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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 5  |  Issue : 2  |  Page : 96-98

Symmetry and isometry of human adult hyoid bone: A cadaveric study in North Indian population


1 Department of Anatomy, Government Medical College, Patiala, Punjab, India
2 Department of Anatomy, Government Medical College, Amritsar, Punjab, India

Date of Web Publication9-Apr-2018

Correspondence Address:
Rajan Kumar Singla
Department of Anatomy, Government Medical College, Patiala, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/cjhr.cjhr_113_17

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  Abstract 


Introduction: Hyoid bone fracture is one of the most integral parts of internal examination during autopsy of hanging, ligature strangulation, or a throttling case. The reasons why some hyoids fracture and others do not may be related to the nature, magnitude, and position of the force applied to the neck, age of victim, nature of instrument (ligature or hand) used to strangle, and intrinsic anatomical features of the hyoid bone, such as rigidity and shape of the bone and symmetry of greater horns. Materials and Methods: The material for the present study comprised of 30 dried hyoid bones (M:F: 15:15). Their outline was drawn on the graph paper to study the symmetry and isometry of the bone. Results: Forty percent of the hyoids bones were symmetrical, while 60% were asymmetrical. Similarly, the number of anisometric bone is more (86.6%) as compared with isometric bone (13.3%) in both the sexes. Conclusion: Hyoid bone is not bilaterally symmetrical bone. The incidence of asymmetrical and anisometric bones is more as compared with symmetrical and isometric bones in both the sexes.

Keywords: Hyoid bone, isometry, symmetry


How to cite this article:
Kalyan B, Singla RK, Sharma RK. Symmetry and isometry of human adult hyoid bone: A cadaveric study in North Indian population. CHRISMED J Health Res 2018;5:96-8

How to cite this URL:
Kalyan B, Singla RK, Sharma RK. Symmetry and isometry of human adult hyoid bone: A cadaveric study in North Indian population. CHRISMED J Health Res [serial online] 2018 [cited 2018 Nov 19];5:96-8. Available from: http://www.cjhr.org/text.asp?2018/5/2/96/229581




  Introduction Top


The hyoid bone is a rather neglected structure of the human skeleton which has not been given sufficient attention.[1] Anatomically, the bone consists of five elements, an unpaired body, and pairs of greater and lesser horns. All elements originate in the cartilaginous tissue of the pharyngeal (also known as branchial) arches. By a generally accepted concept of origin, the lesser horns and superior part of the body above the horizontal ridge are derived from the second, so-called hyoid arch, while the rest of the body and greater horns differentiate from the third pharyngeal arch.[2]

Observation of hyoid bone fracture is one of the most integral parts of internal examination during autopsy of hanging, ligature strangulation, or a throttling case. Its incidence ranges from 0% to 68% in hanging and is said to be increased with age after 40 years.[3] The reasons why some hyoids fracture and others do not may be related to the nature, magnitude, and position of the force applied to the neck, age of victim, nature of instrument (ligature or hand) used to strangle, and intrinsic anatomical features of the hyoid bone, such as rigidity and shape of the bone and symmetry of greater horns.[4]

The left-right symmetry of hyoid bones corresponds to object symmetry, where a single structure is identical according to a given or selected plane, such as mid-sagittal plane. The matching symmetry, in contrast, is referred to in situ ations where two separate objects exist as mirror images of each other.[5] Like most human skeletal structures, the hyoid bone is generally assumed to be bilaterally symmetrical. The evidence of asymmetry in the human hyoid bone has been explored in relation to the individual's sex [6] and body size.[7]

On the other hand, the concept of isometry/anisometry deals with the position of tip of greater cornua with respect to each other. If the tips of greater cornua lie in the same coronal plane, the hyoid bone said to be isometric if not so, it is anisometric.[8]

In the present study, an attempt has been made to find out the incidence of symmetrical/asymmetrical hyoid bones and isometric/anisometric hyoid bones and to correlate the same with its clinical and forensic importance.


  Materials and Methods Top


The material for the present study comprised 30 dried hyoid bones (M:F: 15:15), made available from Department of Anatomy, Government Medical College, Amritsar. Bones were labeled from 1 to 30 with suffix M(male) or F(female). Each hyoid bone was examined for symmetry/asymmetry and isometry/anisometry.

