pendulous) type and tapering lobules. These findings are similar to those found among the Onge tribe of Andhra (India) (Mohanraju & Mukhrejee, 1973) and Newars of Nepal (Bhasin, 1969). The present study shows that lobule attachment is a better parameter for studying the ethnic variation.

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