Symmetry

For determining the symmetry of the hyoid bone, the outline of the bone was drawn on graph paper by pencil. The distal ends of the two greater cornua were joined (CD in [Figure 1]). Major transverse axis was also drawn (AB in [Figure 1]). A line was drawn in the mid-sagittal axis of the bone from the posterior surface of the body intersecting the previous lines at pointsPand P'. If the distance AP = PB, then the bone was labeled as symmetrical bone and if not, it was labeled as asymmetrical.
Figure 1: Symmetry of bone

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Isometry

A bone is isometric if the tips of both greater cornua fall in the same coronal plane. If it is not so, the hyoid bone is anisometric. For this, the bone was kept on graph paper with body lying parallel to x-axis, and then a line was drawn touching the tips of the two greater cornua. If it is parallel to x-axis it is isometric, otherwise anisometric. Here, it is worth mentioning that the length of two greater cornua may not be necessarily same in isometric bones (see [Figure 2]).
Figure 2: Symmetry and isometry of hyoid bones. (a) Symmetrical but anisometeric hyoid bone. (b) asymmetrical but isometric bone

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  Results Top


Symmetry

In the present study, out of 30 bones, 12 bones were symmetrical and 18 were asymmetrical. A number of asymmetrical bones were more than that of symmetrical bones in both the sexes [Table 1].
Table 1: Symmetry of hyoid bone

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Isometry

In the present study, only 4 bones (13.3%) (2 each in males and females) were isometric rest and 26 bones (86.6%) (13 each in males and females) were anisometric [Table 2].
Table 2: Isometry of hyoid bone

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  Discussion Top


Symmetry

[Table 1] compares the incidence symmetry of hyoid bone with the earlier study by Leksan et al.[9] As evident from the table the number of symmetrical bones were more as compared to asymmetrical bones in their study, while in the present study, number of asymmetrical bones were more than that of symmetrical bones. This difference may be attributed to the racial factors. Furthermore, Leksan et al.[9] found the incidence of symmetrical bones to be more in males and asymmetrical to be more in females, while in the present study, no such difference could be seen.

Forensic implication

Pollanen et al. found that unilateral fractures of hyoid bone are more common as compared with bilateral ones. This led them to believe that asymmetry of hyoid bone is responsible for determining the location of fractures.[10] It was further supported by the experimental hyoid distortion studies using interferometry which showed asymmetrical displacement of hyoids under applied loads.[11]

Isometry

Earlier, Papadopoulos et al. found anisometric bones in 59% of their sample. It was though more in our study, but definitely, the incidence of anisometric bones is more as compared with isometric ones.


  Summary Top


To summarize:

  1. The incidence of asymmetrical hyoid bones is more as compared with symmetrical bones
  2. The incidence of anisomery is more as compared with isometry in the hyoid bones
  3. Symmetry/asymmetry and isometry/anisometry of hyoid bones do not depict any sex difference.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Urbanova P, Hejna P, Zatopkova L, Safr M. The asymmetry and modularity of the hyoid bone. Int J Morphol 2014;32:251-60.  Back to cited text no. 1
    
2.
Scheuer L, Black S. Developmental juvenile osteology. London: Elsevier Ltd.; 2000.  Back to cited text no. 2
    
3.
Naik SK, Patil DY. Fracture of hyoid bone in cases of asphyxia deaths resulting from constricting force round the neck. J Indian Acad Forensic Med 2005;27:971-3.  Back to cited text no. 3
    
4.
Pollanen MS, Chiasson DA. Fracture of the hyoid bone in strangulation: Comparison of fractured and unfractured hyoids from victims of strangulation. J Forensic Sci 1996;41:110-3.  Back to cited text no. 4
    
5.
Klingenberg CP, Barluenga M, Meyer A. Shape analysis of symmetric structures: Quantifying variation among individuals and asymmetry. Evolution 2002;56:1909-20.  Back to cited text no. 5
    
6.
Pollanen MS, Ubelaker DH. Forensic significance of the polymorphism of hyoid bone shape. J Forensic Sci 1997;42:890-2.  Back to cited text no. 6
    
7.
Urbanová P, Hejna P, Zátopková L, Šafr M. The morphology of human hyoid bone in relation to sex, age and body proportions. Homo 2013;64:190-204.  Back to cited text no. 7
    
8.
Papadopoulos N, Lykaki-Anastopoulou G, Alvanidou E. The shape and size of the human hyoid bone and a proposal for an alternative classification. J Anat 1989;163:249-60.  Back to cited text no. 8
    
9.
Leksan I, Marcikić M, Nikolić V, Radić R, Selthofer R. Morphological classification and sexual dimorphism of hyoid bone: New approach. Coll Antropol 2005;29:237-42.  Back to cited text no. 9
    
10.
Pollanen MS, Bulger B, Chiasson DA. The location of hyoid fractures in strangulation revealed by xeroradiography. J Forensic Sci 1995;40:303-5.  Back to cited text no. 10
    
11.
Kasprzak H, Podbielska H, von Bally G, Fechner G. Biomechanical investigation of the hyoid bone using speckle interferometry. Int J Legal Med 1993;106:132-4.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2]



 

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Abstract
Introduction
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